Preparation and properties of wheat straw fiber‐polypropylene composites. I. Investigation of surface treatments on the wheat straw fiber

Effects of alkalization, acetylation, and maleic anhydride grafted polypropylene (MAPP) treatments on the thermal and chemical properties of the wheat straw fiber were investigated using thermogravimetric analysis, infrared spectrophotometer, X‐ray diffraction, and scanning electric microscopy techniques. It was found that the wheat straw fiber was not prone to weight loss at 170°C and the treated wheat straw fiber exhibited more thermal stability than the untreated wheat straw fiber. Alkalization increased relative cellulose content and exhibited more crystalline due to a rearrangement of the crystalline regions. It also prolonged the degradation of the wheat straw fiber at higher temperatures due to the increased crystallinity of cellulose. Compared with alkalization, acetylation had more effect on the thermal and chemical stability in the wheat straw fiber contributing to a formation of ester bonding. MAPP improved the thermal stability partly because of a lower grafted ratio of maleic anhydride. Acetylation and MAPP treatment both decreased the crystallinity of the wheat straw fiber.