Study On Processing And Modification Of Biodegradable Plastics Poly(3-Hydrobutyrate-Co4-Hydroxybutyrate)

In this thesis, Poly (3-hydroxybutyrate-co-4-hydroxybutyrate)[P(3HB-co-4HB)] with5%of4HB molar contents were selected as raw materials. Chain extended modification of P(3HB-co-4HB) was carried out via melting extrusion with IPDI and ADR-4370as chain extenders. Fourier transform infrared spectroscopic(FTIR), differential scanning calorimetry(DSC), polarized optical microscopy(POM), capillary rheometer, Brabender plastics instrument.etc. were used to characterize the effects of various chain extender and their dosage on the structure, molecular weight, melting point, spherulite morphology, mechanical properties, fracture morphology.etc.of P(3HB-co-4HB). The nano-meter montmorillonite (nano-MMT) was treated by surface modification, and the treated nano-MMT was melt and mixed with P(3HB-co-4HB) in the mixer of Brabender plastics instrument to produce the nano-composites. The effect of the dosage of nano-MMT on the composites’ mechanical properties was investigated. We put emphasis on the discussion of the surface modification and combining chain extender and nano-MMT on the composites’ melting point, spherulite morphology and mechanical properties, etc.The results show that (1) IPDI and ADR-4370could be reacted with P(3HB-co-4HB), enhanced the molecular weight. Both single or match use of IPDI and ADR-4370can significantly increase the melt apparent viscosity and improve the processing properties and mechanical properties of P(3HB-co-4HB). According to the DSC、POM analysis of P(3HB-co-4HB) before and after chain-extending, two chain extenders can both effectively improve the compatibility of the two microcrystalline phases and refine the spherulite; The spherulite size and density of the copolyesters can be effectively refined and improved with two chain extenders. In fact. IPDI took an important part in spherulite morphology. The comprehensive properties of P(3HB-co-4HB) achieved the optimum with IPDI at1wt%.(2) P(3HB-co-4HB) and Nano-MMT after pretreatment are partially compatible, the spherulite size was refined significant.Surface modified nano-MMT can reinforce and toughen P(3HB-co-4HB). The Vicat softening temperature was influenced by the nucleating agents in somewhat. But none treatment nano-MMT had little effectivity in mechanical properties of P(3HB-co-4HB).(3) Compared with vavious of modifications (IPDI, ADR-4370and the two matched) on spherulitic morphology, mechanical properties and fracture morphology. When adding single IPDI. the comprehensive properties achieved the optimum. Then single nano-MMT, the last was nano-MMT and IPDI matched.