Study On The Preparation And Property Of Poly(lactic Acide)/Poly(butylene 2,5-furan Dicarboxylate) Blends

Poly(lactic acide)(PLA)is a bio-based and biodegradable polymer material derived from renewable resources.It possesses good strength,modulus,biocompatibility and optical properties,and it can be extensively applied in medicine,packing,agriculture and other fields.However,the toughness of PLA is poor,and the elongation at break and notch impact strength of PLA are low,limiting the application of PLA in toughness requirements areas.So far,the toughening agents reported in the literature can not toughen PLA while keeping the high strength and molulus of PLA.In this thesis,we use a bio-based polyester to toughen PLA,and try to keep good strength,modulus and heat resistence of PLA at the same time.2,5-furandicarboxylic acid and 1,4-butanediol were used as main raw material to synthesize poly(butylene 2,5-furan dicarboxylate)(PBF)by using traditional method of esterification and melt polycondensation.Then acquiring the PLA/PBF blends through directly blend with PLA and PBF.The toughness,reflective performance and barrier property of blends are investigated.The major findings are as follows:(1)The influence of PBF on the thermal properties,crystallization behavior,morphology and mechanical properties of PLA were systematically investigated.We analyze the morphology of these blends before and after the stretch.The droplet of PBF phases become fibrillar after stretch,and the length increases 5 to 17 times.With the content of 20% PBF,the elongation at break of blend improved from 7.4% for PLA to 223%.Moreover,the modulus,strength and HDT were barely lower than before.(2)In the scope of the visible spectrum,PLA/PBF blends with different content of PBF were tested by UV-Vis-NIR,the reflection of sample was prepared by 3D print reached up to 60% with 10% PBF.Through polarized optical microscope(POM),the reflection index of PLA and PBF,and the size of PLA spherulites and PBF droplets in blends are key to influence the reflection of blends.Based on the recognition of commercial 3M products and the results of POM,an optical geometrical model for reflection of PLA/PBF blends is proposed.(3)The barrier properties of PBF and PLA/PBF blends on carbon dioxide,oxygen and water were measured.The barrier property of blends increased as the content of PBF increased.With the content of 30% PBF,the oxygen barrier of blends is 7.4 times better than PLA,the carbon dioxide barrier is 6.3 times better than PLA,and the water barrier is 2 times better than PLA.The addition of furan-based PBF has significant effect on barrier property of PLA.In conclusion,PBF toughen PLA while keeping its strength and modulus.In addition,the retroreflection happens in the binary PLA/PBF blends,with reflection ratio as high as commercial products.The gas barrier properties of PLA/PBF blends is much better than those of pure PLA,and the potential application of such blends is encouraging.