茶粉/聚乳酸复合材料的增韧改性

Toughening of tea dust/poly(lactic acid) composites

为高值化利用茶产业剩余物资源,以茶粉(TD)为生物质填料,聚乳酸(PLA)为基体,以甘油(GL)、聚乙二醇400(PEG400)、环氧大豆油(ESO)和乙酰柠檬酸丁酯(ATBC)为增塑剂,制备了可降解TD/PLA增韧复合材料,并采用红外吸收光谱、热重分析、转矩流变仪、扫描电镜及力学性能测试等考察了增塑剂对TD/PLA复合材料结构与性能的影响。结果表明:4种增塑剂都可改善TD/PLA复合材料的加工流变性,GL的添加不利于复合材料韧性,PEG、ATBC及ESO的添加提高了复合材料韧性,其中ESO增韧效果最佳,其添加制备的复合材料断裂伸长率及缺口冲击强度分别提高了154.23%和65.53%,GL增韧效果最差,ATBC增韧后复合材料力学强度和模量最高。FTIR分析表明,ATBC和ESO可与PLA发生一定相互作用,使C—O键红外吸收峰位增大,其增韧后复合材料吸水率下降。ESO添加提高了TD/PLA复合材料的维卡软化点和热稳定性。SEM图片显示,TD/PLA/ESO复合材料断面粗糙,ESO分散较均匀,与PLA部分相容,而TD/PLA/GL复合材料断面出现严重相分离结构。该研究结果可为进一步探索聚乳酸基茶塑复合材料制备及应用提供试验数据和理论参考。

In order to make high-valued use of the tea waste,we prepared the toughened tea dust/poly（lactic acid）（TD/PLA）composites with a melt blending method,and using glycerol（GL）,polyethylene glycol,epoxidized soybean oil（ESO）and tributyl acetylcitrate（ATBC）as plasticizers to improve the ductility of TD/PLA Fourier infrared absorption spectroscopy（FTIR）,thermogravimetric analysis（TGA）,torque rheometer（TR）,scanning electronic microscopy（SEM）and mechanical test were adopted to study the effects of plasticizers on the structure and performance of TD/PLA blends. The results showed that the addition of GL,PEG,ESO or ATBC resulted in an improvement in the processing rheological properties and toughness,but a decrease in mechanical strength. The TD/PLAcomposites showed best toughness by adding ESO and the corresponding elongation at break and notched impact strength increased by 154.23% and 65.53%,respectively. The TD/PLA composites showed the best mechanical strength with ATBC and the worst ductility plasticized with GL. The interaction between ESO or ATBC and PLA was confirmed by a small shift of C—O stretching peak in the IR spectrum. The water adsorption of the composites decreased with the addition of ESO or ATBC but increased with PEG or GL. The vicat softening point and thermal stability of the TD/PLA composites were improved in the presence of ESO. The fracture surface SEM images of the composites indicated that ESO was well dispersed in PLA matrix and the fracture surface morphology was much rough,while there was distinct phase separation in the fracture surface of TD/PLA/GL composites.