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Surface grafting of microfibrillated cellulose with poly(epsilon-caprolactone) - Synthesis and characterization
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.ORCID iD: 0000-0001-7132-3251
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.ORCID iD: 0000-0001-5818-2378
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.ORCID iD: 0000-0002-8348-2273
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2008 (English)In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 44, no 9, 2991-2997 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
2008. Vol. 44, no 9, 2991-2997 p.
Keyword [en]
Microfibrillated cellulose, Grafting of poly(epsilon-caprolactone), Ring-opening polymerization, Thermal gravimetric analysis, Differential scanning calorimetry, Dispersion, NONISOTHERMAL CRYSTALLIZATION, NANOCOMPOSITE MATERIALS, WHISKERS, FIBERS, BEHAVIOR, POLYCAPROLACTONE, BIOPOLYMERS, SUSPENSIONS, COPOLYMERS
National Category
Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:kth:diva-13468DOI: 10.1016/j.eurpolymj.2008.06.023ISI: 000260274400031Scopus ID: 2-s2.0-51149086166OAI: oai:DiVA.org:kth-13468DiVA: diva2:325503
Note
QC20100618Available from: 2010-06-18 Created: 2010-06-18 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Ring-opening polymerization from cellulose for biocomposite applications
Open this publication in new window or tab >>Ring-opening polymerization from cellulose for biocomposite applications
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There is an emerging interest in the development of sustainable materials with high performance. Cellulose is promising in this regard as it is a renewablere source with high specific properties, which can be utilized as strong reinforcements in novel biocomposites. However, to fully exploit the potential ofcellulose, its inherent hydrophilic character has to be modified in order toimprove the compatibility and interfacial adhesion with the more hydrophobicpolymer matrices commonly used in composites.In this study, the grafting of poly(ε-caprolactone) (PCL) and poly(L-lactide)(PLLA) from cellulose surfaces, via ring-opening polymerization (ROP) of ε-caprolactone and L-lactide, was investigated. Both macroscopic and nano-sizedcellulose were explored, such as filter paper, microfibrillated cellulose (MFC),MFC-films, and regenerated cellulose spheres. It was found that thehydrophobicity of the cellulose surfaces increased with longer graft lengths, andthat polymer grafting rendered a smoother surface morphology.To improve the grafting efficiency in the ROP from filter paper, both covalent(bis(methylol)propionic acid, bis-MPA) and physical pretreatment (xyloglucanbisMPA)were explored. The highest grafting efficiency was obtained with ROPfrom the bis-MPA modified filter papers, which significantly increased amountof polymer on the surface, i.e. the thickness of the grafted polymer layer.MFC was grafted with PCL to different molecular weights. The dispersability innon-polar solvent was obviously improved for the PCL grafted MFC, incomparison to neat MFC, and the stability of the MFC suspensions was better maintained with longer grafts. PCL based biocomposites were prepared from neat MFC and PCL grafted MFCwith different graft lengths. The polymer grafting improved the mechanical properties of the composites, and the best reinforcing effect was obtained when PCL grafted MFC with the longest grafts were used as reinforcement.A bilayer laminate consisting of PCL and MFC-films grafted with different PCL graft lengths displayed a gradual increase in the interfacial adhesion with increasing graft length.The effect of grafting on the adhesion was also investigated via colloidal probeatomic force microscopy at different temperatures and time in contact. A significant improvement in the adhesion was observed after polymer grafting.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 68 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2009:24
Keyword
cellulose, ring-opening polymerization, polycaprolactone, grafting from
National Category
Other Basic Medicine
Identifiers
urn:nbn:se:kth:diva-10455 (URN)978-91-7415-338-5 (ISBN)
Public defence
2009-06-05, F3, KTH, Lindstedsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100730Available from: 2009-05-18 Created: 2009-05-15 Last updated: 2010-07-30Bibliographically approved
2. Polymer Nanocomposites in Thin Film Applications
Open this publication in new window or tab >>Polymer Nanocomposites in Thin Film Applications
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The introduction of a nanoscopic reinforcing phase to a polymer matrix offers great possibilities of obtaining improved properties, enabling applications outside the boundaries of traditional composites.

The majority of the work in this thesis has been devoted to polymer/clay nanocomposites in coating applications, using the hydroxyl-functional hyperbranched polyester Boltorn® as matrix and montmorillonite clay as nanofiller. Nanocomposites with a high degree of exfoliation were readily prepared using the straightforward solution-intercalation method with water as solvent. Hard and scratch-resistant coatings with preserved flexibility and transparency were obtained, and acrylate functionalization of Boltorn® rendered a UV-curable system with similar property improvements. In order to elucidate the effect of the dendritic architecture on the exfoliation process, a comparative study on the hyperbranched polyester Boltorn® and a linear analogue of this polymer was performed. X-ray diffraction and transmission electron microscopy confirmed the superior efficiency of the hyperbranched polymer in the preparation of this type of nanocomposites.

Additionally, an objective of this thesis was to investigate how cellulose nanofibers can be utilized in high performance polymer nanocomposites. A reactive cellulose “nanopaper” template was combined with a hydrophilic hyperbranched thermoset matrix, resulting in a unique nanocomposite with significantly enhanced properties. Moreover, in order to fully utilize the great potential of cellulose nanofibers as reinforcement in hydrophobic polymer matrices, the hydrophilic surface of cellulose needs to be modified in order to improve the compatibility. For this, a grafting-from approach was explored, using ring-opening polymerization of ε-caprolactone (CL) from microfibrillated cellulose (MFC), resulting in PCL-modified MFC. It was found that the hydrophobicity of the cellulose surfaces increased with longer graft lengths, and that polymer grafting rendered a smoother surface morphology. Subsequently, PCL-grafted MFC film/PCL film bilayer laminates were prepared in order to investigate the interfacial adhesion. Peel tests demonstrated a gradual increase in the interfacial adhesion with increasing graft lengths.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 66 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2010:12
Keyword
Nanocomposites, hyperbranched polymers, montmorillonite, clay nanoparticles, exfoliated, coatings, crosslinking, TEM, XRD, mechanical properties, thermal properties, cellulose nanofibers, Atom Transfer Radical Polymerization, Ring-Opening Polymerization, poly(ε-caprolactone), surface modification, grafting, interfacial adhesion
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-12400 (URN)978-91-7415-615-7 (ISBN)
Public defence
2010-05-07, D1, Lindstedtsvägen 17, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC20100621Available from: 2010-04-20 Created: 2010-04-16 Last updated: 2012-03-28Bibliographically approved

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Fogelström, LindaBerglund, LarsMalmström, EvaHult, Anders

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