| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 90 === The differences of thermal properties and dielectric properties between amine cured rigid rod epoxies and amine cured flexible epoxy were studied in this thesis.
The rigid rod epoxies of azomethine epoxy (AM), biphenol epoxy (BP) and tetramethyl biphenol epoxy (TMBP) were cured with diaminodiphenylsulfone (DDS) and dicyandiamide (DICY) respectively. The flexible epoxy of diglycidyl ether of bisphenol A epoxy (DGEBA) was cured with DDS and DICY respectively and were compared with cured rigid rod epoxy systems. DSC, TMA, DMA and TGA were used to determine the thermal properties, including the glass transition temperatures, decomposition temperatures, curing conditions and thermal expansion coefficients. The dielectric properties were determined by DEA and LCR. The crosslinking densities were determined by swelling ratio test.
The rigid rod structures of epoxies affect the molecular motion and result in higher curing temperature and longer cure time than flexible epoxies. The DDS cured epoxies have higher glass transition temperature and decomposition temperature than the DICY cured epoxies due to the high functionality and rigid structure of DDS. The AM, BP and TMBP have higher glass transition temperatures than DGEBA due to the rigid rod structure. The bulky methyl substitution on the biphenol main chain of TMBP epoxy decreases the order of polymer packing and reduces the glass transition temperature. The AM epoxy has the longest rigid rod structure, thus the AM epoxy has a higher glass transition temperature than that of BP and TMBP epoxies.
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