不同后处理条件下聚萘二甲酸乙二酯纤维的结构变化

STRUCTURE CHANGES OF POLY(ETHYLENE-2,6-NAPHTHALATE)FIBERS UNDER DIFFERENT POST TREATMENT CONDITIONS

对不同纺速下制得的聚萘二甲酸乙二酯 (PEN)初生纤维进行了冷拉伸、定长热处理和热拉伸等后处理 .通过WAXS、DSC等测试研究了纤维中结构变化与后处理条件之间的关系 .结果表明 ,较低纺速下所制得的无定形初生纤维在低于Tg 温度下的冷拉伸时发生了应力诱导结晶 ,纤维中生成了α晶体 .同样的初生纤维在定长热处理过程中直至 2 0 0℃仍保持无定形结构 .这些结果说明施加应力相对于升高温度对于α晶体的生成更为重要 .而热拉伸样品中结晶结构的形成与初生纤维的结构有很大关系 ,低纺速下无定形初生纤维在热拉伸后形成α晶体 ,而高纺速下主要含有 β晶体的初生纤维经热拉伸后 β晶体会部分转变为α晶体 ,且 β晶转变为α晶的难易程度取决于初生纤维中 β晶的完善程度 ,初生纤维中 β晶越完善 ,热拉伸时

As\|spun PEN fibers prepared by melt spinning ranged from 0.5 to 10km/min were treated under different conditions like cold drawing.constrained annealing and hot drawing.Structure changes during the treatment were studied through WAXS and DSC testing.The result shows that during the cold drawing process below T g,stretching induced crystallization can occur and thus α \|form crystal formed in the cold drawn samples whose precursor was spun at low speed.However,when the same precursor was subjected to constrained annealing,its amorphous characterstics remain unchanged even the annealing temperature was 200℃.These results may indicate that the stretching stress is more important than elevated temperature in forming α crystals.The crystalline structure of the hot drawn samples depends significantly on the morphology of the precursor fibers.When the as\|spun fiber was prepared at low speed and the fiber structure is predominantly amorphus,hot drawing process will induce α \|form crystals.It is observed that the predominant β \|form crystals in the as\|spun fibers wound at higher speeds were partly transformed into α \|form crystals during the hot drawing.And the level of this transition depends on the perfection of the β \|form crystal in the precursors.The higher the spinning speed,the more perfect the β \|form crystals in the as\|spun fibers,and the lower the level of this transition,and accordingly,the more the remainder of the β \|form crystals in the hot drawn samples.