Mechanical Properties of the Pre-oriented Polylactic Acid Films
Polylactic acid(PLA)is a biodegradable,eco-friendly green polymer material.PLA films prepared by melt stretching exhibit high modulus and toughness,showing wide applications in the packaging industry.Studying the mechanical properties of pre-oriented PLA films has a significant practical importance.In this paper,the toughness and yield activation energy of the samples were calculated using the essential work of fracture method and Eyring theory.The results show that,with the increase of draw ratio,the film crystallinity and yield strength increase,and the strain hardening phenomenon becomes evident.The toughness of PLA films with different draw ratios was studied using the essential work of fracture method.As the draw ratio increases,the specific essential work of fracture gradually increases,while the specific non-essential work of fracture first increases and then decreases.The increase of crystallinity inhibits the expansion of internal defects,leading to a linear increase in the necking-tearing plastic work.During the slow stretching,the yield failure originates from the plastic deformations in the amorphous regions,producing a yield activation energy of about 13-14 kJ/mol.The rapid stretching leads to the slipping of the crystalline-amorphous interfaces,producing a yield activation energy of only 7 kJ/mol.
Polylactic AcidMelt Stretch MoldingEssential Work of FractureYield Activation Energy
万方数据
维普
