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High-density polyethylene (HDPE), bagasse fibers treated by four pulping processes (AS-AQ (alkaline sulfite anthraquinone), SODA-AQ (soda anthraquinone), MEA (monoethanolamine) and chemical–mechanical pulping (CMP)), three levels of nano-SiO2(0, 2, and 5 wt%), and maleic anhydride polyethylene as coupling agent were used to produce pulp–plastic composites (PPCs) by injection molding. The physical and mechanical properties of corresponding composites were evaluated according to ASTM standards. The results showed that compared to untreated bagasse/HDPE composite, the addition of bagasse pulp fibers increased significantly the mechanical properties such as tensile strength and modulus, flexural strength and modulus, and hardness. The chemical pulps-reinforced composites showed better mechanical strengths than that of CMP-reinforced composites, but in some properties, CMP pulp composites have comparable results to the chemical pulp-reinforced composites. Natural fibers (untreated and treated) increased water absorption and thickness swelling of composites compared to pure HDPE. The addition of nano-SiO2particles showed both increasing and decreasing trends on physical and mechanical properties ofPPCs. [ABSTRACT FROM PUBLISHER]

The effect of nanosilica particles on the water resistance of a polyurethane/nanosilica composite coated paper substrate was investigated. The polyurethane/nanosilica composite coating was prepared by dispersing nanosilica powder into solvent-based polyurethane using high mechanical stirring force. Paper substrate was coated with polyurethane/nanosilica composite using a Rod Mayer technique. Various compositions of polyurethane/nanosilica composite coatings on paper substrate were prepared. The total thickness of the paper coated with polyurethane/nanosilica composite was 0·3 mm. The field emission scanning electron microscopy images indicated that the presence of nanosilica has improved the surface roughness and porosity of paper substrate. The addition of nanosilica in polyurethane coating had increased the water resistance ability of the coated paper. It was demonstrated that polyurethane/nanosilica-6% shows better water resistance and exhibits better thermal stability than the nanocomposites with lower nanosilica loading. Fourier transform infrared spectroscopy result shows that there was no chemical reaction between nanosilica and polyurethane. [ABSTRACT FROM AUTHOR]

This paper presents a thorough study on the prediction of the elastic-material constants ratios of blended short-fiber yarns, based on the theory developed by the author for yarns of a single fiber type by considering the structures as transversely isotropic and combined with the techniques used in dealing with hybrid composite materials. The mean tensile strengths of the blended staple-fiber yarns are also predicted, with the exclusion of the statistical and hybrid effects, which will be dealt with in a separate paper because of their extreme complexity. The so-called minimum blend ratio, below which the mean yarn strength will not follow the rule of mixtures, and the critical blend ratio, below which the mean yarn strength will be weakened rather than strengthened owing to the addition of the reinforcing fibers, are calculated, and the variables involved are discussed. Finally, the effects of the breaking strains between the blending-fiber types on the yarn properties are investigated. All results are schematically illustrated and the necessary parametric studies are provided. [ABSTRACT FROM AUTHOR]