Development of Novel Biodegradable Composite Materials from Biomass

研究发现，以己内酯(EPSilon-CL)/乳酸(LA)或乙醇酸(GA)/LA为接枝共单体，可以有效地增塑二醋酸纤维素(CDA)。CDA的塑化程度受接枝链中共聚单体顺序的影响，而这是由epsilon-CL的反应性大于La.接枝侧链上引入的epsilon-CL越多，接枝CA的弹性越大所控制的.当GA/LA共聚单体接枝时，接枝侧链的数量随着GA/LA比例的增加而增加，从而改善了产品的物理性能。从差示扫描量热仪的测试结果可以看出，随着GA/LA比例的增加，CDA的玻璃化转变温度向低温移动，即CDA的热塑化程度增加。在另一项实验中，这些接枝的CDA成功地与可生物降解的聚碳酸酯共混，得到了具有高力学性能的可生物降解的复合材料，取得了令人满意的结果。为了验证产物的生物降解性，采用了合成试验。通过测试发现，产品的质量下降了60%以上，产品的相对分子质量也有较大的下降。从组成材料的分析可以看出，在降解处理过程中，不仅发生了接枝侧链的断裂，而且还发生了CDA的乙酰基断裂。对玉米淀粉的热塑性进行了研究。在这种情况下，淀粉首先以乙酸乙烯酯为乙酰化剂进行酯交换反应，然后与EPSilon-CL和L-丙交酯进行开环接枝共聚。得到的接枝乙酰化淀粉在保持高相对分子质量的同时表现出较好的热塑性。

It has been found that cellulose diacetate (CDA) was effectively plasticized by using epsilon-caprolactone (epsilon-CL)/lactic acid (LA) or glycolic acid (GA)/LA as graft-co-monomers. The degree of plasticization of CDA was influenced by the sequence of co-monomers within the graft chain, which was controlled by the fact that reactivity of epsilon-CL was greater than that of LA.The more epsilon-CL was introduced in graft side chains, the more elastic the grafted CA became. When GA/LA co-monomers were grafted, the amount of grafting side chains increased with increasing in the ratio of GA to LA, and consequently the physical properties of the products were improved. From the results of measurement with differential scanning calorimetry, it was made clear that glass transition temperature due to CDA shifted to lower temperature, that is, increase in the thermoplasticization of CDA, with increasing in the ratio of GA to LA.In the other trial, these grafted CDAs, were successfully blended with biodegradable polycarbonate, resulting biodegradable composites with high mechanical properties, being biodegradable, was tried to get satisfactory results. In order to confirm the biodegradability of the products, composing test was adopted. By this testing, weight decrease of more than 60% and large decrease of the products' molecular weight were found. From the analysis of the composed materials, it became apparent that there occurred not only the scission of grafted side chain but also that of acetyl group from CDA during the degradation treatment. Thermoplasticization of corn starch was also attempted. In this case, starch was first acetylated by transesterification using vinyl acetate as the acetylating agent, followed by the ring opening graft-co-polymerization with epsilon-CL and L-lactide. The obtained grafted acetylated starch revealed preferable thermoplasticity with retaining the high molecular weight.