【摘要】 聚芳醚酮(Poly(oxy—1,4—phenylene carbonyl—1,4—phenylene),简称 PEK)是一种含有苯环的耐高温聚合物。本文用 DSC 法研究了 PEK 的玻礅化转变和熔融行为。PEK 是一种半结晶的高聚物。骤冷的 PEK 再升温时,可以看到十分明显的玻璃化转变过程和冷结晶过程,它的玻璃化转变温度 T_g 为158.2℃,T_g 下的热容变化△C_p 为0.244J/g·K,平衡冷结晶温度 T°(?)为179.9℃,平衡熔融温度 T°m(H)为379.0℃,熔融热△H_m(H)为53.5J/g。骤冷 PEK 在不同温度(250～310℃)等温结晶15min 后,其 DSC 曲线上可以看到数个熔融峰。随结晶温度升高,温度较高的主熔融峰温度 T_m(H)略有升高,温度较低的熔融峰温度 T_m(L)大约在结晶温度以上20℃;温度较高的熔融峰面积△H_m(H)不变,温度较低的熔融峰面积△H_m(L)增加,△C_p 下降,T_g 升高。将骤冷的 PEK 从略高于 T_g 的温度(159.0℃)以不同速率降温,再升温时,可以看到 PEK 玻璃化转变的滞后现象。随降温速度下降,滞后现象变得十分明显。滞后峰面积△H_h 与降温速度的对数呈线性关系。更多还原

【Abstract】 Poly(oxy-1,4-phenylenecarbonyl-1,4-phenylene)(PEK)is one of the high-temperature-resistant polymers containing phenylene groups.This paper presents a study ofthe glass transition and the melting behavior of PEK by DSC.PEK is a semicrystal.Whenquenched PEK is reheated,its process of glass transition and cold crystallization can be seenvery clearly.Its glass transition temperature,T_g,is 158.2℃,the heat capacity at that tempera-ture,△C_p,increases by 0.244 J/g·K.The equilibrium melting temperature,T_m(H),is379.0℃.The equilibrium cold crystllization temperature,T_c,is 179.9℃.Melting heat,△H_m(H),is 53.5 J/g.DSC melting traces of isothermal crystallization from the glass state ofquenched PEK at 250～310℃ for 15 min show two melting peaks.With the increase ofisothermal temperature,the higher melting peak temperature,T_m(H),increases a little,thelower,T_m(L),is about 20℃ above the isothermal temperature,the H_m(H)does notchange,the melting heat at lower temperature end,H_m(L),insreases.DSC traces ofquenched PEK heated to just above T_g(159℃)and then cooled at various chosen ratesshow glass transition hysteresis,when reheated.With the descent of the cooling rate,thehysteresis is more and more clear.The area of the hysteresi heat,△H_h,and the logarithm ofthe cooling rate are linearly correlated.更多还原