长链乙烯酯改性聚乙烯醇热塑加工性能的研究

Thermal-processing Properties of Poly( vinyl alcohol) Modified by Vinyl Ester with Long Chain

通过山梨醇和甘油复配增塑改善长链乙烯酯改性聚乙烯醇(PVA)的热塑加工性能,采用差示扫描量热仪、高压毛细管流变仪、万能试验机等研究了复配增塑剂与改性PVA的相互作用及其对改性PVA热性能、流变性能、力学性能、溶胀性能等的影响。结果表明,山梨醇和甘油复配增塑剂中的羟基可与改性PVA分子链中的羟基形成氢键,减小了PVA分子链间氢键相互作用,使体系黏度减小,分子链的活动性增强,降低了改性PVA熔点,改善了PVA熔体流动性,有利于实现PVA的热塑加工。复配增塑剂增加了PVA的自由体积,使PVA分子链的运动更加容易,提高了材料的柔韧性及断裂伸长率,减少PVA对水的吸收。当增塑剂含量为10%时,复配增塑剂不易析出,可同时改善改性PVA的流变性并使材料保持优异的力学性能。

In this paper, the thermoplastic PVA modified by vinyl ester with long chain was plasticized by sorbitol and glycerol to improve its thermal plastic property. The interaction between PVA and plasticizers, thermal properties, rheological properties, mechanical properties as well as swelling properties of modified PVA were investigated by DSC, capillary rheometer and universal testing machine, etc. The results showed that the hydroxyl of plasticizers can form strong hydrogen bonding with PVA molecular chain, reduce the intra and inter-molecular hydrogen bond of PVA, decrease its melt viscosity and melting point, improve the flowability, thus benefit in realizing the thermal-processing of modified PVA. Plasticizers increased the free volume of PVA, which made PVA molecular chains move more easily, improved the flexibility and elongation at break of PVA and reduced the absorption of water to PVA. When the content of plasticizer was 10%, the glycerol was hardly precipitated from the modified PVA, the rheological properties of modified PVA were improved and well mechanical properties were maintained.