| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 98 === Biodegradable polymers have recently attracted great attension because environmental pollution. PLA is a aliphatic thermoplastic polyester and a biodegradation plastic. In this study, we use hydrophobic intercalation agent (POP-diamine) to ezpansion the inter-lamellar space of Na+-MMT. We hope it could increase the disperse of montmorillonite. Then we measure the physical properties and mechanical properties, and compare with commercial modified montmorillonite (C30B).Finally, we degrade the PLA nanocomposites by streptomyces 76T-1 to investigate the degradability of PLA nanocomposites. We could expand the inter-lamellar space from 1.24 nm to 4.64 nm by using POP-diamine as intercalation agent. But after meting blending, the inter-lamellar space would reduce to 2.26 nm. The reason is the POP-diamine would move to PLA matrix after melting blending. We could prepare intercalation-nanocomposite by melting blending with C30B. When adding C30B, we could increase the modulus of PLA.And when adding the POP-MMT, we could increase the elonation at break. By adding the montmorillonite, we could increase the thermal ability of PLA. We use Streptomyces sp. 76T-1 to degrade PLA. After degradating test in 72 hour, PLA could be degradating completely. Adding cloisite 30B could accelerate the degradating rate. But POP-diamine could slow down the degradating rate. After degradating test in 72 hour, we still have 40%wt PLA. After degradating test, we found that the crystallinity and molecular weight have not changing. For understanding the relation between degradation rate and crstallinity, we made hight crystallinity PLA (crystalinity 37 %). After degradating test in 72 hour, we still have 80 wt% PLA. In the result of SEM, we found that Streptomyces sp. 76T-1 degrade the amorphous firstly, then crystalline. By the results of thickness test and molecular weight test in this paper, we assume that Streptomyces sp. 76T-1 degrade PLA by surface erosion.
|
|---|
