Vigilancia tecnológica

AbstractMicrocellular foamed wood?plastic composites (WPCs) have shown good development prospects in environmentally?friendly composites. Herein, the foamed wood flour (WF)/polypropylene (PP) composites were fabricated by mold?opening injection molding using supercritical N2 as a physical foaming agent. The effects of nano TiO2 on the microcellular structure and mechanical properties of WF/PP composites were investigated, and the results show that nano TiO2 accelerates the crystallization rate and reduces the crystallinity of PP, which is beneficial to the formation of foamed homogeneous systems and cell growth in the WF/PP composites. This is mainly due to heteronucleation effect of nano TiO2, resulting in the refinement of crystal. Molecular chain movement of PP is limited with the introduction of nano TiO2, resulting in increased the melt elasticity of WF/PP composites, thereby reducing cell coalescence and collapse. With the addition of 5 wt% nano TiO2, the cell density was increased by 393.8%, the cell size was reduced by 54.4%, and the cell size homogeneity was clearly improved. In addition, impact strength increased by 33.3%. The improved foamability of WF/PP composites using nano TiO2 shows a great promise for the production and application of WPC foams, especially in automotive, packaging and building areas.