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本文通过有氧生物降解方法和计算机模拟方法对淀粉颗粒度p高于和低于渗透临界值pc时,聚乙烯-淀粉(PE-S)共混物的生物降解动力学进行了研究。在计算机模拟中应用到两个淀粉的降解模型(i)微生物侵入共混物的过程(ii)大分子物质(梅等)扩散到共混物内部导致小分子物质向表面反扩散,小分子物质进一步被微生物同化的过程。微生物的侵入模型以扫描电子显微镜对PE-S共混物的实验研究结果为基础,该共混物中含有1~15微米的淀粉颗粒。根据土壤掩埋实验的测试结果,在聚乙烯基质的淀粉颗粒位置上,有明显的微生物生长现象。酶的扩散基于PE-S共混物的水解实验。在堆肥实验后的水解实验中发现了小分子物质的产生。通过计算机模拟了在共混物中单分散及多分散的淀粉颗粒与微生物及酶的接触过程。需氧生物降解的二氧化碳产生量反映了共混物中淀粉的微生物侵入能力。淀粉的降解度A与时间t遵循幂函数关系Atn,其中指数n取决于微生物可接触到淀粉簇的分数维度和通道大小,并且在淀粉的颗粒度p大于临界渗透尺度Pc时该值接近于1。微生物侵入的模拟表明,当淀粉颗粒度接近pc时,平均指数n的值约为0.5;当淀粉颗粒度p>pc时约为0.25,在p>pc时约为0.5。有氧堆肥生物降解的实测指数表明无论淀粉尺寸大于或小于临界尺寸,微生物的侵入是主要?
In this paper, the biodegradation kinetics of polyethylene-starch (PE-S) blends were studied by means of aerobic biodegradation and computer simulation methods when the starch particle size p was above and below the critical value pc. Degradation Models of Two Starch Applied in Computer Simulation (i) Microbial Intrusion into Blends (ii) The diffusion of macromolecular species (plum, etc.) into the blend results in the counter-diffusion of small molecules to the surface, The process of further assimilation by microorganisms. The invader model of the microorganisms is based on the experimental investigation of the PE-S blend by scanning electron microscopy, which contains 1 to 15 micron starch granules. According to the test results of soil burial experiment, there is obvious phenomenon of microbial growth on the starch granules of polyethylene matrix. Enzyme diffusion was based on hydrolysis experiments of PE-S blends. The production of small molecules was found in hydrolysis experiments after compost experiments. The contact process of monodisperse and polydisperse starch granules with microorganisms and enzymes in the blends was simulated by computer. The amount of carbon dioxide produced by aerobic biodegradation reflects the microbial intrusion ability of the starch in the blend. The starch degradation A and time t follow the power function Atn, where the index n is dependent on the fractional dimension and channel size of the microorganisms accessible to starch clusters and is close to 1 when the starch particle size p is greater than the critical osmotic scale Pc . Simulations of microbial invasion show that when the starch particle size is near pc, the average index n is about 0.5; when the starch particle size is> pp, it is about 0.25; at p> pc, it is about 0.5. The measured indices of aerobic composting biodegradation show that microbial intrusion is predominant whether starch size is larger or smaller than the critical size.