Preparation And Properties Of PLA Blends For Films Application

Polylactic acid(PLA)is a widely used biodegradable material.PLA has rigidity and transparency similar to polystyrene(PS)and polyethylene terephthalate(PET)and has high strength and biodegradability.However,its inherent brittleness,narrow processing window,low crystallization rate limit it large scale-application.In order to expand its application,it must be modified by processing.This paper studied three blending systems:(1)PLA/PBAT blends with the chain extender;(2)PLA/PBAT/ADR blowing films;(3)PLA/PBAT/P(3HB-co-4HB)blends blown film.The main contents and conclusions of the dissertation are as follows:Biodegradable poly(lactic acid)/poly(butylene adipate-co-terephthalate)(PLA/PBAT)blends were prepared using melt blending in the presence of chain extender.The Joncryl ADR-4370F(ADR)was used as the chain extender.The effect on mechanical properties,rheological behavior,morphology and thermal behavior of the blends was investigated.The mechanical properties were markedly improved by incorporation of 0.15 phr ADR,e.g.the elongation at break increased from 23.5%to 410.3%and the notched Izod impact strength increased from 7.5 to 33.4 KJ/m~2 for the PLA/PBAT/ADR blends.Morphological observation through scanning electron microscopy revealed that the compatibility of the PLA/PBAT blends was greatly enhanced by the incorporation of ADR.The interfacial adhesion was improved between PLA phase and PBAT phase.These findings contributed new knowledge to the additives area and gave important implications for manufacturing biodegradable polymer packaging material.Biodegradable poly(lactic acid)/poly(butylene adipate-co-terephthalate)(PLA/PBAT)blends and films were prepared using melt blending and blowing films technique in the presence of chain extender-ADR.The morphological,mechanical,rheological,thermal and crystalline properties of the PLA/PBAT/ADR blown films were studied.SEM micrographs of the films revealed more ductile deformation with increasing PBAT content.The addition of PBAT,enhanced the toughness of the PLA film.Tensile tests indicated that the elongation at break increased from 7.1%to 715.9%in the transverse direction and from20.5%to 334.6%in the machine direction.The sealing strength of 40/60/0.15PLA/PBAT/ADR film was the highest among all the samples up to 9.44 N/15mm.The sealing strength is an important performance of the shopping bag.Rheological behavior indicated the enhanced elastic behavior would be benefit for blend during the practical production process.These findings gave important implications for designing and manufacturing polymer packaging materials.The PLA/PBAT/P(3HB-co-4HB)blends and films were prepared by melt blending and blowing films.The morphology of teared surface,mechanical properties,rheological properties,thermal properties and soil degradation behavior of PLA/PBAT/P(3HB-co-4HB)films were studied.The rheological properties showed that the addition of P(3HB-co-4HB)improved its processability.DSC results showed that the compatibility of PLA/PBAT increased with the addition of P(3HB-co-4HB),and the addition of P(3HB-co-4HB)also promoted the crystallization of PLA.The addition of P(3HB-co-4HB)increased the degradation performance of the films.