Thermal Degradation of an Anhydride-Cured Epoxy Resin by Laser Heating
A 100-W CO2 continuous laser beam has been used to heat a cycloaliphatic epoxy polymer sample inside a platinum crucible suspended in the glass reaction tube of a Cahn RG Electrobalance®. The beam was transmitted through an IRTRAN-4 entrance window into the system. Calibration of the laser was made with respect to temperatures attained by the platinum crucible and measured with a chromel — alumel thermocouple and a recorder. The electrobalance, which was in an all-glass conventional vacuum system, was used to record the changes of weight with time and obtain the rates of degradation. Chemical analysis, by infrared and mass spectrometry, showed that the major gaseous products formed during degradation were water and carbon dioxide. Other products, such as toluene, pyridine, acetone, methyl formate, hexatriene, methyl acetylene, and butadiene, were found to be present in smaller amounts. The activation energy associated with the weight-loss process was 18 ± 3 kcal/mole. An attempt is made to explain the thermal degradation of the epoxy polymer by postulating a mechanism based on the degradation products and the prevailing conditions in the system.
KeywordsThermal Degradation Laser Heating Platinum Crucible Epoxy Polymer Phthalic Anhydride
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