| Polylactic acid (PLA) is a highly versatile, biodegradable, aliphatic polyester derived from 100% renewable resources, such as corn and sugar beets. PLA offers great promise in a wide range of commodity applications. Although PLA has such advantages, it has some inherent drawbacks that can not be neglected: its brittleness, thermal instability and difficulty in film extrusion have prevented it from packaging and some other applications. Those shortcomings have prevented this popular material from further usage into our daily lives. In this thesis, we introduced amide segments into the PLA chain in order to strengthen the inner forces between molecular chains.A novel polyesteramide (PEA), poly(lactic acid-co-β-Alanine), was synthesized by direct melting copolymerization, and characterized by FT-IR, NMR, GPC and DSC. We found that the optimized polymerization conditions should be at 180℃for 15 h under vacuum. FT-IR results indicate that hydrogen bonds were successfully introduced into the polymer chain, and the highest molecular weight the products could reach decreased drastically when the molar ratio ofβ-Alanine segments increased in PEA chain. The thermo analysis also indicates that the introduction ofβ-Alanine accelerates the decrystallization as well as the degradation process of the PEA.We also used solution copolymerization to synthesis PEA with PLA andβ-Alanine. We could get products with higher molecular weight, but in longer reaction time.At last, we investigated a particular usage of this copolymer: A compatibilizer in the PLA/ alcoholysis nylon blends. The Preliminary results showed it could improve component's compatibility as well as the mechanical properties of the blend films. |
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