分子链大尺度取向对非晶态聚对苯二甲酸乙二酯结晶行为的影响

THE EFFECT OF ORIENTATION OF GLOBAL CHAIN ON CRYSTALLIZATION BEHAVIOR OF AMORPHOUS POLYETHYLENE TEREPHTHALATE

用ＤＳＣ和溶剂诱导结晶（ＳＩＮＣ）的方法对比研究了（ＧＯＬＲ）态和未取向聚对苯二甲酸乙二酯（ＰＥＴ）纤维样品的结晶行为．实验结果表明，样品的大尺度取向可有效地降低样品的冷结晶温度（Ｔｃｃ），证明大尺度取向对样品的结晶行为可起到促进作用．

In the rubbery state of amorphous polymers under uni axial drawing,the glolal chain orientation will relax in orders of magnitude slower than the relaxation of local segmental orientation.When this state of hot drawn sample is frozen at temperatures lower than its glass transition, T g,an amorphous state with high global chain orientation but nearly random segmental orientation(GOLR) would result.The characteristic features of GOLR state are large recovery of the elastic deformation β ′ of global chain on being heated to temperatures above T g ( β ′=70%～90%) and very small birefringence( Δn～ 10 -4 ).The effect of global chain orientation (GCO) on crystallization behavior of amorphous polyethylene terephthalate (PET) fibres is studied by differential scanning calorimetry (DSC) performed at different heating rates and solvent induced crystallization (SINC) method by comparing the crystallization behavior of PET as spun fiber in GOLR state ( β ′=34 3%, Δn =1×10 -3 ,ρ=1 3362g/cm 3 with that of its thermally relaxed(105℃,3min in the air) PET sample ( β ′=5 4%,ρ=1 3362g/cm 3).The results indicate that the cold crystallization temperature, T cc ,is effectively depressed by the GCO.That means the global chain orientation accelerates the development of crystallization.