摘要
目的利用双向拉伸力场调控环境友好聚乙烯醇(PVA)的微观结构,制备高阻隔双向拉伸PVA(BOPVA)包装薄膜,研究BOPVA薄膜的微观结构及力学、光学、阻隔和耐水性能,探讨其应用可行性。方法结合分子复合改性技术实现PVA的热塑加工,利用双向拉伸设备提供合适的温度场和应力场,制备不同拉伸倍率的BOPVA薄膜,表征其结晶结构与取向行为,测试其拉伸、撕裂和穿刺强度以及透明度、氧气渗透系数(P_(O2))和水溶性。结果双向拉伸力场可诱导PVA结晶,随拉伸倍率增加,BOPVA内部晶体与分子链沿面内方向取向,熔点和结晶度提高,晶体尺寸增大;双向拉伸极大提高了PVA薄膜的拉伸强度和抗穿刺性能,拉伸3×3倍后,拉伸强度和穿刺强度分别达146.4 MPa和357.9 N/mm;BOPVA薄膜透明性和耐水性均优于未拉伸样品,600 nm波长处的透光率达88.3%,在水中浸泡1 h质量损失率低至4.4%;双向拉伸后,PVA自由体积下降,氧气阻隔性提升,薄膜的P_(O2)低至4.48×10^(-15)m^(3)·cm·m^(-2)·s^(-1)·Pa^(-1)。以市售EVOH/PA/PE五层共挤出复合膜作为参比,阻隔改善因子(BIF)达34.1。结论双向拉伸可有效提高PVA的阻隔性和耐水性,促进环境友好PVA薄膜在阻隔包装领域的应用。
The work aims to regulate the microstructure of poly(vinyl alcohol)(PVA)through biaxial stretching to prepare high-barrier biaxially stretched PVA(BOPVA)packaging films and investigate their microstructure as well as mechanical,optical,barrier and water-resistant properties while discussing their usability.BOPVA films with different stretching ratios were prepared by adopting molecular complexation technology to achieve the thermal processing of PVA and utilizing a biaxial stretching machine to provide appropriate temperature and stress fields.The crystalline structure and orientation behavior of the films were characterized and their tensile,tear and puncture strengths as well as light transparency,oxygen permeability coefficient(P_(O2))and water solubility were tested.The biaxial stretching could induce the orientation of crystals and molecular chains within PVA along the in-plane direction,and with the increase of stretching ratio,the melting point,degree of crystallinity and crystal size of PVA gradually increased.Biaxial stretching enhanced tensile strength and puncture resistance of PVA films.Upon 3×3 stretching,the tensile strength and puncture strength of BOPVA films reached 146.4 MPa and 357.9 N/mm respectively.BOPVA films exhibited superior transparency and water resistance,with a light transmittance of 88.3%at a wavelength of 600 nm and a weight loss rate of only 4.4%after immersion in water for 1 h.After biaxial stretching,the free volume of PVA decreased,and as a result,the oxygen barrier properties of the film were improved,with the oxygen permeability coefficient(P_(O2))dropping to 4.48×10^(-15)m^(3)·cm·m^(-2)·s^(-1)·Pa^(-1).With a commercially available EVOH/PA/PE five-layer co-extruded composite film as a reference,the barrier improvement factor(BIF)of BOPVA films reached up to 34.1.Biaxial stretching can effectively improve the barrier properties and water resistance of PVA,promoting the application of environmentally friendly PVA films in barrier packaging.
作者
曾书龙
赵崇滔
李莉
ZENG Shulong;ZHAO Chongtao;LI Li(National Key Laboratory of Advanced Polymer Materials,Institute of Polymer Science of Sichuan University,Chengdu 510065,China;College of Light Industry and Food Engineering,Guangxi University,Nanning 530004,China)
出处
《包装工程》
北大核心
2025年第15期37-45,共9页
Packaging Engineering
基金
国家自然科学基金(U21A2091)
天府永兴实验室科技攻关任务重点项目(2023KJGG12)。
关键词
聚乙烯醇
双向拉伸
氧气阻隔
包装薄膜
结构与性能
poly(vinyl alcohol)
biaxial stretching
oxygen barrier
packaging film
structure and properties
