Development of New Biodegradable Composite Materials from Cellulose (or Wood) and Starch

证实了醋酸纤维素(CA)和乙酰化木材分别通过二元酸酐/单环氧化合物捏合过程在其游离羟基处生成寡酯(OE)链，从而有效地增塑。研究还发现，CA具有足够的增塑性，可以与马来酸甲酯或十二烯基丁二酸酐混炼。在这种情况下，加入己内酯使增塑材料的加工性能大大提高。这些反应受CA的取代度、反应性增塑剂的种类、增塑剂与CA的比例以及捏合时间等因素的影响。另一方面，在使用前几种增塑剂的情况下，材料中存在增塑剂之间反应生成的未反应单体和齐聚物。它们对CA起到了很好的外部增塑剂的作用，然而，其中一些却流到了床单上。可见，OE接枝链的数量和长度对控制外增塑剂的渗漏是有效的。此外，即使在接枝程度不足的情况下，加入甲基丙烯酸酯作为固色剂，在适当的增塑剂种类和工艺条件下也能有效地控制渗漏。对增塑后的样品进行生物降解试验，发现增塑剂相对分子质量越小、为脂肪族化合物、淀粉所占比例越大，样品的生物降解速度越快。以聚丙烯和高密度聚乙烯作为不可生物降解的对照样品，以取代度为1.7的CA作为塑化样品的基质聚合物。结果表明，所有塑化样品均发生降解，失重逐渐增加，在2年内消失，而对照样品则完全不降解。

It was confirmed that cellulose acetate (CA) and acetylated wood wereeffectively plasticized respectively by kneading process with dibasic acid anhydride/monoepoxide to produce oligoester (OE) chains at their free hydroxyl groups. And it was also found that CA was plasticized enough to be kneaded with maleic methyl oleate or dodecenylsuccinic anhydride. In this case, addition of epsilon-caprolactone made the processability of the plasticized materials much higher. These reactions were affected by the degrees of substitution of CA,the kinds of reactive plasticizers, the proportions of plasticizers to CA,and kneading time, etc. On the other hand, in the case of using the former plasticizers, it was known that the unreacted monomers and oligomers produced by plasticizers reaction among themselves existed in the materials. They worked as good external plasticizers for CA,however, some of them bled over sheets. It became clear that the amount and length of OE graft chain was effective in controlling external plasticizers bleeding. Moreover, even in the case of insufficient grafing level, addition of methacrylates as the fixing agent was effective to control bleeding when suitable kinds of plasticizers and processing conditions were used. As the results of biodegradation tests for plasticized samples, it was found that the biodegradation rate of the samples became faster when plasticizers have smaller molecular weight, they are aliphatic compounds, and the proportion of starch was higher. In these tests, polypropylene and high density polyethylene were used as non-biodegradable control samples, and CA with degree of substitution 1.7 was used as the matrix polymer of plasticized samples. It was revealed that all the plasticized samples degraded and their weight losses progressed gradually according to the tendency mentioned above, to disappear within 2 years, though the control samples didn't degrade at all.