LDPE/m-nZVI复合膜的制备及性能

Preparation and Properties of LDPE/m-nZVI Composite Films

为克服脱氧剂小袋包装与食品混装带来的安全问题,采用硼氢化钾(KBH4)液相还原法制备了油酸钠(NaOl)改性纳米零价铁(m-nZVI),将其与低密度聚乙烯(LDPE)熔融共混后热压成膜,制备了包装用LDPE/m-nZVI阻氧复合膜。利用傅里叶变换红外光谱仪、热重分析仪、差示扫描量热仪、万能拉伸试验机和气体渗透仪对复合膜的结构与性能进行表征和测定。结果表明:m-nZVI和LDPE的复合是物理共混;加入m-nZVI后,LDPE的热稳定性基本不变;随着m-nZVI含量的增加,复合膜的抗拉强度和断后伸长率先增大后减小,m-nZVI质量分数为2%时,抗拉强度和断后伸长率达到最大,较LDPE膜分别提高了41.4%和23.4%;复合膜的氧气透过系数也呈现出先减小后增大,当m-nZVI质量分数为3%时,复合膜的氧气透过系数最小,较LDPE膜降低了40.9%。复合膜结晶过程中,m-nZVI起异相成核的作用,改善了复合膜的结晶行为,使复合膜的结构和性能得到改善,力学性能和阻隔性能都得到提高。

In order to overcome the safety problems caused by the mixed-packaging of small-bag-deoxidizer and foods,sodium oleate(NaOl)modified nano zero-valent iron(m-nZVI)was prepared by liquid phase reduction method with potassium borohydride(KBH4),which was fused with low density polyethylene(LDPE)and pressed into film by thermal press.The LDPE/m-nZVI composite film for packaging was prepared.The resultant materials were characterized and measured by Fourier transform infrared spectroscopy,thermogravimetric analysis,differential scanning calorimetry,universal testing machine and gas transmission rate tester.The results show that m-nZVI and LDPE were physical-blending.The presence of m-nZVI had no effects on thermal stability of LDPE.With increase in m-nZVI,the tensile strength and elongation at break of the composite films increased and then decreased.With m-nZVI weight fraction at 2%,the tensile strength and elongation at break of the composite films reached the maximum,increased by 41.4%and 23.4%respectively compared with the virgin LDPE film.The oxygen transmission coefficient of the composite film also decreased first and then increased.When the mass fraction of m-nZVI was 3%,the oxygen permeability coefficient of the composite film was the smallest,which was 40.9%lower than that of the virgin LDPE film.The addition of m-nZVI improved the composite film’s crystallization behaviors,and m-nZVI played the role of heterogeneous nucleation by improving the crystallization behavior of composite film,as well as the structure and properties of composite film,and enhanced the mechanical properties and barrier properties.