双向拉伸工艺对聚氟乙烯薄膜性能的影响

Effect of Biaxial Stretching Technology on Property of PVF Film

在聚氟乙烯(PVF)凝胶法成膜的基础上,通过X-射线衍射及万能材料试验仪等手段,研究了在PVF薄膜双向拉伸过程中拉伸比及温度等因素与双向拉伸聚氟乙烯薄膜(BOPVF)性能的关系,讨论了结晶因素对薄膜性能的影响。实验表明,在横向拉伸比固定情况下,随着拉伸比增加,拉伸强度、拉伸模量明显增加,而断裂伸长率则逐渐降低,反之亦然。透光性能也随着拉伸比增加也有所改善。纵向拉伸温度选择:预热辊温度约140～145℃;拉伸辊温度约130～135℃。横向拉伸温度选择:横向拉伸温度比纵向温度约高20～30℃,具体温度取决于薄膜厚度和拉伸速度。在横向拉伸比固定的前提下,PVF薄膜随纵向拉伸比增加,结晶度增加,薄膜拉伸强度也随之提高,而断裂伸长率逐渐降低。

Based on the results of XRD and mechanical tests, the relationship between the stretching ratio and temperature with the property of biax polyvinyl fluorite （PVF） film molded by glation- flowcasting-biaxilly-stretching method was studied, and the influence of crystallization on the property of the film was also discussed. The results showed at given temperature the tensile strength and tensile modulus of the film increased obviously with the increase of the stretching ratio, and the light transmittance was also improved to some extent. For the longitudinal stretching temperature, the preheat roll temperature would be about 140 ～ 145 ℃, and the stretch roll temperature would be about 130 ～ 135 ℃ ; The transversal stretching temperature was 20 ～ 30 ℃ higher than longitudinal stretching temperature, which should depend upon the film thichness and stretching velocity. In the case of keeping the transversal stretching ratio unchanged, the crystallinity of the PVF film increased with the increase of the longitudinal stretching ratio. The increase of the transversal stretching ratio would counteract or decrease the longitudinal orientation and crystallization, leading to the decrease of longitudinal mechanical properties.