Biodegradable poly(butylene adipate-co-terephthalate)/poly(vinyl acetate) blends with improved rheological and mechanical properties

Poly(butylene adipate-co-terephthalate) (PBAT) are expected to be widely used for production of biodegradable film materials. However, poor rheological properties, low yield strength and modulus of PBAT limit its applications in some field. Herein, PBAT/poly(vinyl acetate) PVAc blends were prepared by melt mixing to overcome aforementioned shortcomings. The miscibility, phase morphology, thermal properties, rheological properties and mechanical properties of PBAT/PVAc blends were studied. Miscibility analysis showed that PBAT/PVAc blends were immiscible two-phase system. The uniform dispersion of PVAc in PBAT matrix was observed in SEM images. From thermal properties analysis, the incorporation of PVAc accelerated crystallization rate and enhances crystallization ability of PBAT. Rheological analysis demonstrated that storage modulus, loss modulus and complex viscosity of PBAT were obviously improved when PVAc was added due to the high viscosity of PVAc in melt state. Mechanical data indicated incorporation of PVAc could enhance modulus and yield strength of PBAT. When the content of PVAc was 30%, Young's modulus and yield strength of PBAT were improved about 105% (from 203 to 416 MPa) and 53.3% (from 7.5 to 11.5 MPa), respectively. In addition, the elongation at break and tensile strength of blends decreased with the increase in PBAT loading, but all the PBAT/PVAc blends maintained the elongation at break of more than 700%, which meets the requirements of most applications.