Studies of Thermosetting Resin. I. The Infrared Analysis of Cured Epoxy Resins

To pulverize the cured hard resins for the infrared KBr technique, the method using a file is very simple and convenient. From the infrared spectra of the powder of cured epoxy resins using the KBr-pellet technique, the curing agent used can be readily identified by type whether it is an amine or an acid-anhydride type by the absence or presence of the carbonyl absorption band. Furthermore, in the case of the acid anhydride-cured epoxy resins, the acid anhydride used as the curing agent can be identified by type from the spectra of the resin pyrolyzate. Namely, PA, THPA, EMTHPA, HET, and DDSA may be identified immediately from the spectra of pyrolyzates between room temperature and 300°C, and HHPA, from the spectrum of the pyrolyzate between 300 and 350°C. The results of these experiments are summarized in Table II. PMDA used as a curing agent can not be so straightforwardly identified as in the other cases, but even this may be identified by a comparison of the spectra of the pyrolyzates of PMDA-cured resin with those of the pyrolyzates of each resin.