Abstract:

In order to improve the mechanical properties of the PVA film, corn starch was selected as raw materials, ammonium persulfate and urea were used as initiators at 50℃, and acrylamide was added to graft the starch to prepare acrylamide modified corn starch/PVA composite film. Among them, the grafting rate of the modified starch was optimized to determine the best synthesis conditions: the mass ratio of starch/acrylamide was 3∶7, the initiator ammonium persulfate accounted for 0.5% of the total monomer mass, and urea accounted for 0.5% of the total monomer mass. Furthermore, a series of modified corn starch/PVA composite films were prepared using the optimized modified starch as the modifier. Fourier infrared spectroscopy and scanning electron microscope (SEM) were used to characterize the composition and structure of the composite film, and the mechanical properties, water resistance, heat resistance and other physical and chemical properties of the composite film were measured. The results show that the monomer conversion rate of 30%ST-0.50%APSU modified starch is 95.0%, and the grafting rate is 85.2%. The heat resistance of 30%ST-0.50%APSU/PVA composite film is slightly decreased, but the elongation at break is increased by 256%, and the water resistance is increased by 43.1%.

Key words: corn starch, acrylamide, polyvinyl alcohol, modified starch, polyvinyl alcohol (PVA) composite film

摘要：

为了改善聚乙烯醇（PVA）膜的机械性能，选用玉米淀粉为原材料，50℃条件下以过硫酸铵和尿素为引发剂，同时加入丙烯酰胺对淀粉进行接枝改性，制备得到丙烯酰胺改性的玉米淀粉/PVA复合膜。其中，优化改性淀粉的接枝率确定最佳合成条件为淀粉/丙烯酰胺的质量比为3∶7、引发剂过硫酸铵占单体总质量的0.5%、尿素占单体总质量的0.5%。进一步利用优化的改性淀粉为改性剂，制备了系列改性玉米淀粉/PVA复合膜。采用傅里叶红外光谱、扫描电子显微镜（SEM）对复合膜的组成与结构进行表征，同时测定复合膜的机械性能、耐水性、耐热性等物化特性，结果表明30%ST-0.50%APSU改性淀粉的单体转化率为95.0%，接枝率为85.2%。 30%ST-0.50%APSU/PVA复合膜的耐热性能轻微下降，但断裂伸长率提高了256%，耐水性能提高了43.1%。

关键词: 玉米淀粉, 丙烯酰胺, 聚乙烯醇, 改性淀粉, PVA复合膜