薄膜用聚丙烯树脂熔融态PVT行为的研究

利用PVT 10 0分析仪对 5种不同牌号的双向拉伸用聚丙烯 (BOPP)树脂的压力 体积 温度 (PVT)特性进行了测定 ,并利用Tait方程法得出BOPP熔体的热膨胀系数 (α)随温度和等温压缩系数 (β)随压力的变化关系 .研究结果表明 ,在相同条件下 ,牌号为S2 8C的BOPP熔体的热膨胀系数、等温压缩系数和结晶熔融温度分别低于其它牌号 ,因此 ,我们推断S2 8C在冷片形成过程中的体积形变较小 ,可避免由于收缩产生的模片表面缺陷 ,进而减少在后续双向拉伸过程中的破膜现象

STUDY OF PVT BEHAVIOR OF BIAXIALLY ORIENTED POLYPROPYLENE RESINS IN THE MELTING STATE

The PVT data of five kinds of biaxially oriented polypropylene (BOPP) Resins was measured by the PVT 100 apparatus.Thermal expansion coefficients ( α ) and isothermal compressibility ( β ) were evaluated from Tait equation in the melting state and then compared with those fitted with the value of experiment.The results showed that it was reasonable to calculate α and β with Tait equation in the melting state.At the same time,it was found that thermal expansion coefficients,isothermal compressibility and the melting temperature ( T m ) of one of BOPP melts (S28C) were lower than those of the others in the same test conditions,indicating that the volume deformation of S28C resin is less so that it could be realized to avoid arising surface defects of the film (biaxially oriented polypropylene film) due to contracting,thereby decrease damage to the film in the subsequence process.Accordingly superior processing properties of S28C resin are confirmed from PVT speciality.