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通过明胶链上的-NH2与低分子酸酐封端的聚酰胺酸链端酸酐首先在较高温度下缩合反应生成改性预聚体,然后再对改性预聚体扩链,得到明胶改性聚酰胺酸。通过测定明胶改性聚酰胺酸的特性黏度,研究了改性预聚体反应阶段不同反应条件对聚合物特性黏度的影响,同时采用红外光谱和示差扫描量热测定了明胶改性聚酰胺酸的结构与热性能。结果表明,在改性预聚体合成阶段,当明胶用量为35%、反应温度为40℃和反应时间为25min时,明胶改性聚酰胺酸的特性黏度最大。经过明胶改性,改变了聚酰胺酸的结构,使其化学亚胺化薄膜的玻璃化温度比聚酰胺酸化学亚胺化薄膜的降低39℃。
The polyamic acid anhydride end-capped with -NH2 on the gelatin chain and the low molecular anhydride firstly forms a modified prepolymer by condensation reaction at a higher temperature and then extends the chain of the modified prepolymer to obtain the gelatin-modified poly Amic acid. The intrinsic viscosities of gelatin-modified polyamic acid were determined. The effects of different reaction conditions on the intrinsic viscosity of the modified prepolymer were studied. The properties of gelatin-modified polyamic acid were determined by infrared spectroscopy and differential scanning calorimetry Structure and thermal properties. The results showed that the intrinsic viscosity of gelatin-modified polyamic acid was the highest when the amount of gelatin was 35%, the reaction temperature was 40 ℃ and the reaction time was 25 min in the synthesis stage of modified prepolymer. After gelatin modification, the structure of the polyamic acid was changed so that the chemical imidization film had a glass transition temperature of 39 ° C lower than that of the polyamic acid chemical imidization film.