【作者】 卢发燕；

【导师】 梁兴泉；

【作者基本信息】 广西大学 ， 有机化学， 2007， 硕士

【摘要】 本文将淀粉及自由基捕捉剂添加到聚乙烯中，分别在375W紫外灯的照射和模拟堆肥的条件下，考察了随着光照时间和堆肥时间的增加，聚乙烯及自由基捕捉剂的变化情况，同时对比了以三种多羟基化合物(淀粉、山梨醇醚、甘油醚)为降解促进剂，二苯胺为自由基捕捉剂，在模拟堆肥条件下对聚乙烯降解的加速过程。利用薄层色谱分离得到自由基捕捉剂捕获的部分链反应中间产物，并通过紫外光谱、红外光谱和质谱等对捕获的中间产物进行了分析和测试。主要实验结果如下：1、在光照和多羟基化合物存在的条件下，聚乙烯在没有引发剂存在的情况下发生了光降解。从降解样品中提取的小分子物质中发现有羧酸类物质生成；同时发现有小分子N-烷基取代二苯胺生成。小分子N-烷基取代二苯胺的生成说明在实验条件下含多羟基化合物的聚乙烯样品以自由基的方式发生了降解，而且降解过程中有小分子烷基自由基产生。由于在未添加多羟基化合物的聚乙烯样品中没有发现相同的结果，因而被认为是多羟基化合物对聚乙烯所产生的诱导光降解作用的证据。2、在堆肥条件下，多羟基醚的存在能加速聚乙烯的降解。在聚乙烯链反应所产生的碎片中带有羟基，说明多羟基醚碎片可能与聚乙烯链反应的碎片产生了重排。实验表明这种降解是以自由基的方式进行的，其中氧气起到了重要的作用。其作用机理可能为：在多羟基化合物／聚乙烯体系中，添加物起到增大表面积的作用，使得氧气能更顺利地进入体系内部，发生氧化反应。此外也有可能是在堆肥条件下，多羟基化合物发生了断链，从而引发一系列的反应，使得聚乙烯发生降解。更多还原

【Abstract】 In this paper the degradation mechanism of the low-density polyethylene(LDPE) as a film was studied with the diphenyamine (DPA) antioxidant as a freeradical catcher. Taking the N- butyl diphenylamine as the flame of reference, thestructural changes of the DPA was investigated by Thin Layer Chromatograph(TLC) and Ultra-violet spectrograph (UV). The degradation products of LDPEwere identified by the Infrared spectrum (IR). Some results have been foundwhen polyethylene was under irradiated by UV light of 375W and undersimulating composting temperature.1、The results showed that under UV light of 375W condition, the LDPE hasdegenerated without any initiator but the starch. Carboxylic acid and the N-alkyl diphenylamine were founded in the degradation products. It showed thatthe degradation mechanism of the low-density polyethylene is a free radicalmechanism. Some small fragments of the alkyl free radical were produced in thedegradation process. It is remarkable that the same phenomenon did not found inthe pure PE sample. So it was considered as the induction of starch effect on thepolyethylene photo-degradation.2、The results showed that multi-hydroxyl ethers have obvious promoted thedegradation of LDPE under simulating composting temperature. It is indicatedthat the degradation can be explained with a free radical mechanism. The oxygen in environment has great influence to the degradation. The results ofFTIR showed that the compounds containing carbonyl, hydroxide groups are theultimate degradation products of the hydroperoxides and other dominantmedium products. The rusults of DSC showed that the degree of crystaUinityincreases with the composting time. Some small fragments of the alkyl freeradical were produced in composting process.更多还原