Preparation and crystallization behavior of PA 6/PA 612 blended biaxially oriented film
Polyamide 6/612(PA 6/612)cast film was prepared by blending nylon 6(PA 6)and nylon 612(PA 612)at a mass ratio of 80∶20 and was then produced into PA 6/612 biaxially oriented film by longitudinal and transverse stretching.The mechanical properties,melt crystallization behavior,micro-morphology and crystalline structure of the blended film were investi-gated.The non-isothermal crystallization kinetics of the blended film were analyzed using Avrami equation,Ozama equation and Mo Zhishen method modified by Jeriorny method.The results showed that the PA 6/612 biaxially oriented film produced had lon-gitudinal and transverse tensile strengths of 249 and 244 MPa,respectively,a light transmittance of 92％and a haze of 5％and exhibited excellent transparency and mechanical properties;the crystallization temperature and initial crystallization temperature of PA 6/612 cast film were 182.2 ℃ and 188.1 ℃,respectively,showing a shift towards lower temperatures and a decrease in crystallization ability as compared with pure PA 6 and pure PA 612;the crystals of PA 6/612 cast film were strip-shaped,with-out black cross patterns during the isothermal crystallization process,and the crystal size was smaller than that of PA 6 and PA 612 cast films;PA 6/612 cast film was mainly composed of structurally unstable β crystals,with a small amount of α and γ crystals,which was conducive to the biaxially orientation;the Ozama index of PA 6/612 cast film was 3.5-4.4,indicating a homogeneous nucleation mechanism of three-dimensional spherical growth.
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