摘要
It is a daunting task to develop a promising strategy at an industrial scale for simultaneously ameliorating ductility and gas barrier performance of poly(lactic acid)(PLA)films in the application of green packaging.In this work,biaxial stretching and constrained annealing were employed to prepare transparent PLA films with superior ductility and barrier properties.The oriented nano-sized crystals induced by biaxial stretching were developed into regularαform during constrained annealing,which could not only serve as“nano-barrier wall”to impede the diffusion and dissolution of gas molecules,but also strengthen amorphous chain entanglement network as physical crosslink to enhance ductility.As a result,the as-prepared PLA films exhibited an outstanding comprehensive performance with a low oxygen and water vapor permeability coefficient of 0.733×10^(-14) cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1) and 3.82×10^(-14) g·cm·cm^(-2)·s^(-1)·Pa^(-1),respectively,outstanding ductility with elongation at break of 66.0%,high yield strength of 84.2 MPa,and good transparency of more than 80%at 550 nm.The new insight in the relationship between microscopic amorphous and crystalline structure and macroscopic performance is conducive to alleviating the intrinsic defects of brittle and insufficient barrier PLA films without the aid of any heterogenous modifiers,facilitating their widespread commercialization in the booming sustainable packaging market.
基金
financially supported by the National Key Research and Development Program of China(No.2018YFB0704200)
the National Natural Science Foundation of China(Nos.51803140,52033005,51822305 and 21776186)
the Science and Technology Department of Sichuan Province(No.2018JY0584)
the Postdoctoral Science Foundation of China(No.2019M663496)
the State Key Laboratory of Polymer Materials Engineering(No.sklpme2021-4-03)。