【摘要】 制备了经邻苯二甲酸酐(PA)封端的理论数均分子量为10000和30000的聚酰亚胺(PI)薄膜,通过差示扫描热分析(DSC)测定薄膜高温热处理前后玻璃化温度的变化,研究了PA封端对ODPA/ODA聚酰亚胺薄膜热稳定性能的影响。结果表明,封端可有效阻止分子链的无序增长,使聚酰胺酸(PAA)分子量分布变窄;且可明显减少分子链在高温下的反应,表现为热处理前后封端薄膜Tg变化明显小于未封端的薄膜。随着高温热处理时间的延长,短链薄膜Tg增长趋势减缓,长链薄膜的Tg变化直线上升。从高温再聚合、交联反应和端基活动性出发,解释了Tg升高和PA封端有利于提高PI薄膜热稳定性的原因。更多还原

【Abstract】 Polyimide films capped with nonreactive phthalimide end groups were synthesized with theoretical number average molecular mass of 10000 and 30000 calculated using the Carothers equation.The effect of end-capper on the thermal properties was studied by investigating the change of the glass transition temperature(T_g) of films after cured at high temperature.The Gel Permeation Chromatography(GPC) results indicated that the molecular distribution of end capped PAA was smaller than that of the no end-capped one.The Differential Scanning Calorimetry(DSC) results showed PA end-capped polyimide films exhibited slower rising range of the T_g compared to no end cappers films’.With the increasing of curing time,the T_g of the short chain film increased slowly,which of the long chain film increased straightly.The end capper’s effect was explained based on polymerization at high temperature,chain branching/crossing-linking reactions and molecular activity.更多还原