Preparation and characterization of foamed wheat straw fiber/polypropylene composites based on modified nano-TiO2 particles

The nano-TiO2 modified foamed wheat straw fiber/polypropylene (F-WSFs/PP) hierarchical composites were fabricated by a hot-extrusion process. To improve the dispersion of nano-TiO2 and increase the compatibility between WSFs and PP, the WSFs were immersed in 1–5 wt% unmodified and coupling agents (A171 or KH550)-modified nano-TiO2 suspensions by vacuum pressure. The size, crystallinity and composition of modified nano-TiO2 were analyzed by Laser particle size analyzer (LS), XRD and FT-IR. Moreover, the modification mechanism was clarified to understand interface interaction between WSFs and PP. SEM results showed that nano-TiO2 was deposited on the WSFs surfaces. UV–Vis showed that WSFs treated with modified-TiO2 exhibited excellent UV-shielding properties in the range of 100–200 nm. Mechanical testing indicated that WSFs treated with 4% KH550-modified nano-TiO2 exhibited the highest flexural (29.27 MPa), tensile (14.38 MPa), and impact (4.55 kJ/m2) strengths. Overall, the TiO2-KH550 modified F-WSFs/PP composites excellent UV-shielding properties and mechanical strengths.