Preparation And Properties Of Polylactic Acid/ Poly (Butylene Adipate-co-terephthalate) Composites

In recent years, polylactic acid(PLA), acted as a fastest growing biodegradable materal, has attracted more and more attention by the community. There exist a large potentiality for development in disposable food and beverage industry application. Brittleness, lower heat distortion temperature and higher prices compared with polypropylene(PP) are three major problems when generalizing PLA in disposable food and beverage industry application. In this paper, at first, an unsaturated ester compound(DT) as a compatibilizer to improve the compatibility between Poly(butylene adipate-co-terephthalate)(PBAT) and PLA was added. Then, in order to reduce the costs and increase heat distortion temperature, Talc was added into the PLA/PBAT blends. The effect of heat treatment conditions and talc contents on heat distortion temperature was discussed detailedly. Finally, the impact of pulling speed of the sheet on heat shrinkage rate and mechanical properties were researched.The results showed that DT was a efficient compatibilizer to improve the interface adhesion and reduce the size of dispersed phase, which was contributed to a preferable compatibility between PLA and PBAT. When the amount of DT was less than 0.3wt%, the complex viscosity of the blend was increased with a increase of content of DT, nevertheless, the peak frequency was increased with reduction in the amount of DT. Complex viscosity and the number of spherulites within the limits of vision are maximums with added 0.3wt% DT. Elongation at break increased by 46.3% and the same amount of DT gave rise to the excess of impact strength measuring range. When the content of DT exceed 0.3wt%, DT aggravated the fracture and degradation of molecular chain, which led to a worse thermostability and mechanical properties.A peak value of the crystallinity and impact properties appeared when the additive amount of talc was 20wt%. There are a great dispersion and compatibility of talc as the amount of talc was less than 30wt%. A father addition of talc resulted in deterioration of mechanical properties. It has a obvious effect of talc on heat distortion temperature. Heat distortion temperature contained 30wt% talc up to the requirement for disposable catering supplies after annealed at 120℃ for 3 min.Along with an increasing number of PBAT, the discrepancy between machine direction and crosswise direction increased gradually, the heat shrinkage increased and the heat distortion temperature after annealed at 120℃ for 5 min decreased. When the content of PBAT was 20wt%, a honeycomb structure would be observed on the brittle fracture surface of machine direction. With the increase of draw rate, tensile properties in machine direction and crosswise direction presented increased and decreased trend, respectively. Heat treatment resulted in a decrease of tensile properties both in machine direction and crosswise direction with a increase of draw rate. In the machine direction, heat shrinkage was increased with a increase of draw speed. However, the heat shrinkage in crosswise direction contrary to the machine direction, namely, heat shrinkage decreased with a increase in draw speed.