Thermal and mechanical properties of chitosan nanocomposites with cellulose modified in ionic liquids

In this paper, ionic liquid treatment was applied to produce nanometric cellulose particles of two polymorphic forms. A complex characterization of nanofillers including wide-angle X-ray scattering, Fourier transform infrared spectroscopy, and particle size determination was performed. The evaluated ionic liquid treatment was effective in terms of nanocrystalline cellulose production, leaving chemical and supermolecular structure of the materials intact. However, nanocrystalline cellulose II was found to be more prone to ionic liquid hydrolysis leading to formation larger amount of small particles. Each nanocrystalline cellulose was subsequently mixed with a solution of chitosan, so that composite films containing 1, 3, and 5% mass/mass of nanometric filler were obtained. Reference samples of chitosan and chitosan with micrometric celluloses were also solvent casted. Thermal, mechanical, and morphological properties of films were tested and correlated with properties of filler used. The results of both, tensile tests and thermogravimetric analysis showed a significant discrepancy between composites filled with nanocrystalline cellulose I and nanocrystalline cellulose II

Effect of Wood-derived Charcoal Content on Properties of Wood Plastic Composites

The effect of wood-derived charcoal flour on the water resistance and mechanical properties of wood plastic composite (WPC) panels was investigated. The hot press molded WPC panels were produced from polypropylene (37 wt%) with maleic anhydride-grafted polypropylene (MAPP, 3 wt%) and different mixtures of wood flour and charcoal flour. The amount of charcoal flour was gradually increased up to 60 wt%. The thickness swelling and water absorption of WPC panels considerably decreased with increasing charcoal flour content. The internal bond strength and bending properties of the WPC panels significantly improved with increasing charcoal flour content. This was mainly attributed to the high amount of pores and gaps in the charcoal flour. Melted polypropylene could get into the pores and gaps during the hot press molding, which lead to a better interfacial adhesion between polymer matrix and wood filler. The results showed that the charcoal flour could be partially substituted for the wood flour in the production of WPC panels having higher dimensional stability and internal bond strength

Influence of coupling agent in compatibility of post-consumer HDPE in thermoplastic composites reinforced with eucalyptus fiber

This study investigates the feasibility of using recycled high density polyethylene (HDPE) and wood fiber from species Eucalyptus grandis (EU) to manufacture experimental composite panels. The use of maleated polyethylene as coupling agent (CA) improved the compatibility between the fiber and plastic matrix. The mechanical properties of the resultant composites were compared with polymer with and without compatibilizer. The influence of the coupling agent (CA) in the polymer matrices and composites were evaluated at different concentrations, checking the physical, mechanical and thermal properties of wood plastic composites (WPC). Results of mechanical, physical and thermal properties showed that concentration of 3% w/w CA in the polymer matrices was that which showed the best results, but in the composites properties were very similar in all formulations. Based on the findings in this work, it appears that recycled materials can be used to manufacture value-added panels without having any significant adverse influence on material properties

Effect of Alkaline Treatment and Pre-impregnation on Mechanical and Water Absorbtion Properties of Pine Wood Flour Containing Poly (Lactic Acid) Based Green-Composites

The effect of surface treatments and wood flour (WF) ratio on the mechanical, morphological and water absorption properties of poly (lactic acid) (PLA) based green-composites were studied. WF/PLA interfacial adhesion was promoted by means of alkaline treatment and pre-impregnation with dilute solution of matrix material. The composite materials were manufactured with twin screw extruder and injection molded samples were used for characterization. According to tensile test results, the inclusion of WF without any surface treatment caused high reduction at tensile strength in spite of incremental increase of modulus values. As the amount of alkaline treated WF increased, both modulus and tensile strength increased. Both alkaline treatment and pre-impregnation further increased the mechanical properties including tensile strength, tensile modulus and impact strength. Scanning electron microscopy (SEM) micrographs supported these findings. According to dynamic mechanical analysis (DMA) test results, the glass transition temperature of PLA increased with the addition of WF and the highest increment was obtained when pre-impregnated WF was used. Although alkaline treatment had no effect on water up-take properties of composites, pre-impregnation reduced the water uptake of the composite

Comparative study between poly(ethylene-co-vinyl acetate) - EVA expanded composites filled with banana fiber and wood flour

The objective of this study is to develop expanded composites of poly(ethylene-co-vinyl acetate) (EVA) filled with two vegetable reinforcements (banana fiber or wood flour) as well as to evaluate the influence of the type, size and concentration of these reinforcements on the cell growth and their morphological, mechanical, thermal and physical properties. The results indicated that the natural fibers act as nucleating agents and affect the cells stability during the formation of the cellular structure in the expanded composites. The mechanical properties of the expanded composites are directly related to the composite expansion degree. Comparative results of the use of vegetable residues indicate that wood flour reinforcement provides more homogeneous cells, while banana fibers restrict the expandability of the composite and its density