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  • 1.
    Correia, Viviane da Costa
    et al.
    Department of Biosystems Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo.
    Santos, Vlademir dos
    Department of Biosystems Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Santos, Sergio Francisco
    Department of Materials and Technology, Faculty of Engineering, São Paulo State University.
    Leão, Alcides Lopes
    Department of Rural Engineering, Sao Paulo State University.
    Junior, Holmer Savastano
    Department of Biosystems Engineering, Faculty of Animal Science and Food Engineering, University of São Paulo.
    Grinding process for the production of nanofibrillated cellulose based on unbleached and bleached bamboo organosolv pulp2016Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 5, s. 2971-2987Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanofibrillated cellulose (NFC) is a type of nanomaterial based on renewable resources and produced by mechanical disintegration without chemicals. NFC is a potential reinforcing material with a high surface area and high aspect ratio, both of which increase reinforcement on the nanoscale. The raw materials used were unbleached and bleached bamboo organosolv pulp. Organosolv pulping is a cleaner process than other industrial methods (i.e. Kraft process), as it uses organic solvents during cooking and provides easy solvent recovery at the end of the process. The NFC was produced by treating unbleached and bleached bamboo organosolv pulps for 5, 10, 15 and 20 nanofibrillation cycles using the grinding method. Chemical, physical and mechanical tests were performed to determine the optimal condition for nanofibrillation. The delamination of the S2 layer of the fibers during nanofibrillation contributed to the partial removal of amorphous components (mainly lignin), which have low polarity and improved the adhesion of the fibers, particularly the unbleached cellulose. The transverse modulus of elasticity of the unbleached NFC was highest after 10 nanofibrillation cycles. Further treatment cycles decreased the modulus due to the mechanical degradation of the fibers. The unbleached NFC produced by 10 cycles have a greater transverse modulus of elasticity, the crystallite size showed increase with the nanofibrillation, and after 5 nanofibrillation cycles, no differences are observed in the morphology of the fibers.

  • 2.
    Frisk, Nikolina
    et al.
    Luleå tekniska universitet. Centre for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto, Toronto, Canada.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Centre for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto, Toronto, Canada.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Centre for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto, Toronto, Canada.
    Nanocellulose reinforced bio-polyurethane foams as core in sandwich composite panels2017Ingår i: ICCM21 Proceedings, ICCM, International Committee on Composite Materials , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    The aim of this work was to reinforce bio-polyurethane (BPU) with cellulose nanofibers (CNF) to develop foams suitable for use as core in lightweight composite panels. The nanofibers were prepared using mechanical grinding of bleached carrot juice residue, a cheap and energy efficient process. The prepared foam properties were studied and compared to neat BPU foam properties. The results showed that the CNF reinforced foam had better mechanical properties compared to the neat bio-PU foams and the addition of cellulose nanofibers deceased the cell size and open cell content. Then the foam suitability for composite use was evaluated by manufacturing lightweight sandwich panels using vacuum infusion process with CNF reinforced BPU foam core. Kraft paper was used as a skin and epoxy resin was used as adhesive resin and the composite laminates were prepared using vacuum infusion technique. These nanofiber reinforced core materials resulted in sandwich panels with improved mechanical properties. X-ray tomography showed that the resin did not penetrate into the core but only the foam surface layer. Moreover, the results were evaluated in a material selection process by means of minimizing merit indices. A trend in the behaviour of compressive properties of the foam and flexural properties of the sandwich panels could be established. The addition of small amount of cellulose nanofibers to BPU based foams is leading to a foam which have similar properties as commercial rigid PU foams. © 2017 International Committee on Composite Materials. 

  • 3.
    Frisk, Nikolina
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Sain, Mohini
    University of Toronto.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Novel Applications of Nanocellulose: Lightweight Sandwich Composites for Transportation2015Ingår i: Reference module in materials science and materials engineering / [ed] Saleem Hashmi, Amsterdam: Elsevier, 2015Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    This chapter is focusing on improvement of the mechanical properties of bio-polyurethane (PU) foam by reinforcing the pre-resin with cellulose nanofibers (CNF). The prepared foam performance was evaluated by manufacturing lightweight sandwich panels using vacuum infusion process with CNF-reinforced bio-PU foam core. Cellulose fiber network (kraft paper) was used as a skin and epoxy resin was used as adhesive resin. The sandwich was tested and compared to a non-reinforced PU foam core sandwich in terms of compressive, flexural, and structural properties. The results showed that the CNF-reinforced foam resulted in sandwich panel with improved mechanical properties, and to foam with smaller cell size and lower open cell content. Moreover, the results were evaluated in a material selection process by means of minimizing merit indices. A trend in the behavior of compressive properties of the foam and flexural properties of the sandwich panels could be established. Overall, the results indicated that the mechanical properties of bio-PU foam was improved by reinforcing the pre-resin with small amounts of wet carrot CNF.

    Ultimately, this work shows a positive trend suggesting CNF-reinforced bio-PU foam has a great potential for use in commercialized products or structural components in future constructions.

  • 4.
    Pervaiz, Muhammad
    et al.
    Centre for Biocomposites and Biomaterials Processing, Faculty of Forestry, University of Toronto.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Recycling of Paper Mill Biosolids: A Review on Current Practices and Emerging Biorefinery Initiatives2015Ingår i: CLEAN - Soil, Air, Water, ISSN 1863-0650, E-ISSN 1863-0669, Vol. 43, nr 6, s. 919-926Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    a rapidly urbanizing global society, the issue of solid waste management has become even more challenging in recent times. Manufacturing of paper, an integral part of human civilization, generates a substantial amount of effluent sludge, which invariably needs extra monetary resources to dispose-off in millions of tons annually around the world. Currently, most of the widely practiced disposal options, landfilling and incineration, invariably pose serious environmental risks to immediate neighborhoods as well as to society at large. Recent stricter environmental legislations and general public awareness have been forcing paper producers to follow a sustainable approach in dealing with residual biomass generated at their facilities. At the same time, reducing waste at source and recycling have become an integral part of waste management of some responsible companies and governments of the industrialized world have also taken a number of initiatives in this regard. This review presents a holistic overview on current practices in dealing with paper sludge and their environmental and economic implications. Also presented is a comprehensive discussion on emerging biorefinery trends leading to value-added utilization of primary, secondary and mixed biosolids originating from effluent treatments plants, especially from paper mill operations.

  • 5.
    Ranganathan, Nalini
    et al.
    Faculty of Forestry, University of Toronto.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Nayak, Sanjay K
    Central Institute of Plastics Engineering and Technology, (CIPET) Guindy Chennai.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Effect of long fiber thermoplastic extrusion process on fiber dispersion and mechanical properties of viscose fiber/polypropylene composites2016Ingår i: Polymers for Advanced Technologies, ISSN 1042-7147, E-ISSN 1099-1581, Vol. 27, nr 5, s. 685-692Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Viscose fiber reinforced polypropylene (PP/VF) composites were manufactured using long fiber thermoplastic (LFT) extrusion techniques with two different methods namely LFT-l and LFT-2. The compatibilizer [maleated polypropylene (MAPP)] and dispersing agent [stearic acid (SA)] were added to the PP/VF in order to improve the fiber dispersion and interfacial adhesion. The PP/VF composites manufactured using LFT-2 showed better fiber dispersion with higher tensile and flexural properties compared to the composites manufactured using LFT-1 method. Similarly, the impact strength and toughness of the LET-2 composites showed an improvement of 36 and 20% than LFT-1 whereas the average fiber length of composites was decreased from 6.9mm to 4.4mm because of the increase in shear energy as a result of residence time. Further, the addition of SA and MAPP to LFT-2 process has significantly improved the fiber dispersion and mechanical performance. The fiber dispersion and fracture behavior of the LFT-1 and LFT-2 composites were studied using scanning electron microscopy analysis. The Fourier transformation infrared spectra were also studied to ascertain the existence of type of interfacial bonds

  • 6.
    Ranganathan, Nalini
    et al.
    Faculty of Forestry, University of Toronto.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Nayak, Sanjay K.
    Central Institute of Plastics Engineering & Technology, TVK Industrial Estate, Guindy.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Impact toughness, viscoelastic behavior, and morphology of polypropylene–jute–viscose hybrid composites2016Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, nr 7, artikel-id 42981Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this investigation, we studied the impact toughness and viscoelastic behavior of polypropylene (PP)–jute composites. In this study, we used viscose fiber as an impact modifier and maleated PP as a compatibilizer. The toughness of the composites was studied with conventional Charpy and instrumental falling-weight impact tests. The composites' viscoelastic properties were studied with dynamic mechanical analysis. The results show that the incorporation of viscose fibers improved the impact strength and toughness to 134 and 65% compared to those of the PP–jute composites. The tan δ peak amplitude also increased with the addition of the impact modifier and indicated a greater degree of molecular mobility. The thermal stability of the composites was evaluated with thermogravimetric analysis. The addition of 2 wt % maleated polypropylene (MAPP) to the impact-modified composite improved the impact strength and toughness to 144 and 93%, respectively. The fiber–matrix morphology of the fracture surface and the Fourier transform infrared spectra were also studied to ascertain the existence of the type of interfacial bonds. Microstructural analysis showed the retention of viscose fibers in the composites compared to the more separated jute fibers

  • 7.
    Ranganathan, Nalini
    et al.
    Faculty of Forestry, University of Toronto.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Nayak, Sanjay K
    Central Institute of Plastics Engineering & Technology, (CIPET), Guindy.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Structure property relation of hybrid biocomposites based on jute, viscose and polypropylene: The effect of the fibre content and the length on the fracture toughness and the fatigue properties2016Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 83, s. 169-175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present study, the extent of jute and viscose fibre breakage during the extrusion process on the fracture toughness and the fatigue properties was investigated. The composite materials were manufactured using direct long fibre thermoplastic (D-LFT) extrusion, followed by compression moulding. The fracture toughness (KIC) and the fracture energy (GIC) of the PP-J30 composites were significantly improved (133% and 514%, respectively) with the addition of 10 wt% viscose fibres, indicating hindered crack propagation. The addition of viscose fibres resulted in three times higher fatigue life compared with that of the unmodified jute composites. Further, with the addition of (2 wt%) MAPP, the PP-J30-V10 resulted in a higher average viscose fibre length of 8.1 mm, and the fracture toughness and fracture energy increased from 9.1 to 10.0 MPa.m1/2 and 28.9 to 31.2kJ/m2, respectively. Similarly, the fatigue life increased 51% compared with the PP-J30-V10, thus demonstrating the increased work energy due to hindrance of the propagation of cracks.

  • 8.
    Sethi, Jatin
    et al.
    Fibre and Particle Engineering Research Unit, University of Oulu.
    Farooq, Muhammad
    Fibre and Particle Engineering Research Unit, University of Oulu.
    Sain, Sunanda
    Fibre and Particle Engineering Research Unit, University of Oulu.
    Sain, Mohini M.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Centre for Biocomposites and Biomaterials Processing, University of Toronto.
    Sirviö, Juha Antti
    Fibre and Particle Engineering Research Unit, University of Oulu.
    Illikainen, Mirja
    Fibre and Particle Engineering Research Unit, University of Oulu.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap. Fibre and Particle Engineering Research Unit, University of Oulu.
    Water resistant nanopapers prepared by lactic acid modified cellulose nanofibers2018Ingår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, nr 1, s. 259-268Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current work reports a novel, completely water based approach to prepare the water resistant modified cellulose nanopapers. Lactic acid in aqueous medium was attached on cellulose nanofibers surface with the aid of ultra-sonication and later oligomerized (polymerized) by compression molding under high temperature and pressure, to obtain the modified nanopapers with enhanced mechanical properties. The modified nanopapers showed an increase of 32% in the elastic modulus and 30% in the yield strength over reference nanopapers. Additionally, the modified nanopaper was hydrophobic in nature and had superior storage modulus under moist conditions. The storage modulus of wet modified nanopaper was three times (2.4 GPa) compared to the reference nanopapers (0.8 GPa) after 1 h immersion in water. Finally, the thermal stability of the modified nanopaper was also higher than reference nanopaper. The material reported is 100% bio-based

  • 9.
    Sethi, Jatin
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Illikainen, Mirja
    Fiber and Particle engineering, University of Oulu.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Polylactic acid/polyurethane blend reinforced with cellulose nanocrystals with semi-interpenetrating polymer network (S-IPN) structure2017Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 86, s. 188-199Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of the current work was to prepare and characterize a cellulose nanocrystal reinforced semi-interpenetrated network (SIPN) derived from polylactic acid (PLA) and polyurethane (PU) polymers. SIPN films were prepared using solvent casting from 1,4-dioxane solution. The morphology, mechanical and thermal properties of the neat SIPN and its nanocomposite were characterized. A novel dispersion method was used, for the first time, to disperse the CNCs into the polyol. This method led to well dispersed CNCs in the SIPN, and at 1 wt% CNC concentration, the elastic modulus of the nanocomposite was improved by 54% over an unreinforced SIPN. Additionally, the results indicated that the toughness of PLA, which is the main polymer phase, was improved. However, in the nanocomposite, CNCs formed a strong network and reinforced the PU phase, which resulted in a lower toughness of the final material. The storage modulus of the SIPN nanocomposite was higher than that of the neat PLA at temperatures higher than 55 °C up to 100 °C. This increase in thermomechanical properties indicates that the reinforced PU network in the PLA matrix can enhance the thermal behavior of material.

  • 10.
    Sethi, Jatin
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Illikainen, Mirja
    University of Oulu.
    Sain, Mohini
    University of Toronto.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Semi-interpenetrating network derived from polylactic acid/polyurethane blend and reinforced with celulose nanocrystals2016Ingår i: ECCM 2016: Proceeding of  the 17th European conference on composite materials, European Conference on Composite Materials , 2016, s. 539-546Konferensbidrag (Refereegranskat)
    Abstract [en]

    The current work aims to prepare and characterize bionanocomposites based on cellulose nanocrystals and semi interpenetrating networks prepared from PLA and PU. Nanocrystals were dispersed in PU phase with an innovative, novel method called as co-solvent assisted surfactant-less method. The characterization of the materials was done by tensile testing, differential scanning calorimetry and thermogravimetric analysis. The results were progressive and supported the premise that SIPNs are a viable option to prepare mechanically enhanced hybrid matrix that can impart improved mechanical properties to nanocomposites. Additionally, the dispersion method produced excellent dispersion of nanocrystals in the polyol phase, which was successfully transferred to the nanocomposite

  • 11.
    Zhou, Xiaojian
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Sethi, Jatin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Geng, Shiyu
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Berglund, Linn
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Frisk, Nikolina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Aitomäki, Yvonne
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Sain, Mohini
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Oksman, Kristiina
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Dispersion and reinforcing effect of carrot nanofibers on biopolyurethane foams2016Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 110, s. 526-531Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, carrot nanofibers (CNF) were used to enhance the performance of biobased castor oil polyol polyurethane nanocomposite foams. A method of dispersing CNF in the polyol was developed and the foam characteristics and CNF reinforcing effect were studied. Co-solvent-assisted mixing resulted in well-dispersed CNF in the polyol, and foams with 0.25, 0.5 and 1 phr CNF content were prepared. The reinforced nanocomposite foams displayed a narrow cell size distribution and the compressive strength and modulus were significantly elevated and the best compressive strength and modulus were reached with 0.5 phr CNF. Similarly, the modulus of the solid material was also significantly increased based on theoretical calculations. When comparing the foam performance, compressive strength and stiffness as a function of the density, the nanocomposite foams performs as commercial rigid PU foam with a closed cell structure. These results are very promising and we believe that these foams are excellent core materials for lightweight sandwich composites.

1 - 11 av 11
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