Román Frida, Colomer Pere, Calventus Yolanda, Hutchinson John M
Departament de Màquines i Motors Tèrmics, Escola Superior d'Enginyeries Industrial, Aeroespacial i Audiovisual de Terrassa, Universitat Politècnica de Catalunya, Barcelona Tech, Carrer de Colom 11, 08222 Terrassa, Spain.
Materials (Basel). 2018 Mar 9;11(3):410. doi: 10.3390/ma11030410.
Two different commercial hyperbranched poly(ethyleneimine)s (HBPEI), with molecular weights (MW) of 800 and 25,000 g/mol, and denoted as PEI800 and PEI25000, respectively, as well as the mixtures with a Diglycidyl Ether of Bisphenol-A (DGEBA) epoxy resin, have been studied using thermal analysis techniques (DSC, TGA), dielectric relaxation spectroscopy (DRS), and dynamic mechanical analysis (DMA). Only a single glass transition is observed in these mixtures by DSC. DRS of the HBPEIs shows three dipolar relaxations: γ, β, and α. The average activation energy for the γ-relaxation is similar for all HBPEIs and is associated with the motion of the terminal groups. The β-relaxation has the same average activation energy for both PEI800 and PEI25000; this relaxation is attributed to the mobility of the branches. The α-relaxation peak for all the HBPEIs is an asymmetric peak with a shoulder on the high temperature side. This shoulder suggests the existence of ionic charge trapped in the PEI. For the mixtures, the γ- and β-relaxations follow the behaviour of the epoxy resin alone, indicating that the epoxy resin dominates the molecular mobility. The α-relaxation by DRS is observed only as a shoulder, as a consequence of an overlap with conductivity effects, whereas by DMA, it is a clear peak.
研究了两种不同的商业超支化聚（乙烯亚胺）（HBPEI），分子量（MW）分别为800和25,000 g/mol，分别表示为PEI800和PEI25000，以及它们与双酚A二缩水甘油醚（DGEBA）环氧树脂的混合物，采用了热分析技术（DSC、TGA）、介电弛豫光谱（DRS）和动态力学分析（DMA）。通过DSC在这些混合物中仅观察到一个玻璃化转变。HBPEI的DRS显示出三种偶极弛豫：γ、β和α。所有HBPEI的γ弛豫平均活化能相似，且与端基的运动有关。PEI800和PEI25000的β弛豫具有相同的平均活化能；这种弛豫归因于支链的流动性。所有HBPEI的α弛豫峰是一个不对称峰，在高温侧有一个肩峰。这个肩峰表明PEI中存在捕获的离子电荷。对于混合物，γ和β弛豫仅遵循环氧树脂的行为，表明环氧树脂主导分子迁移率。由于与电导率效应重叠，通过DRS观察到的α弛豫仅为一个肩峰，而通过DMA观察到的则是一个明显的峰。
