Study Of Rice Husk/Polypropylene-Low Density Polyethylene Microcellular Foaming Composites

Because the microcellular foaming composites are not only environmentally friendly and sustainable,but also light in weight and low in density,the study of microcellular foaming wood/plastics composits has drawn more attention recently. In ordter to improve the composites mechanical properties,lower the desity and the cost,rice husk/polypropylene(PP)/low density polyethylene(LDPE) composites were prepared and their mechanical property,thermal property, rheological property and microstructure were studied.In this study,the composites were prepared with polypropylene(PP)low density polyethylene(LDPE)and rice husk flour(under 60 mesh)as well as maleic anhydride-grafted polypropylene(MAH-g-PP)as the compatibilizing agent and azodicarbonamide(AC)as the foaming agent by means of injecting mold. MAH-g-PP was used for improving the interfacial compatibility between PP and rice husk.The mechanical property,thermal property and rheological property of rice husk/PP/LDPE microcellular foaming composites were determined.The experimental results show that with the increase of rice husk flour content,the impact strength and tensile strength of composites decrease significantly,the bending strength increase,the density of composites increase gradually,the Vicat softening point of composites increase significantly and the processing mobility decreases.The results also show that MAH-g-PP can significantly improve the interfacial compatibility between PP and rice husk,and thus to improve their mechanical properties and thermal properties,when the content of MAH-g-PP are 6 shares,the impact strength,tensile strength and density have reached a peak value,when the content of MAH-g-PP are 8 shares,the Vicat softening point has the highest value.With increase of AC content,the impact strength of the composites increases firstly and then decreases,bending strength remains constant, while the tensile strength decreases sharply;density decreases firslyt and then increases.The LDPE can improve the foaming properties of composites.When the riation of PP and LDPE is 70:30,the composites have the best comparative probilities.The microstructure analysis of the composite by SEM and polarizing microscope showes that with the increase of rice husk content,the number of the microcellular cells reduces and the cell distribution uniformity gets worse. MAH-g-PP can improve the interfacial compatibility between PP and rice husk flour,the dispersion of rice husk flour and the foaming properties of the composites.With the increase of AC content,the size of cell increases and more opened cells are observed.LDPE can improve the foaming properties of PP,but an excessive amount of LDPE will hinder the formation of cells.In addition,rice husk flour,MAH-g-PP and LDPE can reduce the grain size and improve the performance of composite materials.