对不同聚合度和醇解度的聚乙烯醇(PVA)进行溶液改性,改善了PVA的加工性能和热稳定性能。以乙烯-乙烯醇共聚物(EVOH)为基材,通过双螺杆挤出机与改性聚乙烯醇(TPVA)进行熔融共混,制备了改性聚乙烯醇/乙烯-乙烯醇共聚物(TPVA/EVOH)复合膜。通过扫描电子显微镜和X射线衍射仪对复合膜的微观结构和晶体结构进行表征并测试了复合膜的力学性能、阻氧性能和透湿性能。结果表明:复合膜的热稳定性随着TPVA醇解度的增加而下降,随着TPVA聚合度的增加而增强;复合膜的拉伸强度随着TPVA聚合度和醇解度的增加而增大,随着TPVA含量的增加,拉伸强度都逐渐降低;复合膜的阻氧性至少提高了15%左右,氧气透过系数随着TPVA聚合度的增加而增大,随着TPVA醇解度的增加而减小。
Solution modification of polyvinyl alcohol (PVA) with different degrees of polymerization and alcoholysis improved the processing and thermal stability properties of PVA.The modified polyvinyl alcohol/ethylene vinyl alcohol copolymer (TPVA/EVOH) composite film was prepared by melt blending with modified polyvinyl alcohol (TPVA) via twin-screw extruder using ethylene vinyl alcohol copolymer (EVOH) as the substrate.The microstructure and crystal structure of the composite film were characterized by scanning electron microscope and X-ray diffractometer,and the mechanical properties,oxygen barrier properties and moisture permeability properties of the composite film were tested.The results showed that:the thermal stability of the composite film decreased with the increase of TPVA alcoholysis degree,and increased with the increase of TPVA polymerization degree.The tensile strength of the composite film increased with the increase of TPVA polymerization degree and alcoholysis degree,and the tensile strength was gradually decreased with the increase of TPVA content.The oxygen barrier property of the composite film was improved by at least 15%,and the oxygen permeability coefficient increased with the increase of TPVA polymerization degree and decreased with the increase of TPVA alcoholysis degree.
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