Study On The Spinnability And Preparation Of Biodegradable PLA/PBAT/PHBV Blends

In recent years, environment pollution and energy shortage problems have become increasingly serious, academia and industry are looking for recyclable and environment-friendly green materials. Poly(lactic acid)(PLA) is one of the most studied, the largest output and most successful commercial biodegradable material. While Pure PLA exhibit brittleness, high strength and low elongation at break which makes its application areas is restricted. In contrast with PLA,poly(butylenes adipate-co-terephthalate)(PBAT) is a flexibility and excellent elastomer material.Poly(3-hydroxybutyrate-co-hydroxyvalerate)(PHBV) have the advantage of fast degradation.PLA、PBAT、PHBV are very promising biodegradable materials. Widely use of these green materials to replace petroleum-based materals, will significantly reduce our dependence on oil resources, conducive to the sustainable development.In this paper different mass ratio of PLA/PBAT/PHBV blends and the modified PLA/PBAT/PHBV blends with the additive of GMA and DCP were prepared by melting co-extrusion. The crystallization behavior, thermal characteristics, morphology, rheological behavior and mechanical properties of PLA/PBAT/PHBV blends were studied respectively. The miscibility and spinnability of PLA/PBAT/PHBV blends were also analyzed in this paper. The results were shown as follows:1. The initial decomposition temperature of PLA/PBAT/PHBV blends increase by 45℃ as compared with pure PHBV and the enhancement in thermal stability of PLA/PBAT/PHBV is achieved. Tg of the components in the blends system changes little which indicates PLA/PBAT/PHBV composites is a incompatible system. At the same time the cold crystallization of PLA is confined by the incorporation of PBAT and PHBV. SEM photographs show the morphology of PLA/PBAT/PHBV composites present as a “sea-island” distribution and PBAT and PHBV distribute in PLA evenly as disperse phases. There are clear interfaces between different phases. When the mass ratio of PBAT increase, the rheological of PLA/PBAT/PHBV blends melt is improve and the effect of temperature on viscosity is increase. Moreover, the stress of PLA/PBAT/PHBV composites is 60% pure PLA while the strain of PLA/PBAT/PHBVcomposites is 2.6 times of pure PLA, toughness of PLA/PBAT/PHBV blends has been improved significantly.2. Tg of the PLA component in PLA/PBAT/PHBV reactive blends decrease with the additive of GMA. Interfaces between different phases become blurred and the morphology shift from completely separated to partially-bonded, even the “island” overall coated by the “sea”.Particle size decreases and its dispersion evenness improved. All these phenomena indicate the compatibilization effect of GMA to PLA/PBAT/PHBV blends is significant. Moreover crystallization of PLA component in PLA/PBAT/PHBV blends has a little change, including the decrease of crystallization temperature(Tc), melting temperature(Tm) and crystallinity.3. GMA enhances the stability of PLA/PBAT/PHBV blends in thermal. The rheological of PLA/PBAT/PHBV reactive blends increase slightly and the effect of temperature or shear rate on viscosity also remarkable. GMA content or temperature has less effect on viscosity of blends melt with high shear rate which makes processing easier. GMA makes the spinnability PLA/PBAT/PHBV blends significantly improved. Drawing speed of fiber is increase greatly which can up to 126 m/min. At the same time fiber thickness uniformity, the processing with no sticky phenomenon and fiber can be unwinded easily. GMA content and drawing speed have a significantly effect on the mechanical properties of the fibers. Strength is increase while elongation at break is reduce. The balance mechanical strength and toughness of fiber can be achieved when GMA content is 7% and the drawing speed is 70 m/min.