Preparation And Properties Of Poly (Lactic Acid)/ Poly (Butylene Adipate-co-terephthalate)-based Biodegradable Blend Films

Recently,biopolymer based plastic materials are regarded as potential alternative for conventional plastics of fossil fuel origin in order to compensate depleting petroleum resources and address environmental pollution issues.Poly(lactic acid)(PLA)is one among the biopolymers which is rapidly commercialized for food packaging application.However,PLA usually exhibits high brittleness and low crystallization rate,which limit the applications of PLA.Poly(butylene adipate-co-terephthalate)(PBAT)has perfect ductility and biodegradability.In the present dissertation,PBAT can be used to enhance the mechanical properties of PLA,and the novel bio-sourced PLA/PBAT composites with excellent performance were prepared.Moreover,the thermoplastic starch(TPS)was added to PLA/PBAT blends,PLA/PBAT/TPS blends were prepared to reduce costs.The main contents and conclusions of this paper are as follows:With Joncryl ADR-4370F(ADR)as the compatibilizer and super fine talc powder(Talc)as the nucleating agent,PLA/PBAT were melt-blended,then extruded into blown films.The thermal properties,crystallization behavior,torn surface morphology of blown films,mechanical properties,barrier permeability of the PLA/PBAT blown films were investigated.It indicated that the addition of PBAT improved the flexibility of PLA.With increasing PBAT content from 40wt% to 70 wt%,the PLA/PBAT blown films showed decreased tensile strength and modulus,the elongation at break was greatly increased.The influence of PBAT to oxygen resistance properties and water vapour resistance properties of blown films is little.ADR could enhance the compatibility of the PLA/PBAT blown film materials.PLA,PBAT and thermoplastic starch(TPS)were melt-blended and extruded into blown films.The content of PBAT was fixed at 50wt% with alternating the proportion of PLA and TPS.The mechanical properties,optical properties,thermal properties,crystallization behavior,torn surface morphology of blown films,hydrophobicity,oxygen permeability and enzymatic hydrolysis of the PLA/PBAT/TPS blown films were studied.The results showed that the cold crystallization temperature of PLA decreased about 40 °C,indicating the enhancement of the cold crystallization ability of PLA in PLA/PBAT/TPS blown films.With increasing TPS content,tensile strength of PLA/PBAT/TPS films decreased,but the elongation at break increased.It showed that PLA/PBAT/TPS blown films exhibited evident ductile fracture from scanning electron microscope(SEM).Water contact angle and oxygen permeability coefficient analysis indicated that the PLA/PBAT/TPS blown films had superior applications performance.