含硅氧烷链段和聚苯醚结构的芳香族聚酰胺的制备及其对环氧树脂的增韧改性

Preparation of an aromatic polyamide with a poly(phenylene oxide)structure containing siloxane segments and its use in toughening epoxy resin

以端氨基聚二甲基硅氧烷(ATPDMS)和聚苯醚(PPO)为原料,采用一锅缩聚法合成了一种含硅氧烷链段和聚苯醚结构的芳香族聚酰胺(PAPM),并通过傅里叶变换红外光谱(FT-IR)和核磁共振(NMR)对其进行了结构表征。将PAPM作为增韧改性剂,与固化剂甲基六氢苯酐(MHHPA)一起加入环氧树脂(E51)中制备了E51/MHHPA/PAPM固化物。测试了PAPM和E51的相容性,结果表明,当添加量为5%~15%(质量分数)时,PAPM与E51在固化后的相容性良好,没有发生宏观可见光尺度上的相分离。力学性能测试结果表明:当PAPM添加量为15%时,环氧固化物的临界应力强度因子(K)相比不添加PAPM的环氧体系增加了112.2%;当PAPM添加量为5%时,环氧固化物的储能模量相比不添加PAPM的环氧体系增加了56.6%。采用扫描电子显微镜(SEM)对增韧改性材料的断面形貌进行了分析,结果表明其断裂面呈现漩涡状裂纹结构,断裂表现为韧性断裂。差示扫描量热法(DSC)测试结果表明,当PAPM添加量为15%时,环氧固化物的玻璃化转变温度(T_(g))相对于不含PAPM的环氧体系提高了28.2℃。

An aromatic polyamide(PAPM)with a poly(phenylene oxide)(PPO)structure containing siloxane segments has been synthesized by a one-pot polycondensation method using amino-terminated polydimethylsiloxane(ATPDMS)and poly(phenylene oxide)as raw materials.Its structure was characterized by Fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance(NMR)spectroscopy.An E51/MHHPA/PAPM cured product was prepared by adding PAPM as a toughening modifier and a curing agent(methyl hexahydrophthalic anhydride,MHHPA)to epoxy resin(E51).The compatibility of PAPM and E51 was tested,and the results showed that when the addition amount was 5%-15%(mass fraction),the compatibility of PAPM and E51 after curing was good,with no visible phase separation on the macroscopic light scale.Tests of mechanical properties showed that when the addition amount of PAPM was 15%,the critical stress intensity factor(K)of the cured epoxy resin increased by 112.2%compared with that of the epoxy system without PAPM.When the addition amount of PAPM was 5%,the storage modulus of the cured epoxy resin increased by 56.6%compared with that of the epoxy system without PAPM.The cross-section morphology of the toughened modified material was analyzed by scanning electron microscopy(SEM).The results showed that the fracture surface presented a whirlpool crack structure,and the fracture was ductile fracture.Differential scanning calorimetry(DSC)showed that when the addition amount of PAPM was 15%,the glass transition temperature(T)of the cured epoxy resin increased by 28.2℃compared with that of the epoxy system without PAPM.