Wu Feng, Zhou Xingping, Yu Xinhai
College of Chemistry, Chemical Engineering and Biotechnology, Donghua University Shanghai 201620 P. R. China
RSC Adv. 2018 Feb 21;8(15):8248-8258. doi: 10.1039/c7ra13233f. eCollection 2018 Feb 19.
A novel resin system was prepared using the glycidyl amide type multifunctional epoxy resin ,,','-tetraglycidyl-4,4'-diaminodiphenylmethane (TGDDM) and latent curing agent dicyandiamide (DICY). The curing reaction mechanism of the TGDDM/DICY system was studied by Fourier transform infrared (FTIR) spectrometry and the non-isothermal cure behaviors of the mixture were investigated with differential scanning calorimetry (DSC) measurements. The FTIR results demonstrated that there were two main reactions occurring in the curing process of the TGDDM/DICY system. The DSC thermogram of the blend exhibited two different cure regimes in the temperature range of 140-358 °C, and the system experienced two autocatalytic curing processes with = 0.45 as the boundary; the corresponding average activation energies calculated by the Kissinger method were 69.7 and 88.7 kJ mol, respectively. In addition, the correlation between activation energy and fractional conversion was determined by applying model-free isoconversional analysis with Flynn-Wall-Ozawa (FWO) and Starink methods. Results showed that both methods revealed similar trends and possessed approximately the same values at each fractional conversion. Activation energy varied greatly with fractional conversion and the possible causes behind the variations were analyzed in detail. The cured TGDDM/DICY exhibited outstanding mechanical and adhesive properties with tensile and shear strengths of 27.1 MPa at 25 °C and12.6 MPa at 200 °C, good dielectric properties with a low dielectric constant of 3.26 at 1000 kHz and a low water absorption of 0.41%.
采用缩水甘油酰胺型多功能环氧树脂四缩水甘油基-4,4'-二氨基二苯甲烷（TGDDM）和潜伏性固化剂双氰胺（DICY）制备了一种新型树脂体系。通过傅里叶变换红外光谱（FTIR）研究了TGDDM/DICY体系的固化反应机理，并用差示扫描量热法（DSC）测量研究了该混合物的非等温固化行为。FTIR结果表明，TGDDM/DICY体系固化过程中发生了两个主要反应。该共混物的DSC热谱图在140 - 358℃温度范围内呈现出两种不同的固化阶段，且该体系经历了两个以α = 0.45为边界的自催化固化过程；通过基辛格方法计算得到的相应平均活化能分别为69.7和88.7 kJ/mol。此外，采用Flynn-Wall-Ozawa（FWO）和Starink方法的无模型等转化率分析确定了活化能E与转化率α之间的相关性。结果表明，两种方法都显示出相似的趋势，并且在每个转化率下具有大致相同的值。活化能随转化率变化很大，并详细分析了变化背后的可能原因。固化后的TGDDM/DICY表现出优异的机械性能和粘合性能，25℃时的拉伸强度和剪切强度分别为27.1 MPa，200℃时为12.6 MPa，具有良好的介电性能，在1000 kHz时介电常数低至3.26，吸水率低至0.41%。
