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  • 1.
    Marcioni, Massimo
    et al.
    Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Alessandria Site, Viale Teresa Michel 5, 15121, Alessandria, Italy.
    Zhao, Mengxiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Maddalena, Lorenza
    Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Alessandria Site, Viale Teresa Michel 5, 15121, Alessandria, Italy.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Avolio, Roberto
    Institute for Polymers, Composites and Biomaterials, Italian National Research Council -Via Campi Flegrei 34, 80078 Pozzuoli, NA, Italy.
    Castaldo, Rachele
    Institute for Polymers, Composites and Biomaterials, Italian National Research Council -Via Campi Flegrei 34, 80078 Pozzuoli, NA, Italy.
    Gentile, Gennaro
    Institute for Polymers, Composites and Biomaterials, Italian National Research Council -Via Campi Flegrei 34, 80078 Pozzuoli, NA, Italy.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Carosio, Federico
    Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Alessandria Site, Viale Teresa Michel 5, 15121, Alessandria, Italy.
    Flame-retardant Lightweight materials from layer-by-layer coated cellulose fibersManuscript (preprint) (Other academic)
    Abstract [en]

    Cellulose fibers were functionalized using the layer-by-layer approach, which allows for the formation of a coating by positively and negatively charged layers of polyelectrolytes on the fiber surface, consisting of sodium hexametaphosphate and chitosan. By using this coating approach, it was possible to obtain a bio-based, homogeneous and flame-retardant coating. Self-extinguishing properties was achieved at 1 bi-layer (BL) as visible in a horizontal flame test, while non-ignitability was obtained after 3BL coating. The coated cellulose fibers were used to produce foams, a self-standing lightweight 3D structure, by freeze-drying. Even though made by mainly cellulose, these foams gave self-extinguishing results when prepared by 1BL coated fibers and non-ignitability when prepared with 3BL coated fibers. Cone calorimetry showed a decrease in heat release rate and total heat release of 56% and 68% respectively for the foam containing 3BL coated fibers.

  • 2.
    Marcioni, Massimo
    et al.
    Politecn Torino, Dipartimento Sci Applicata & Tecnol, I-15121 Alessandria, Italy..
    Zhao, Mengxiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Maddalena, Lorenza
    Politecn Torino, Dipartimento Sci Applicata & Tecnol, I-15121 Alessandria, Italy..
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Avolio, Roberto
    Italian Natl Res Council, Inst Polymers Composites & Biomat, I-80078 Naples, Italy..
    Castaldo, Rachele
    Italian Natl Res Council, Inst Polymers Composites & Biomat, I-80078 Naples, Italy..
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Carosio, Federico
    Politecn Torino, Dipartimento Sci Applicata & Tecnol, I-15121 Alessandria, Italy..
    Layer-by-Layer-Coated Cellulose Fibers Enable the Production of Porous, Flame-Retardant, and Lightweight Materials2023In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 15, no 30, p. 36811-36821Article in journal (Refereed)
    Abstract [en]

    New sustainable materialsproduced by green processing routes arerequired in order to meet the concepts of circular economy. The replacementof insulating materials comprising flammable synthetic polymers bybio-based materials represents a potential opportunity to achievethis task. In this paper, low-density and flame-retardant (FR) porousfiber networks are prepared by assembling Layer-by-Layer (LbL)-functionalizedcellulose fibers by means of freeze-drying. The LbL coating, encompassingchitosan and sodium hexametaphosphate, enables the formation of aself-sustained porous structure by enhancing fiber-fiber interactionsduring the freeze-drying process. Fiber networks prepared from 3 Bi-Layer(BL)-coated fibers contain 80% wt of cellulose and can easily self-extinguishthe flame during flammability tests in vertical configuration whiledisplaying extremely low combustion rates in forced combustion tests.Smoke release is 1 order of magnitude lower than that of commerciallyavailable polyurethane foams. Such high FR efficiency is ascribedto the homogeneity of the deposited assembly, which produces a protectiveexoskeleton at the air/cellulose interface. The results reported inthis paper represent an excellent opportunity for the developmentof fire-safe materials, encompassing natural components where sustainabilityand performance are maximized.

  • 3.
    Zhao, Mengxiao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Study of Paper Dry Strength Additives on Cellulose Fibres2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Paper packaging is commonly found in the form of paper and cardboard boxes, but recently paper packing is being used in food packaging, trays, beverage packaging and even paper straws, among others. Paper strength additives have been developed to increase the efficiency of the joint strength and the joint areas and potentially maintain bulk in paper products. In this thesis, a fundamental study of paper dry strength additives was performed involving kraft birch fibres and model cellulose materials to explore the interaction between strength additives and cellulose fibres. The same techniques used in paper strength additives were extended to the adsorption of fire-retardant polymers on fibres. 

    Adsorption behaviours of cationic starch (CS) and anionic polyacrylamide (APAM) or anionic polyelectrolyte complexes (PECs) were studied on kraft birch fibres with different surface charges. It was found that the saturation adsorption of CS on birch fibres in 0.01 M NaCl showed a linear relationship with the surface charge of fibre, while the adsorption of APAM and PECs was independent of the surface charge of fibres. Higher surface charge of fibres expands the saturation adsorption capacity of strength additives, consequently, improves the tensile strength properties of handsheets made of kraft birch fibres with CS/APAM or CS/PECs. Bending stiffness of handsheets was improved by CS and boosted by PECs or APAM. In addition, sheet density was not significantly compromised by adding strength additives. Cationic strength additives were investigated on model cellulose surfaces, model cellulose nanofibrils filaments, and model cellulose beads. CSs produced an increase in the mass of the cellulose surface, while cationic PAMs led to a decrease in the total mass of cellulose surface determined by Quartz Crystal Microbalance with Dissipation monitoring. All types of strength additives affected the filament joints but in different ways, while most of them made filaments form intermixed interphases in the joints. The adsorption of chitosan and sodium hexamethaphosphate increased steadily and formed three bilayers on cellulose fibres. These materials formed stable lightweight materials after freeze-drying suspensions of the coated fibers containing them and show good fire retardant properties.

    The fundamental study of paper dry strength additives and other polymers on the cellulose fibres can facilitate the development of new polymers for wood fibre-based materials. 

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  • 4.
    Zhao, Mengxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Asta, Nadia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Reid, Michael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Robertsén, Leif
    Kemira R&D Center, Luoteisrinne 2, 02270 Espoo, Finland.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Exploration of the molecular mechanisms behind paper strength additives using model cellulose surfaces, filaments and beadsManuscript (preprint) (Other academic)
  • 5.
    Zhao, Mengxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. Kemira R&D Center, Luoteisrinne 2, Espoo, 02270, Finland.
    Robertsén, Leif
    Kemira R&D Center, Luoteisrinne 2, Espoo, 02270, Finland.
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Adsorption of paper strength additives to hardwood fibres with different surface charges and their effect on paper strength2022In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 29, no 4, p. 2617-2632Article in journal (Refereed)
    Abstract [en]

    Light-weight paper products that contain less fibres, but with a maintained bulk and improved strength properties, are highly desirable due to the low cost of raw materials and improved logistics of packaged goods. In this respect, the adsorption capacity of dry strength additives onto fibres, which is affected by the surface charge of said fibres, is very important for the development of these mechanically robust paper products. The influence of the surface charge on the adsorption of strength additives was investigated for, dissolving grade fibres, kraft fibres and kraft fibres modified with carboxymethyl cellulose (CMC) with different surface charge densities, but the same fibre dimensions. The strength additives investigated were cationic starch (CS), anionic polyacrylamide (APAM) and polyelectrolyte complexes (PECs), containing CS and APAM. A linear relationship was found between the surface charge of the fibres and the saturated adsorbed amount of CS. However, when either APAM or PECs adsorbed as secondary layers onto the CS, no correlation between cellulose charge and the saturation adsorption could be observed. The adsorption of APAM was dramatically affected by the pre-adsorbed amount of CS, whereas PECs were less influenced. Moreover, the additives improved the tensile strength (60%) and strain at break (> 100%) of handsheets formed with the kraft fibres and adsorbed APAM. It was also found that CS/APAM increased the sheet density while CS/PECs lowered it. In conclusion, the gained fundamental understanding of these adsorption of additives is of significant importance to facilitate the industrial development of sustainable low-cost high-end packaging products. Graphical abstract: [Figure not available: see fulltext.]

  • 6.
    Zhao, Mengxiao
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Robertsén, Leif
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Pettersson, Torbjörn
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Effect of saturation adsorption of paper strength additives on the performance of paper2022In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 4, p. 624-635Article in journal (Refereed)
    Abstract [en]

    The use of paper dry strength additives is oneof the methods for producing packaging boards with alower grammage while maintaining mechanical properties.In the present work, papers were formed using dissolvinggrade kraft fibres, kraft fibres and carboxymethylatedcellulose (CMC) modified kraft fibres (C-kraft fibres),with either cationic starch (CS), anionic polyacrylamide(APAM) or anionic polyelectrolyte complexes (PECs). Fibresand sheets were characterized to evaluate how the saturationadsorption of the different strength additives influencesthe properties of the treated fibres and the finalhandsheets. The tensile index of papers made from C-kraftfibres was the highest due to the highest adsorption capacityof strength additives. Moreover, the strength additivesincreased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %.Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significantimprovement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, theknowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties.

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1 - 6 of 6
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