采用凝胶渗透色谱仪、核磁共振仪及旋转流变仪研究了热收缩膜专用低密度聚乙烯(LDPE)2420D的分子链结构、流变性能及收缩性能.结果表明:LDPE 2420D的重均分子量达到1.0×105以上,且相对分子质量分布适中,抗撕裂性能优良,为热收缩膜提供了较高的拉伸强度和结晶度;分子链的总体支化数达到12个/1000 C以上,长链支化度较高;透明性好,物品展示性好;2420D具有较高的储能模量,拉伸弹性好,用其制备的薄膜具有优良的力学性能和收缩性能,纵向收缩率达到75%以上.
The molecular chain structure,rheological and shrinkage properties of low density polyethylene (LDPE)2420D were investigated by gel permeation chromatograph,nuclear magnetic resonance,and rotational rheometer. The results show that the weight average molecular weight of 2420D is above 1.0×105 with moderate molecular weight distribution and excellent tear strength,which can be used to produce heat shrinkable film with high tensile strength and crystallinity. The total number of branches of molecular chains reach 12/1000 C, which means high long chain branching. It has high transparency and benefits the display of products. The high energy storage modulus and tensile elasticity of 2420D help to fabricate the films with excellent mechanical and shrinkage properties,whose longitudinal shrinkage ratio is up to 75%.