Studies on the properties of rice-husk-filled-PP composites: effect of maleated PP

Rice husk is a by-product of rice milling process that usually finds inadequate final disposal (burning, land filling). Thermoplastics composites filled with rice husk flour are materials that offer an alternative for using this agricultural resource viewing the production of low dense materials with some specific properties. In this work composites of polypropylene (PP) and rice husk flour (RHF) were prepared by melt extrusion. Maleic anhydride-modified PP (MAPP) was added as a coupling agent. It was verified that tensile strength decreased with filler loading. The presence of MAPP improved this property showing a strong dependence on the MAPP/RHF ratio (MAPP/RHF = 0.03 produced the best results). The density of the composites slightly increased with filler and coupling agent in comparison to pure PP. The presence of MAPP diminished more than 20% water uptake in highly-loaded composites

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