聚乙烯醇中空容器的制备及热处理

Preparation of Polyvinyl Alcohol Hollow Container and Its Heat Treatment

以含水和多羟基化合物的复合改性剂,通过分子复合和增塑,实现聚乙烯醇(PVA)的热塑加工,制备了PVA中空容器。采用高压毛细管流变、X射线衍射、动态力学热分析、阻隔性能、水接触角等测试方法,研究了复合改性PVA体系的熔体流变行为,以及不同热处理条件对所得PVA中空容器综合性能的影响。结果表明,复合改性体系熔体黏度满足吹塑要求,吹塑所得中空容器外观良好;热处理可调控PVA中空容器的水含量,进而调控其结晶度、熔点(Tm)和玻璃化转变温度(Tg),改善其力学性能和阻隔性能。120℃热处理2 h后,PVA容器的结晶度从22.2%提升至34.7%,Tg从-3℃提升至30℃,拉伸强度从30.4 MPa增加至80.3 MPa,石油醚的渗透速率由2.33 g·mm/(m2·d)减少至0.73 g·mm/(m2·d),水接触角从31.0°增加至78.1°。

Polyvinyl alcohol(PVA) hollow containers were successfully prepared through thermal processing,based on intermolecular complexation and plasticization,by adopting water and polyhydroxy compounds as composite modifiers.By high pressure capillary rheology,X-ray diffraction,dynamic mechanical properties,barrier properties and water contact angle testing methods,the melt rheological behaviors of the modified PVA system and the effects of different heat treatment conditions on the comprehensive properties of PVA hollow containers were investigated.The results show that the melt rheological behaviors of the modified system could meet the requirements of the blow molding,and the hollow containers obtained by blow molding exhibit good appearance.Heat treatment could control the water content of PVA hollow container,and adjust its crystallinity,melting point(Tm) and glass transition temperature(Tg),which improve its mechanical properties and barrier properties.After the heat treatment at 120 ℃ for 2 h,the crystallinity of the PVA hollow container increases from22.2% to 34.7%,Tgincreases from-3 ℃ to 30 ℃,the tensile strength increases from 30.4 MPa to 80.3 MPa,the permeability to petroleum ether decreases from 2.33 g· mm/(m2· d) to 0.73 g· mm/(m2· d),and the water contact angle increases from 31.0° to 78.1°.