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  • 1.
    Alipour, Nazanin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Yu, Shun
    Roth, Stephan
    Brüning, Karsten
    Vieyres, Arnaud
    Schneider, Konrad
    Structure and properties of polyethylene-based and EVOH-based multilayered films with layer thicknesses of 150 nm and greater2015Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 64, s. 36-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the structure and properties of two multilayered systems where polymers in adjacent layers were either miscible or immiscible. The miscible system consisted of 2, 17, 18, 24 and nominally 288 layers of alternating low-density (LDPE) and low-density/linear-low density (mPE) polyethylene layers with observed thicknesses ranging from 150 nm to 20 urn. The immiscible system consisted of 5 and 19 layer films with a combination of poly(ethylene-co-vinyl alcohol) (EVOH) (thickness: 9 and 1 gm, respectively), LDPE (17 and 7 gm) and a polyethylene adhesive (3 and 1 gm). The purpose of the multi-layering was to increase the crack growth resistance and, in the EVOH-based system, to decrease the oxygen transmission rate. Indeed, the crack growth resistance, as measured on tensile-tested notched films, increased with increasing number of layers. The thinnest polyethylene and polyethylene adhesive layers showed a clear ductile failure when fractured even in liquid nitrogen. Simultaneous synchrotron wide-angle/small-angle X-ray scattering and tensile testing indicated no new deformation features with changes in the layer thickness. The oxygen permeability was the same in the 5- and 19-layer EVOH-based films, but the uptake of n-hexane was strongly reduced in the 19-layer films, demonstrating the effective protective role of the EVOH layers. The n-hexane desorption data of the 2-layer LDPE/mPE film was successfully modeled using the diffusivities and solubilities of the single layers. Crystallization was slower and more confined in the films with thinner layers. The interlayer mixing in the melt (measured by isothermal crystallization from melts of initially layered polyethylene-based systems) was, as expected, significantly faster in the 24- and 288-multilayer films than in the 2-layer film.

  • 2. Badia, J. D.
    et al.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Ribes-Greus, A.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Assessing the MALDI-TOF MS sample preparation procedure to analyze the influence of thermo-oxidative ageing and thermo-mechanical degradation on poly (Lactide)2011Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 47, nr 7, s. 1416-1428Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PLA under mechanical recycling. Likewise, an accelerated thermal ageing over PLA glass transition was performed in order to simulate its service life. MALDI-TOF MS was used for the analysis and the sample preparation procedure was assessed by means of a statistical Design of Experiments (DoE). The quality effects in use for the analysis were signal-to-noise ratio and Resolution. Different matrixes, analyte/matrix proportions and the use of NaTFA as cationization agent were considered. A deep inspection of the statistical results provided a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measurement of PLA stated that the best combination of factors (levels) was the following: matrix (s-DHB), proportion analyte/matrix (1/5 V/V), and no use of cationization agent. Degradation primarily affected the initially predominant cyclic [LA(C)](n) and linear H-[LA(L)](n)-OH species, where LA stands for a PLA repeating unit. Intramolecular and intermolecular transesterifications as well as hydrolytic and homolytic reactions took place during the formation and disappearance of oligomeric species. In both degradation mechanisms induced by thermal ageing and thermo-mechanical degradation, the formation of H-[LA(L)](n)-O-CH(3) by intermolecular transesterifications was highlighted.

  • 3. Bedo, Daniel
    et al.
    Imre, Balazs
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap. Hungarian Academy of Sciences, Hungary; Budapest University of Technology and Economics, Hungary.
    Domjan, Attila
    Schoen, Peter
    Vancso, G. Julius
    Pukanszky, Bela
    Coupling of poly(lactic acid) with a polyurethane elastomer by reactive processing2017Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 97, s. 409-417Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A segmented polyurethane elastomer (PU) was synthesized in poly(lactic acid) (PLA) melt by reactive processing. The isocyanate component was anticipated to react with the end-groups of PLA resulting in the formation of block-copolymers. The stoichiometry of the functional groups was optimized in the preliminary experiments. Two different processing methods were compared in the further experiments: conventional mixing of PU with PLA (PLA/PU), and reactive blending (PLA-b-PU). The comparison of the structure and properties of compatibilized reactive blends and conventional physical blends clearly shows the benefits of reactive processing. Coupling resulted in a finer dispersion of the particles in the matrix leading to better mechanical properties in the reactive blend. The successful synthesis of PEA-b-PU block copolymers was confirmed by NMR spectroscopy. The isocyanate component was found to react only with the hydroxyl end-groups of PLA, while the formation of amide and acylurea groups was not detected on the carboxyl end.

  • 4.
    Bergenstråhle, Malin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Mazeau, Karim
    CNRS, Ctr Rech Macromol Vegetales.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Molecular modeling of interfaces between cellulose crystals and surrounding molecules: Effects of caprolactone surface grafting2008Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 44, nr 11, s. 3662-3669Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A technical problem in cellulosic nanocomposite materials is the weak interaction between hydrophilic cellulose and hydrophobic polymer matrices. One approach to solve this difficulty is to chemically graft monomers of the matrix polymer onto the cellulose surface. An important question is to understand the effect such surface modification has on the interfacial properties. Semi-empirical approaches to estimate work of adhesion based on surface energies do not provide information on specific molecular interactions. Details about these interactions were obtained using molecular dynamics (MD) simulation. Cellulose interfaces with water and caprolactone medium were modeled with different amounts of grafted caprolactone. The modification lead to an increased work of adhesion between the surface and its surrounding medium. Furthermore, the MD simulations showed that the interaction between cellulose, both modified and non-modified, and surrounding medium is dominated by Coulomb interactions, predominantly as hydrogen bonds.

  • 5.
    Carlmark, Anna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Larsson, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Grafting of cellulose by ring-opening polymerisation - A review2012Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 48, nr 10, s. 1646-1659Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    In this review, homogeneous and heterogeneous grafting from cellulose and cellulose derivatives by ring-opening polymerisation (ROP) are reported. Cellulose is biorenewable and biodegradable as well as a stiff material with a relatively low specific weight, foreseen to be an excellent replacement for synthetic materials. By utilising ROP of monomers such as -caprolactone or l-lactide from cellulose, composite materials with new and/or improved properties can be obtained. Grafting of solid cellulose substrates, such as cotton, microfibrillated cellulose (MFC) or cellulose nanocrystals, renders cellulose that can easily be dispersed into polymer matrices and may be used as reinforcing elements to improve mechanical and/or barrier properties of biocomposites. A surface grafted polymer can also tailor the interfacial properties between a matrix and the fibrillar structure of cellulose. When derivatives of cellulose are grafted with polymers in homogenous media, amphiphilic materials with interesting properties can be achieved, anticipated to be utilised for applications such as encapsulation and release.

  • 6.
    Chen, Fei
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Monnier, Xavier
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Gällstedt, Mikael
    Innventia, Sweden.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Wheat gluten/chitosan blends: A new biobased material2014Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 60, s. 186-197Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wheat gluten and chitosan are renewable materials that suffer from some poor properties that limit their use as a potential replacement of petroleum-based polymers. However, polymer blends based on wheat gluten and chitosan surprisingly reduced these shortcomings. Films were cast from acidic aqueous or water/ethanol solutions of wheat gluten and chitosan. Wheat gluten was the discontinuous phase in the 30-70 wt.% wheat gluten interval investigated. The most homogeneous films were obtained when reducing agents were used (alone or together with urea or glycerol). They consisted mainly of 1-2 mu m wheat gluten particles uniformly distributed in the continuous chitosan phase. Slightly smaller particles were also observed in the water/ethanol solvent system, but together with significantly larger particles (as large as 200 mu m). Both small and large particles were observed, albeit in different sizes and contents, when surfactants (both with and without a reducing agent) or urea (without a reducing agent) were used. The particles were often elongated, and preferably along the film, the most extreme case being observed when the glyoxal crosslinker was used together with sodium sulfite (reducing agent), showing particles with an average thickness of 0.6 mu m and an aspect ratio of 4.2. This film showed the highest transparency of all the blend films studied. For one of the most promising systems (with sodium sulfite), having good film homogeneity and small particles, the mechanical and moisture solubility/diffusivity properties were studied as a function of chitosan content. The extensibility, toughness and moisture solubility increased with increasing chitosan content, and the moisture diffusivity was highest for the pristine chitosan material. It is noteworthy that the addition of 30 wt.% wheat gluten to chitosan reduced the moisture uptake, while the extensibility/toughness remained unchanged.

  • 7.
    Claudino, Mauro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Johansson, Mats K. G.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Thiol-ene coupling of 1,2-disubstituted alkene monomers: The kinetic effect of cis/trans-isomer structures2010Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 46, nr 12, s. 2321-2332Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The free-radical induced reaction between a tri-functional thiol (2-ethyl-(hydroxymethyl)-1,3-propanediol trimercapto propionate) and two 1,2-disubstituted alkenes (methyl oleate and methyl elaidate) has been investigated under photochemical conditions. The photoreaction was monitored via time-resolved FUR, Raman and NMR spectroscopy to provide insights about the kinetics and efficiency in end-product formation. The information collected was subjected to numerical modelling using the GEPASI software using pre-established literature values for the rate coefficients in order to verify the proposed reaction scheme. The results confirm the thiol-ene reaction mechanism showing a very fast cis/trans-isomerization (<1.0 min) when compared with the total disappearance of unsaturations, indicating that the rate-limiting step controlling the reaction is the hydrogen transfer from the thiol involved in the formation of product. High thiol-ene conversions can be obtained at reasonable rates without major influence of side-reactions when performed in bulk indicating that this reaction is suitable for network forming purposes with mono-unsaturated fatty acid methyl esters derivatives. The kinetic and mechanistic information collected provides a basis for the design of new thiol-ene systems aiming at material and coating applications.

  • 8.
    Edlund, Ulrica
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Svensson, Marie
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Microsphere valorization of forestry derived hydrolysates2012Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 48, nr 2, s. 372-383Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A value-adding approach to the material utilization of non-cellulosic polysaccharides (NCPs) released from the lignocellulosic feedstock was realized via the formulation of renewable microspheres from wood hydrolysates using a purposely elaborated all edible water-in-oil emulsion technique. Four compositionally different hemicellulose rich wood hydrolysates were recovered from process waters in pulping and other hydrothermal treatments of hardwood and softwood. Multivariate screening designs were employed allowing for the identification and quantitation of significant process parameters and interaction effects governing the conversion of hydrolysates into small, smooth and well-defined microspheres with narrow size dispersity.

  • 9. Gil-Castell, O.
    et al.
    Badia, J. D.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Skövde University, Sweden.
    Ribes-Greus, A.
    Effect of the dissolution time into an acid hydrolytic solvent to taylor electrospun nanofibrous polycaprolactone scaffolds2017Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 87, s. 174-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hydrolysis of the polycaprolactone (PCL) as a function of the dissolution time in a formic/acetic acid mixture was considered as a method for tailoring the morphology of nanofibrous PCL scaffolds. Hence, the aim of this research was to establish a correlation between the dissolution time of the polymer in the acid solvent with the physico-chemical properties of the electrospun nanofibrous scaffolds and their further service life behaviour. The physico-chemical properties of the scaffolds were assessed in terms of fibre morphology, molar mass and thermal behaviour. A reduction of the molar mass and the lamellar thickness as well as an increase of the crystallinity degree were observed as a function of dissolution time. Bead-free fibres were found after 24 and 48 h of dissolution time, with similar diameter distributions. The decrease of the fibre diameter distributions along with the apparition of beads was especially significant for scaffolds prepared after 72 h and 120 h of dissolution time in the acid mixture. The service life of the obtained devices was evaluated by means of in vitro validation under abiotic physiological conditions. All the scaffolds maintained the nanofibrous structure after 100 days of immersion in water and PBS. The molar mass was barely affected and the crystallinity degree and the lamellar thickness increased along immersion, preventing scaffolds from degradation. Scaffolds prepared after 24 h and 48 h kept their fibre diameters, whereas those prepared after 72 h and 120 h showed a significant reduction. This PCL tailoring procedure to obtain scaffolds that maintain the nanoscaled structure after such long in vitro evaluation will bring new opportunities in the design of long-term biomedical patches.

  • 10. Gorochovceva, N.
    et al.
    Naderi, A.
    Dedinaite, Andra
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Makuska, R.
    Chitosan-N-poly(ethylene glycol) brush copolymers: Synthesis and adsorption on silica surface2005Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 41, nr 11, s. 2653-2662Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chitosan-N-poly(ethylene glycol) brush copolymers with different degree of substitution (DS) were synthesized via reductive amination of chitosan by rnethoxy poly(ethylene glycol) (MPEG) aldehyde. Chitosan-N-MPEG copolymers were high-molecular-weight products with desirable DS; solubility and solution viscosity of those copolymers depended on the method of the synthesis of MPEG aldehyde and on DS. Synthesis of MPEG aldehyde by the use of TEMPO radical/BAIB was not suitable because of partial oxidation of methoxy groups of MPEG resulting in bifunctional PEG derivatives leading to cross-linking. Adsorption studies of chitosan-N-MPEG graft copolymers oil silica surface show that these polymers adsorb in highly hydrated layers.

  • 11.
    Hatton, Fiona L.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Tailor-made copolymers for the adsorption to cellulosic surfaces2015Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 65, nr SI, s. 325-339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The utilization and modification of cellulose, in particular nanocelluloses, for applications in bioplastics and biocomposites has been well studied in recent years. There is an increasing need for materials with good mechanical properties from renewable resources to replace current polymeric materials derived from fossil fuels. The modification of cellulose is essential to improve compatibility with hydrophobic matrices. For this purpose, various modification techniques have been employed such as physical adsorption of polymers to cellulosic substrates. This review aims to summarize the existing literature describing the physical adsorption of tailor-made copolymers to cellulosic surfaces. This area of cellulose modification incorporates a broad range of polymeric materials, and the expansion of this method of cellulose modification is promising for future sustainable, renewable and 'green' material development.

  • 12.
    Henriksson, Marielle
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Henriksson, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Lindström, Tom
    STFI-Packforsk AB.
    An environmentally friendly method for enzyme-assisted preparation of microfibrillated cellulose (MFC) nanofibers2007Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 43, nr 8, s. 3434-3441Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microfibrillated cellulose nanofibers (MFC) provide strong reinforcement in polymer nanocomposites. In the present study, cellulosic wood fiber pulps are treated by endoglucanases or acid hydrolysis in combination with mechanical shearing in order to disintegrate MFC from the wood fiber cell wall. After successful disintegration, the MFC nanofibers were studied by atomic force microscopy (AFM). Enzyme-treatment was found to facilitate disintegration, and the MFC nanofibers produced also showed higher average molar mass and larger aspect ratio than nanofibers resulting from acidic pretreatment.

  • 13.
    Jonsson, Magnus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Nyström, Daniel
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Nordin, Ove
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Surface modification of thermally expandable microspheres by grafting poly(glycidyl methacrylate) using ARGET ATRP2009Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 45, nr 8, s. 2374-2382Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study demonstrates the surface modification of thermally expandable core/shell microspheres by grafting glycidyl methacrylate (GMA) using activators regenerated by electron transfer (ARGET) ATRP. To retain the expansion properties it was essential to minimize the shear forces, use solvents compatible with the microspheres and keep the reaction times short (three hours or less). Using microspheres with hydroxyl groups on the surface, it was found that after converting these to α-bromo esters, GMA could be grafted by ARGET ATRP using only 50 ppm of copper catalyst in toluene at 30 °C. Decent control of the polymerization was achieved with PMDETA as ligand reaching PDIs of 1.4 for the solution polymerization of GMA. When microspheres were present, the polymerization was less controlled with higher PDIs. The epoxide groups of the grafted microspheres were hydrolyzed by HCl in THF providing a hydrophilic surface of the microsphere. The expansion property of the microspheres was studied after each reaction step by thermal mechanical analysis, and it was found that the expansion capacity was well preserved with only limited negative effect on the microspheres.

  • 14.
    Khosravi, Sara
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik. Casco Adhes AB, AkzoNobel, SE-10061 Stockholm, Sweden.
    Nordqvist, P.
    Khabbaz, F.
    Ohman, C.
    Bjurhager, I.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Wetting and film formation of wheat gluten dispersions applied to wood substrates as particle board adhesives2015Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, s. 476-482Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The wetting, penetration, and film formation of wheat gluten dispersions on porous wood substrates have been studied using different microscopy techniques. The effect variation of wheat gluten concentration, processing temperatures, dispersion composition, and the application scheme has been studied. The results have been correlated to previously obtained results on the function of wheat gluten dispersions as adhesive binders for particle boards. The results show that the dispersions readily penetrate the porous wood substrate and that the key parameters for a successful gluing are the dispersion viscosity, concentration, and the application scheme.

  • 15. Krivorotova, T.
    et al.
    Makuska, R.
    Naderi, Ali
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Dédinaité, Andra
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Synthesis and interfacial properties of novel cationic polyelectrolytes with brush-on-brush structure of poly(ethylene oxide) side chains2010Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 46, nr 2, s. 171-180Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel cationic polyelectrolytes with a brush-on-brush structure of poly(ethylene oxide) (PEO) side chains and a charge-containing polyacrylate backbone were synthesized. The PEO side chains were not directly attached to the backbone but via polymethacrylate spacers, thus locating the PEO chains a distance away from the charged units of the backbone. The cationic brush-on-brush polyelectrolytes with high density of PEO chains showed a strong affinity to silica surfaces, provided the backbone charge density was high enough. The adsorption of these polymers was studied by QCM-D giving very high sensed mass, 20 mg/m(2). It was shown by direct force measurements that protective surface layers were formed by the novel polyelectrolytes, generating strongly repulsive steric forces, which provided an effective barrier against flocculation. The adsorbed layer was sufficiently robust to withstand sliding experiments under a pressure of up to 35 MPa. The friction force in water was very low. and the lubrication was characterized by a friction coefficient in the range of 0.02-0.06.

  • 16.
    Larsson, Emma
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Cobo Sanchez, Carmen
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Porsch, Christian
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Karabulut, Erdem
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Thermo-responsive nanofibrillated cellulose by polyelectrolyte adsorption2013Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 49, nr 9, s. 2689-2696Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, thermo-responsive nanofibrillated cellulose (NFC) has been produced by the adsorption of thermo-responsive polyelectrolytes to the NFC. Three block copolymers were synthesized in which the polyelectrolyte block was composed of quaternized poly(2-(dimethylamino)ethyl methacrylate) (qPDMAEMA) and the thermo-responsive block was composed of poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA). The block copolymers were synthesized employing atom transfer radical polymerization (ATRP) and the PDMAEMA block was utilized as a macroinitiator for the polymerizations of PDEGMA. The length and charge of the PDMAEMA block were kept constant in all three block copolymers, while three different molecular weights of the PDEGMA block was synthesized. The PDMAEMA block was quaternized to introduce positive charges and the block copolymers were subsequently adsorbed onto the negatively charged NFC that was dispersed in water. The lower critical solution temperatures (LCSTs) of the free block copolymers in solution were analyzed by dynamic light scattering (DLS). The composites were analyzed by QCM-D, FT-IR and TGA, which clearly showed an adsorption of the block copolymer onto the NFC. The grafted NFC showed a thermo-responsive behavior in solution upon heating and cooling, thus supporting that the properties of the polyelectrolyte can be transferred to the cellulose. By this methodology, thermo-responsive NFC materials can be produced in a straight-forward manner in water dispersions, without performing any chemical reactions on the NFC.

  • 17. Li, Chunliang
    et al.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Sablong, Rafael J.
    Koning, Cor E.
    High performance thiol-ene thermosets based on fully bio-based poly(limonene carbonate)s2017Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 96, s. 337-349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High glass transition temperature (Tg) thiol-ene networks (TENs) based on poly(limonene carbonate)s (PLCs), derived from orange oils and of potential degradability are described here. PLCs with moderate molecular weight were prepared by copolymerization of limonene oxide with CO2 and subsequent breakdown reactions. These PLCs were cured with multifunctional thiol monomers in the presence of thermal initiators via thiol-ene chemistry to generate poly(thioether-cocarbonate) networks. The thermal curing experiments were optimized by a kinetic study using real-time ATR-FTIR, in which a delayed gelation was observed. For the first time, an interesting "cage" effect was observed during the network formation initiated by DCP, in which the addition reactions of pendant isopropenyls on high molecular weight PLC chains were significantly enhanced by thiol-ene crosslinking at 160 degrees C. The resulting homogeneous TENs with high T(g)s (> 100 degrees C) and a wide range of thermomechanical properties, including rubbery moduli from 2.9 to 28.2 MPa, were obtained. The TENs also showed promising properties such as high transparency, good acetone resistance and high hardness, suggesting their potential application in coatings.

  • 18.
    Liu, Andong
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Berglund, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Fire-retardant and ductile clay nanopaper biocomposites based on montmorrilonite in matrix of cellulose nanofibers and carboxymethyl cellulose2013Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 49, nr 4, s. 940-949Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nacre-mimetic clay bionanocomposites of high clay content show interesting properties although low strain to failure is a limitation. For this reason, three-component nanocomposite films were prepared based on sodium montmorrilonite clay (MTM), a water-soluble cellulose derivative (CMC) of fairly high molar mass, in combination with nanofibrillated cellulose (NFC) from wood pulp. The nanocomposite is cast from an aqueous colloidal dispersion. First, the effects of CMC content on CMC/MTM compositions with high volume fraction of MTM (36-83 vol.%) were studied by FE-SEM, XRD, UV, DMTA and TGA. In addition, fire retardance and oxygen permeability characteristics were measured. The effect of NFC nanofiber addition to the matrix phase was then evaluated. This two-phase CMC/NFC matrix phase results in significantly improved modulus, strength but also strain to failure. NFC has a favorable effect by shifting catastrophic failure mechanisms to higher strains.

  • 19.
    Liu, Dongming
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pallon, Love K. H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Zhang, P.
    Diaz, A.
    Holler, M.
    Schneider, K.
    Olsson, Richard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Yu, Shun
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf W
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Cavitation in strained polyethylene/aluminium oxide nanocomposites2017Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 87, s. 255-265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The incorporation of metal oxide (e.g. Al2O3) nanoparticles has a pronounced positive effect on low-density polyethylene (LDPE) as an insulating material for high-voltage direct-current (HVDC) cables, the electrical conductivity being decreased by one to two orders of magnitude and charge species being trapped by the nanoparticles. The risk of debonding between the nanoparticles and the polymer matrix leading to electrical treeing via electrical discharges in the formed cavities was the motivation for this study. Scanning electron microscope (SEM), small-angle X-ray scattering (SAXS) and X-ray ptychographic tomography were used to study a series of LDPE nanocomposites which contained Al2O3 nanoparticles treated with silanes having terminal alkyl groups of different lengths (methyl, octyl and octadecyl). When specimens were subjected to a tensile strain (a typical specimen stretched beyond the onset of necking consisted of three zones according to SEM of specimens that were studied after removal of the external force: an essentially cavitation-free zone with low local plastic strain, a transitional zone in which local plastic strain showed a marked increase and the revealed concentration of permanent cavities increased with increasing plastic strain and a highly strained zone with extensive cavitation), the cavitation occurred mainly at the polymer-nanoparticle interface according to SEM and X-ray ptychographic tomography and according to SEM progressed with increasing plastic strain through an initial phase with no detectable formation of permanent cavities to a period of very fast cavitation and finally almost an order of magnitude slower cavitation. The polymer/nanoparticle interface was fractal before deformation, as revealed by the profile of the Porod region in SAXS, presumably due to the existence of bound polymers at the nanoparticle surface. A pronounced decrease in the interface fractal dimension was observed when the strain exceeded a critical value; a phenomenon attributed to the stress-induced de-bonding of nanoparticles. The strain-dependence of the interface fractal dimension value at low strain levels between composites containing differently treated nanoparticles seems to be an indicator of the strength of the nanoparticle-polymer interface.

  • 20.
    Liu, Dongming
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pallon, Love
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Zhang, Peng
    Deutsches Elektronen-Synchrotron (DESY).
    Diaz, Ana
    Paul Scherrer Institut.
    Holler, Mirko
    Paul Scherrer Institut.
    Schneider, Konrad
    Leibniz Institut für Polymerforschung Dresden.
    Olsson, Richard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Yu, Shun
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Cavitation in strained polyethylene/aluminium oxide nanocomposites2016Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945Artikkel i tidsskrift (Fagfellevurdert)
  • 21.
    Liu, Dongming
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Pourrahimi, Amir Masoud
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Influence of nanoparticle surface treatment on particle dispersion and interfacial adhesion in low-density polyethylene/aluminium oxide nanocomposites2015Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 66, s. 67-77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of silsesquioxane coating of aluminium oxide nanoparticles on their dispersion and on the interfacial strength between nanoparticles and polymer matrix in low-density polyethylene composites was studied. The surface chemistry of the nanoparticles was tailored from hydroxyl groups to alkyl groups with different lengths by reacting methyltrimethoxysilane (C1), octyltriethoxysilane (C8) or octadecyltrimethoxysilane (C18) with aluminium oxide nanoparticles. The core–shell structure of the coated nanoparticles was assessed by transmission electron microscopy, infrared spectroscopy and thermogravimetry. The inter-particle distance of the nanocomposite based on C8-coated nanoparticles showed only a small deviation from the ideal value, indicating a very good particle dispersion in the polymer. The interfacial adhesion between nanoparticles and matrix was determined by stretching nanocomposite specimens in a tensile testing machine to strains well beyond the yield point. A drop in the stress–strain curve indicated the onset of cavitation and necking in the nanocomposites. Samples stretched to different strain levels were studied by scanning electron microscopy and the cavitation was found to be confined to particle interfaces. The composite based on C18-coated nanoparticles showed the highest strain at cavitation/necking suggesting a high interfacial adhesion between nanoparticles and polymer.

  • 22.
    Lönnberg, Hanna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Fogelström, Linda
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Berglund, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Hult, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Surface grafting of microfibrillated cellulose with poly(epsilon-caprolactone) - Synthesis and characterization2008Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 44, nr 9, s. 2991-2997Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In cellulose nanocomposites, the surface of the nanocellulosic phase is critical with respect to nanocellulose dispersion, network formation and nanocomposite properties. Microfibrillated cellulose (MFC) has been grafted with poly(epsilon-caprolactone) (PCL), via ring-opening polymerization (ROP). This changes the surface characteristics of MFC and makes it possible to obtain a stable dispersion of MFC in a nonpolar solvent; it also improves MFC's compatibility with PCL. The thermal behavior of MFC grafted with different amount of PCL has been investigated using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). From TGA measurements, the fraction of PCL in MFC-PCL samples was estimated to 16%, 19%, and 21%. The crystallization and melting behavior of free PCL and MFC-PCL were studied with DSC, and a significant difference was observed regarding melting points, crystallization temperature, degree of crystallinity, as well as the time required for crystallization.

  • 23.
    Mattozzi, Alessandro
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Larsson, Per Tomas
    Hedenqvist, Mikael. S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    n-Hexane sorption in poly(ethylene-co-octene)s: effect on phase composition and character2010Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 46, nr 3, s. 381-388Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Diffusion of small-molecule penetrants in semi-crystalline polymers is retarded by two factors: penetrant detour bypassing impenetrable crystals and the constraining effect of the crystals on the amorphous component. Previous experiments have shown that the latter factor becomes much less important at higher penetrant concentration in the polymer. Structural changes in a series of poly(ethylene-co-1-octene)s occurring on saturation in n-hexane at 296 K, covering a wide range of crystallinity (17–75 wt.%), were studied by wide-angle X-ray scattering, Raman spectroscopy and NMR spectroscopy. Densification of the crystal unit cell and partial dissolution of the interfacial component on n-hexane sorption are the main experimental findings. The conclusion is that the penetrant molecules increase the mobility of the polymer chain segments adjacent to the crystal interface, enabling better packing of the crystal stems and importantly also causes a reduction in the constraining factor (β) for diffusion.

  • 24. Merino, E. G.
    et al.
    Atlas, S.
    Raihane, M.
    Belfkira, A.
    Lahcini, M.
    Hult, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Dionisio, M.
    Correia, N. T.
    Molecular dynamics of poly(ATRIF) homopolymer and poly(AN-co-ATRIF) copolymer investigated by dielectric relaxation spectroscopy2011Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 47, nr 7, s. 1429-1446Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aiming to develop new dielectric polymers containing CN and F groups with strong dipole moments, a novel copolymer of acrylonitrile (AN) and 2,2,2-trifluoroethyl acrylate (ATRIF) was synthesized in acetonitrile by free radical process as well as the respective homopolymer (poly(ATRIF)). The copolymer's composition and microstructure were analyzed by FTIR, (1)H and (13)C NMR spectroscopy and SEC. The molar incorporation of AN determined in the copolymer by NMR was 58 mol%. Thermogravimetric analysis of poly(AN-co-ATRIF) copolymer showed good thermal stability comparatively to the fluorinated homopolymer. Both copolymer, poly(AN-co-ATRIF), and homopolymer, poly(ATRIF), were dielectrically characterized over a frequency range from 10(-1) to 10(6) Hz, and in a temperature range from 223 to 393 K. The dominating relaxation process detected in both materials is the alpha-relaxation, associated with the dynamic glass transition. A VFTH temperature dependence of the relaxation times (tau) was found for both materials, as characteristic of cooperative processes, from which the respective glass transition temperatures (T(g)(tau = 100 s)) were estimated, which differ similar to 40 K, the one of the copolymer being higher (307 K) in accordance to the calorimetric analysis. This effect was attributed to a higher stiffness of the backbone in the copolymer originated by the inclusion of the acrylonitrile groups. Both relaxation functions have the same breath of relaxation times allowing constructing a single master curve, indicating similar non-exponential character. A less fragile behavior was found for the copolymer. This was rationalized in a more straightforward way by the free volume approach instead from a correlation between fragility and intermolecular coupling. It was found that in the copolymer the free volume increases at a lower rate with the temperature increase. It was inferred from the VFTH temperature dependence of the dc conductivity and low values of the decoupling index that ion motion is significantly influenced by the dynamics of the alpha-process.

  • 25.
    Möller, Johanna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Comparison of extraction methods for sampling of low molecular compounds in polymers degraded during recycling2008Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 44, nr 6, s. 1583-1593Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The demand for mechanical recycling of plastic waste results in an increasing amount of recycled polymeric materials available for development of new products. In order for recycled materials to find their way into the material market, high quality is demanded. Thereby, a complete and closed loop of polymeric materials can be achieved successfully. The concept of high quality for recycled plastics imply that besides a pure fraction of e.g. polyethylene (PE) or polypropylene (PP), containing only minor trace amount of foreign plastics, knowledge is required about the type and amount of low molecular weight (LMW) compounds. During long-term use (service-life), products made of polymeric materials will undergo an often very slow degradation where a series of degradation products are formed, in parallel, additives incorporated in the matrix may also degrade. These compounds migrate at various rates to the surrounding environment. The release rate of LMW products from plastics depends on the initiation time of degradation and the degradation mechanisms. For polymers the formation of degradation products may be initiated already during processing, and subsequent use will add products coming from the surrounding environment, e.g. fragrance and aroma compounds from packaging. During recycling of plastics, emissions which contain a series of different LMW compounds may reach the environment leading to unwanted exposure to additives and their degradation residues as well as degradation products of polymers. Several extraction techniques are available for sampling of LMW compounds in polymers before chromatographic analysis. This paper reviews and compares polymer dissolution, accelerated solvent extraction (ASE), microwave assisted extraction (MAE), ultrasound assisted extraction (UAE), super critical fluid extraction (SFE), soxhlet extraction, head-space extraction (HS), head-space solid phase micro extraction (HS-SPME), and head-space stir bar sorptive extraction (HSSE) as appropriate sampling methods for LMW compounds in recycled polymers. Appropriate internal standards useful for these kinds of matrices were selected, which improved the possibility for later quantification. Based on the review of extraction methods, the most promising techniques were tested with industrially recycled samples of HDPE and PP and virgin HDPE and PP for method comparison.

  • 26.
    Nilsson, Fritjof
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Penetrant diffusion in polyethylene spherulites assessed by a novel off-lattice Monte-Carlo technique2009Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 45, nr 12, s. 3409-3417Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Semi-crystalline polymers have a complex hierarchical structure. The purpose of this study was to mimic the real structure of polyethylene spherulites by computer simulation using an off-lattice method in order to predict their diffusion properties. The principles used to build the spherulites were based on established findings obtained by electron microscopy. Spherulites in the crystallinity range of 0-55 vol% were built. Diffusion of small-molecule penetrants assuming no interfacial trapping at the amorphous-crystal boundary was studied using a Monte-Carlo technique. The main findings were: (i) diffusion was isotropic; (ii) diffusion was independent of the aspect ratio of the crystal building bricks, clearly in disagreement with the Fricke model: (iii) the geometrical impedance factor showed a dependence on the average free path length of the penetrant molecules in the amorphous phase: and (iv) data for the geometrical impedance factor obtained by simulation compared favourably with experimental data obtained for several penetrants showing limited interfacial trapping.

  • 27.
    Nordell, Patricia
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Nilsson, Fritjof
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hillberg, Henrik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Water transport in aluminium oxide-poly(ethylene-co-butylacrylate) nanocomposites2011Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 47, nr 12, s. 2208-2215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polymer composites with metal oxide nanoparticles are emerging materials to be used as insulations in electrical applications. However, the extensive interfacial surfaces and the presence of polar groups on the particle surfaces make these composites susceptible to water sorption. Water sorption kinetics data were taken at 23 °C and different relative humidities (18 to 90 %) for composites based on poly(ethylene-co-butyl acrylate) and aluminium oxide; the latter were in three different forms: uncoated and coated with either octyltriethoxy silane or aminopropyl triethoxy silane). The equilibrium water uptake increased in a linear fashion with increasing concentration of polar groups present on the nanoparticle surfaces. Composites with well-dispersed nanoparticles showed a Fickian sorption process with a diffusivity that decreased with increasing filler content. This effect was most pronounced for composites with accessible polar groups on the particle surfaces suggesting that water saturation of the composites is retarded by dual water sorption. Composites that contained a sizeable fraction of large nanoparticle agglomerates showed a two stage sorption process: a fast process associated the saturation of the matrix phase and slow diffusion process due to water sorption of the large nanoparticle agglomerates.

     

  • 28.
    Norström, Emelie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Fogelström, Linda
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Nordqvist, Petra
    Khabbaz, Farideh
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Xylan - A green binder for wood adhesives2015Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, s. 483-493Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wood adhesives are mainly prepared from polymers derived from petroleum-based resources. With the increasing concern for the environment, it is necessary to find alternatives derived from bio-based resources that can replace petroleum-based polymers. To enable this transition it is important that the adhesive properties in terms of bond strength, water resistance and heat resistance are similar, and that the alternative can compete in terms of cost. Hemicelluloses are a byproduct from the pulp industry. From environmental and economic perspectives it is preferable to utilize all components from wood and decrease the amount of low-value byproducts. In this study, hemicelluloses are suggested to be used as binders in wood adhesives, why water dispersions of xylan have been prepared and evaluated. However, xylan itself cannot be used as a wood adhesive due to its limited bonding performance, especially regarding the water resistance. With the addition of dispersing agents, poly(vinyl alcohol) or poly(vinyl amine), and crosslinkers, such as glyoxal or hexa(methoxymethyl) melamine, the xylan dispersions demonstrate promising results. Wood veneers bonded with xylan dispersions and evaluated with ABES, Automated Bonding Evaluation System, demonstrate a good bond strength and surprisingly good water resistance. Several xylan dispersions fulfill the D1 and WATT 91 requirements for wood adhesives according to European Standards EN 204 and EN 14257, exhibiting good bond strength and heat resistance. Xylan dispersed in a poly(vinyl amine) solution also shows remarkable water resistance and reaches the threshold for the D2 criterion according to European Standard EN 204.

  • 29. Pal, Jit
    et al.
    Wu, Duo
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Srivastava, Rajiv K.
    The viscoelastic interaction between dispersed and continuous phase of PCL/HA-PVA oil-in-water emulsion uncovers the theoretical and experimental basis for fiber formation during emulsion electrospinning2017Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 96, s. 44-54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Emulsion electrospinning was recently introduced to minimize the amount of organic solvent during electrospinning process. Here, we uncover the theoretical and experimental basis for the fiber formation in emulsion electrospinning by revealing the viscoelastic interaction between dispersed and continuous phase. Composite electrospun matrices of poly(epsilon-caprolactone) (PCL) with or without hydroxyapatite were devised from an oil-in-water emulsion. The fiber formation and uniformity were clearly governed by the viscoelastic interaction between the continuous and dispersed phase. Caging of droplets by optimal quantity of poly(vinyl alcohol) (PVA) in continuous phase resulted in uniform stretching and coalescence of droplets. An increased storage and loss modulus for emulsions containing optimum PVA manifested desired viscoelastic interaction between dispersed and continuous phase, which further resulted in uniform jet stretching. The visthelasticity of the emulsion could be tailored by changing the polymer concentration in dispersed or continuous phase, which enabled production of electrospun fibers with desired fineness.

  • 30. Ramkumar, D.
    et al.
    Vaidya, U.R.
    Bhattacharya, M.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Properties of injection moulded starch/synthetic polymer blends-I. Effect of processing parameters on physical properties1996Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 32, s. 999-1010Artikkel i tidsskrift (Fagfellevurdert)
  • 31. Salaberria, Asier M.
    et al.
    Labidi, Jalel
    Fernandes, Susana C. M.
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Different routes to turn chitin into stunning nano-objects2015Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 68, s. 503-515Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to its intractable structure and inherent insoluble nature, chitin was for a long time an underutilized resource. The increasing interest in the use of chitin as a source of nanostructured materials is quite recent. This review provides the latest advances in different ways to isolate or fabricate chitin nano-objects - chitin nanocrystals (CHNC) and chitin nanofibers (CHNF) - from different chitin sources. It also summarizes the chronology of some important scientific advances on chitin research during its 200 years of history. Additionally, engineered composite materials based on chitin nano-objects are reviewed.

  • 32.
    Sanandaji, Nima
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Bretzler, Victor
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Schmelter, S.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Confined space crystallisation of poly(epsilon-caprolactone) in controlled pore glasses2013Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 49, nr 8, s. 2073-2081Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of controlled pore glasses (CPGs) with pore diameters ranging from 10 nm to 293 nm were impregnated with three poly(epsilon-caprolactone)s (PCL) differing in number average molar mass (10-80 kDa), and their crystallisation kinetics were studied with differential scanning calorimetry. Scanning electron microscopy and thermogravimetry confirmed that the polymers were mainly housed within the pore channels. The PCLs housed in the CPG with the finest pores (10 nm) showed a markedly different crystallisation behaviour from that of the corresponding bulk pristine polymers: a significantly slower crystallisation, a low Avrami exponent (<1), a higher product of the surface free energies of the fold and lateral surfaces of the formed PCL crystals and a lower initial melting peak temperature. This behaviour of confinement was similar for the three PCLs studied. In the CPGs with wider pore channels (23-293 nm), the PLCs showed essentially the same crystallisation kinetics as the pristine polymers. These differences in the crystallisation kinetics were attributed to the confinement, i.e. to the small available volume with respect to crystal size and to interactions with the pore walls. The results obtained suggest that the initial stages of crystallisation, presumably including other crystal phases or mesophases, occurred according to different paths for bulk PCL and for PCL housed in narrow nanopores.

  • 33.
    Sanandaji, Nima
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Oko, A.
    YKI, Ytkemiska Institutet AB, Institute for Surface Chemistry, Sweden.
    Haviland, David B.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Nanostrukturfysik.
    Tholén, E.
    Intermodulation Products AB.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Inkjet printing as a possible route to study confined crystal structures2013Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 49, nr 1, s. 203-208Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Inkjet printing is a technique for the precise deposition of liquid droplets in the pL-volume range in well-defined patterns. Previous studies have shown that inkjet printing is attractive in polymer technology since it permits the controlled deposition of functional polymer surfaces. We suggest that the technique might also be useful for studying crystallization, in particular confined crystallization. Inkjet printing is a non-contact deposition method with minimal risk of contamination, which allows the exact deposition of both polymer solutions and polymer melts. This paper demonstrates the possibility of utilizing the technique to create surfaces where polymer chains form isolated small structures. These structures were confined by both the low polymer content in each droplet and the time constraint on crystal formation that arose as the result of the rapid solvent evaporation from the pL-sized droplets. In theory, inkjet printing enables the exact deposition of systems with as few as a single polymer chain in the average droplet. With appropriate instrumentation, the versatile inkjet technology can be utilized to create whole surfaces covered with polymer structures formed by the crystallization of small, dilute and rapidly evaporating droplets. 110 pL droplets of a 10 -6 g L -1 poly(ε-caprolactone) solution in 1-butanol have been deposited and studied by atomic force microscopy. Small structures of ca. 10 nm thickness and ca. 50 nm diameter also seemed to exhibit crystalline features. Some of the small structures had unusual rectangular forms whilst others were interpreted to be early precursors to six-sided single crystals previously observed for poly(ε-caprolactone). The unusual forms observed may have resulted from the entrapment of crystal structures into metastable phases, due to the limited amount of polymer material present and the rapid evaporation of the droplets.

  • 34.
    Srivastava, Rajiv
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Kumar, K.
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Delhi.
    Varma, I. K.
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Delhi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Chemo-enzymatic synthesis of comb polymers2007Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 43, nr 3, s. 808-817Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper describes the synthesis and characterization of comb polymers by a two-step chemo-enzymatic process. In the first step macromonomers bearing unsaturation at the chain end were prepared by lipase catalyzed ring-opening polymerization (ROP) of E-caprolactone (CL) and 1,5-dioxepane-2-one (DXO). The ROP was carried out in bulk at 60 degrees C under anhydrous conditions using 2-hydroxyethyl methacrylate (HEMA) as the initiator. The DP of the macromonomers was controlled by regulating the monomer: HEMA molar feed concentration. The macromonomers were then homo- or co-polymerized in the second step with alkyl methacrylate monomers (methyl methacrylate or HEMA) using AIBN initiated free radical polymerization. Characterization of the polymers was done by H-1 NMR, SEC and DSC techniques.

  • 35.
    Strandberg, Clara
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Burman, Lina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Total Luminescence Intensity (TLI) Offers Superior Early Oxidation Detection in Unstabilised Polyethylene but is no better than FT-IR for Stabilised Polyolefins2006Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 42, nr 8, s. 1855-1865Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In an earlier study, we have shown that chemiluminescence (CL) and the total luminescence intensity (TLI) method are highly sensitive to oxidation in degradable PE. In this study, stabilised PE and PP were characterised with CL in an inert (TLI) and in an oxygen atmosphere (CL-OIT) and the results were compared to those obtained by the commonly used techniques, FT-IR (carbonyl index (CI)) and thermal analysis (DSC-OIT). PE was aged at a low temperature (80 degrees C) and PP was aged at temperatures between 60 and 120 degrees C. Non-Arrhenius behaviour was observed in the oxidation of PP. This showed the importance of aging at a low temperature to obtain realistic results. TLI and Cl of stabilised PP and most of the stabilised PE gave comparable results with the same sensitivity for oxidation detection. This was in contrast to our previous results for degradable PE. However, TLI of unstabilised PE showed earlier oxidation detection than Cl, which agreed with our earlier results. TLI of PE had a higher sensitivity than CL-OIT, and both TLI and Cl of PP were sufficiently sensitive to detect the effect of aging at different temperatures, whereas DSG-OIT was not.

  • 36.
    Tsai, Wen-Chung
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Laiback, Åsa
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Melin, H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ngo, M.
    Trollsas, M.
    Gedde, Ulf
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Physical changes and sorption/desorption behaviour of amorphous and semi-crystalline PLLA exposed to water, methanol and ethanol2016Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 76, s. 278-293Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to study the effects of water, methanol and ethanol on the structure of fully amorphous and semi-crystalline poly(L-lactic acid) (PLLA), which is important for applications in which the material is in contact with body fluids (water), and also in order to tailor properties by adjusting the crystallinity and glass transition temperature using penetrants. Amorphous and semi-crystalline PLLA tubes were exposed to the afore-mentioned liquids at 37 degrees C and the mass crystallinity, fictive temperature and the rigid amorphous fraction were assessed by DSC and WAXS. The diffusivity and solubility of the penetrant were assessed by gravimetric sorption and desorption experiments. Water has a plasticizing effect on the glassy structure, which enhances the equilibration of the glass as revealed by a lowering of the fictive temperature of the subsequently dried samples, but the plasticization was not sufficient to induce cold-crystallisation. The moderate effect of water at 37 degrees C was further demonstrated by the almost constant water diffusivity. Both methanol and ethanol induced cold-crystallisation at 37 degrees C, primarily forming crystals of the alpha'-form, which in the case of methanol led to a marked increase in the fictive temperature and the formation of a rigid amorphous fraction in the subsequent dried samples. The crystal growth was restricted according to an Avrami analysis of the crystallisation kinetics data. The complexity of the sorption and desorption kinetics of methanol and ethanol was caused by the progressing cold-crystallisation on sorption, which resulted in several phenomena. Very notable was the extremely high concentration-dependence of the penetrant diffusivity as revealed on, desorption, which could not be explained by plasticization alone. Instead it is believed that the formed crystals caged a significant fraction of the penetrant molecules.

  • 37.
    Utsel, Simon
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Carlmark, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Bergström, Magnus
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Malmström, Eva E.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Synthesis, adsorption and adhesive properties of a cationic amphiphilic block copolymer for use as compatibilizer in composites2012Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 48, nr 7, s. 1195-1204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, the objective was to synthesize a compatibilizer that can electrostatically adsorb onto cellulose fibers, in fiber-based composites, to enhance the interaction between the fibers and non-polar polymer matrices. This physical route to attach the compatibilizer onto and thereby modify a fiber surface is convenient since it can be performed in water under mild conditions. Polystyrene (PS) was used for the high molecular weight, non-polar, block and poly(dimethylamino)ethyl methacrylate (PDMAEMA) was used as the polar block, which was subsequently quaternized to obtain cationic charges. The block copolymer self-assembles in water into cationic micelles and the adsorption to both silicon oxide surfaces and cellulose model surfaces was studied. The micelles spread out on the surface after heat treatment and contact angle measurements showed that the contact angles against water increased significantly after this treatment. AFM force measurements were performed with a PS probe to study the adhesive properties. The adhesion increased with increasing contact time for the treated surfaces, probably due to entanglements between the polystyrene blocks at the treated surface and the probe. This demonstrates that the use of this type of amphiphilic block copolymer is a promising route to improve the compatibility between charged reinforcing materials, such as cellulose-based fibers/fibrils, and hydrophobic matrices in composite materials.

  • 38.
    Vamvounis, George
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Jonsson, Magnus
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Malmström, Eva
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Hult, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Synthesis and properties of poly(3-n-dodecylthiophene) modified thermally expandable microspheres2013Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 49, nr 6, s. 1503-1509Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Functionalization of thermally expandable microspheres (TEMs) with a conjugated polymer is explored. These functionalized thermally expandable microspheres were prepared by grafting 3-n-dodecylthiophene via oxidative polymerization from a thiophene modified TEM. The thiophene modified TEM to 3-n-dodecylthiophene ratio was varied during grafting and the resulting poly(3-n-dodecylthiophene) grafted TEM were characterized by FT-IR spectroscopy, Thermal Gravimetric Analysis, Scanning Electron Microscopy, Thermo-Mechanical Analysis and X-ray diffraction. The particles were approximately 30 pm in diameter and upon heating, the functionalized microspheres expanded up to 50 times. This expansion property was related to the poly(3-n-dodecylthiophene) content, where the increase in poly(3-n-dodecylthiophene) on microsphere decreased the thermal expansion. The X-ray diffraction shows a sharpening of the poly(3-n-dodecylthiophene) (I 0 0) diffraction peak upon expansion. Grafting conjugated polymers to thermally expandable microspheres provides robust functional photo- and electro-active TEMs.

  • 39.
    Vilaplana, Francisco
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Ribes-Greus, Amparo
    Univ. Politecn., Valencia.
    Changes in the microstructure and morphology of high-impact polystyrene subjected to multiple processing and thermo-oxidative degradation2007Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 43, nr 10, s. 4371-4381Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multiple processing and thermo-oxidation have been employed to simulate the degradative processes to which high-impact polystyrene (HIPS) is subjected during processing, service life, and mechanical recycling. A curve-fitting procedure has been proposed for the analysis of the individual bands corresponding to polybutadiene microstructure resulting from Raman spectroscopy. The analysis of the glass transition relaxations associated with the polybutadiene (PB) and polystyrene (PS) phases has been performed according to the free-volume theory. Both reprocessing and thermo-oxidative degradation are responsible for complex physical and chemical effects on the microstructure and morphology of PB and polystyrene PS phases, which ultimately affect the macroscopic performance of HIPS. Multiple processing affects PB microstructure and the free-volume parameter associated with the PS phase. Physical ageing of the PS phase predominates for shorter exposure to thermo-oxidation; after prolonged exposure, however, the chemical effects on the PB phase become significant and strongly influence the overall structure.

  • 40.
    Willgert, Markus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Kjell, Maria H.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Jacques, Eric
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, N. Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Johansson, Mats
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Ytbehandlingsteknik.
    Photoinduced free radical polymerization of thermoset lithium battery electrolytes2011Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 47, nr 12, s. 2372-2378Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Series of solid poly(ethylene oxide)-methacrylate electrolytes have successfully been manufactured with an aim to serve in a multifunctional battery both as mechanical load carrier as well as lithium ion conductor. The electrolytes produced, in a solvent free process with no post cure swelling, hold a broad range of both mechanical as well as ion conducting properties. The monomer and Li-salt mixtures have been irradiated with UV light, initiating free radical polymerization to obtain solid smooth, homogenous specimens to be utilized as ion conducting electrolytes. The storage modulus at 20 degrees C is ranging from 1 MPa to almost 2 GPa. The conducting ability of the electrolyte ranges from 5.8 x 10(-10) up to 1.5 x 10(-6) S/cm. These large variations in both mechanical properties as well as ionic conductivity are discussed, but also the versatility within the production technique is emphasized.

  • 41.
    Wistrand, Ingemar
    et al.
    STFI-Packforsk AB.
    Lingström, Rikard
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Preparation of electrically conducting cellulose fibres utilizing polyelectrolyte multilayers of poly(3,4-ethylenedioxythiophene): poly(styrene sulphonate) and poly(allyl amine)2007Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 43, nr 10, s. 4075-4091Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The primary goal with this work is to create electrically conductive cellulose fibres, this has been done to explore possible new applications for fibre based material. This research uses various methods to create polyelectrolyte multilayers (PEMs) on bleached softwood fibres and on SiO2 model surfaces, by sequentially treating these materials with poly(3,4ethylenedioxythiophene):poly(styrene sulphonate) (PEDOT:PSS) and poly(allyl amine) (PAH). Paper sheets were then produced from the PEM-modified pulp and evaluated in terms of tensile strength, adsorbed amount of polymer, and electrical conductivity. To evaluate the influence of fibre charge on the measured paper properties, pulps of two different initial fibre charge densities were prepared via carboxymethylation. Because of the bluish colour of PEDOT:PSS, the build-up of PEM could be easily followed, since the fibres grew increasingly darker blue throughout the modification sequence. The conductivity of the fibre network increased by 2-3 orders of magnitude when the pulp of a higher fibre charge density was used. This suggests that it is more important to create a fibrous network with a high fibre-fibre joint strength and a large total joined area in the sheet rather than to maximize the adsorbed amount of PEDOT:PSS. A difference in conductivity could also be noted depending on the polyelectrolyte adsorbed in the outer layer, PAH lowered the conductivity compared to PEDOT:PSS. Evaluating the mechanical properties revealed that the use of PEDOT:PSS reduces the tensile strength of the paper. When five double layers had been adsorbed onto the carboxymethylated sample in which PEDOT:PSS formed the outer layer, calculations indicated a 25% decrease in tensile strength compared to that of reference material without PEMs. ESEM studies indicate that PEM treatment produces a significantly changed and somewhat smoother fibre surface.

  • 42.
    Wu, Duo
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Recycling PLA to multifunctional oligomeric compatibilizers for PLA/starch composites2015Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 64, s. 126-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Simple one-pot valorization of poly(lactic acid) (PLA) to green additives was demonstrated. PLA was thermally recycled in the presence of polyols, which accelerated the degradation process by reacting with PLA chains. As a result low molecular weight oligomers with polyols end-groups were formed. The reaction between PLA and multifunctional alcohols i.e. glycerol, sorbitol, glucose and starch were confirmed by FTIR, H-1 NMR, SEC and MALDI-MS. The resulting amphiphilic products were evaluated as compatibilizer candidates for PLA/starch blends. Multiple techniques demonstrated that the obtained oligomers strengthened the interfacial adhesion and improved the compatibility and flexibility of extruded and melt-blended PLA/starch composites. The developed one-pot procedure required no solvent or catalyst offering good possibilities for up-scaling. It was, thus, demonstrated that PLA can be recycled to low molecular weight compatibilizers by simple process of thermal heating in the presence of polyols. This provides profound promise for retaining the material value of old PLA products at the same time as biobased additives are produced.

  • 43.
    Yin, Bo
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Aminlashgari, Nina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Yang, Xi
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Glucose esters as biobased PVC plasticizers2014Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 58, s. 34-40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Utilization of glucose, produced by liquefaction of cellulose or other abundant biomass sources, as raw material for production of green plasticizers would offer an attractive alternative to traditional phthalate plasticizers. Three glucose hexanoate esters (GHs) were synthesized by one-step reaction and evaluated as green plasticizers for poly(vinyl chloride) (PVC). The esterification was carried out for three different time periods to obtain plasticizers with different number of hexanoate groups, as the degree of substitution could influence the miscibility between PVC and GHs. A fast and powerful laser desorption ionization-mass spectrometry (LDI-MS) method was developed to obtain molecular level structural information of the plasticizer structures. All the GHs showed good miscibility with PVC and the GH blends exhibited better mechanical properties, in the form of higher strain at break and lower modulus, as compared to glucose pentaacetate (GPA) and sucrose octaacetate (SOA) blends that were studied in comparison. Altogether the results indicate that the synthesized glucose esters have large potential as green PVC plasticizers and they could be a promising option to overcome the environmental problems caused by phthalate plasticizers.

  • 44.
    Zhu, Jiqing
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Kringos, Niki
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Polymer modification of bitumen: Advances and challenges2014Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 54, nr 1, s. 18-38Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Advances and challenges in the field of bitumen polymer modification for road construction during the last 40 years are reviewed in this paper. The history of bitumen polymer modification is described chronologically. Some popular plastomers and thermoplastic elastomers in bitumen modification are discussed regarding their advantages and disadvantages, including polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate (EVA), ethylene-butyl acrylate (EBA), styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS) and styrene-ethylene/butylene-styrene (SEBS). Although these polymers all improve bitumen properties to some extent, there are still some drawbacks limiting the future development of bitumen polymer modification, such as high cost, low ageing resistance and poor storage stability of polymer modified bitumen (PMB). Researchers attempted various ways to remove these drawbacks. Some technical developments for removing drawbacks are reviewed in this paper, including saturation, sulfur vulcanization, adding antioxidants, using hydrophobic clay minerals, functionalization and application of reactive polymers. The future development of polymers for bitumen modification is analyzed as well. Since it is currently challenging to perfectly achieve all expected PMB properties at the same time, some compromised recommendations are given in this paper, among which greatly enhancing the properties with an acceptably high cost, significantly reducing the cost with relatively poor properties and their combinations. Functionalization is emphasized as a promising way to enhance the properties of currently used polymers and develop new-type polymer modifiers with much greater success in the future. It is also recommended that future research on bitumen polymer modification focuses more on function development towards enhancing: adhesion with aggregates, long-term performance and recyclability.

  • 45. Çakir, S.
    et al.
    Eriksson, Magnus
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Martinelle, Mats
    KTH, Skolan för bioteknologi (BIO), Industriell bioteknologi.
    Koning, C. E.
    Multiblock copolymers of polyamide 6 and diepoxy propylene adipate obtained by solid state polymerization2016Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 79, s. 13-22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polyesteramide multiblock copolymers based on polyamide 6 and diepoxy propylene adipate blocks were synthesized. For this purpose a carboxyl-terminated polyamide 6 (Mn = 2400 g/mol, Tm = 205.5 °C) and diepoxy propylene adipate (Mn = 450 g/mol) were separately synthesized and characterized. The incorporation of the oligoester into the polyamide 6 backbone was performed by solid state polymerization (SSP) well below the melting temperature of the polyamide (80-140 °C) so that the physical and thermal properties of the original polyamide 6 block were retained. Formation of the multiblock structure was confirmed by following the increase in molecular weight by SEC, reaction of the end groups by 1H NMR and by following the maintained melting temperature after the copolymerization. These segmented copolymers have molecular weights up to 10 kg/mol, thermal stability of 325 °C at 5% weight loss and a melting temperature of 205 °C.

1 - 45 of 45
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