Study On The Preparation And Properties Of The Acetylation Rice-straw-biogas Residue/PVC Composites

Rice straw has abundant yields but low utilization rate,and integrating rice straw with plastic polymers to produce composites is a kind of new way to enhance the utilization rate of rice straw.In the article,the methods of anaerobic process and acetylation was simultaneously exploited to modify rice straw,and rice straw/polyvinyl chloride(PVC)composites was prepared.The structure and properties of the modified rice straw and its composites were researched,and conclusions are as follows:At first,rice straw was processed by anaerobic fermentation for 30 days.With the time extending,rice straw fiber's structure was destructed,and its surface became crude.The crystallinity(CrI)of rice straw decreased by 4%when rice straw was digested in 30 days.Meanwhile,the infrared absorption peak of hydroxy gradually weakened from 10 days to 30 days,'indicating the polar of rice straw declined.In addition,with the unstable biomass in the rice straw degraded and lignin accumulated after 30 days'fermentation,the initial decomposed temperature of rice straw increased by 40 ?.Rice-straw-biogas residue(BR)after 30 days' fermentation reacted with acetic anhydride,and the optimum conditions of acetylation were researched by orthogonal experiment of L9(34).The optimum conditions of acetylation were that 140?,4 h,10 mL acetic anhydride/g BR,and 0.08 g catalyst/g BR.In contrast with the untreated rice straw(RS)and rice straw biogas residue(BR),the acetylated biogas residue(ABR)hadn't appeared the infrared absorption peak of-OH,but a strong absorption peak of C=O broke out,which claimed that acetic anhydride had been efficiently linked to BR.At the same time,a layer of esterification film came into being in the surface of ABR,and it amended some structure flaws in BR.The cellulose crystallinity of ABR decreased by 47.4%in comparison with of RS.Moreover,the decomposed initial temperature of ABR was 30? higher than BR,and ABR got better thermal stability.In contrast with RS/PVC,BR/PVC and ABR/PVC have better hydrophobicity and thermal property,but glass transition temperature of ABR/PVC slightly rose,which don't facilitate the manufacture of composites.ABR/PVC has better tensile and flexible properties than RS/PVC,and tensile strength and flexible strength increased by 29.4%and 25.5%respectively.However,BR/PVC and ABR/PVC have lower elongation than RS/PVC.The addition ratio of ABR affects the rheological and mechanical properties of composites.The proportion of ABR from 10%to 30%can help to reduce the viscosity of the composites and improve its rheological properties.The mechanical properties test showed that the tensile strength and elongation at break of ABR/PVC composites decreased with the increase of ABR addition ratio,and the flexural strength of composites with 30%ABR content is the biggest,which increased 2.1MPa compared with flexural strength of pure PVC.Summing up above conclusions,it is effective to improve the physical and chemical properties of rice straw processed by anaerobic fermentation and acetylation,and heighten the compatibility with rice straw and PVC,strengthen the mechanical properties of composites,contribute to the material utilization of rice straw.