Curing kinetics and thermal stability of diglycidyl ether of bisphenol |
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Authors: | P Sharma V Choudhary A K Narula |
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Institution: | (1) School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Kashmere Gate, Delhi, 110006, India;(2) Centre for Polymer Science & Engineering, Indian Institute of Technology, Hauz Khas, New Delhi, 110016, India |
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Abstract: | Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of varying molar ratios of aromatic imide-amines
and 4,4′-diaminodiphenylsulfone (DDS) were investigated by the dynamic differential scanning calorimetry. The imide-amines
were prepared by reacting 1 mole of benzophenone 3,3′,4,4′-tetracarboxylic acid dianhydride (B) with 2.5 moles of 4,4′-diaminodiphenyl
ether (E)/ or 4,4′-diaminodiphenyl methane (M)/ or 4,4′-diaminodiphenylsulfone (S) and designated as BE/ or BM/ or BS. The
mixture of imide-amines and DDS at ratio of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 were used to investigate the curing
behaviour of DGEBA.
The multiple heating rate method (5, 10, 15 and 20°C min−1) was used to study the curing kinetics of epoxy resins. The peak exotherm temperature was found to be dependent on the heating
rate, structure of imide-amines as well as on the ratio of imide-amine: DDS used. A broad exotherm was observed in the temperature
range of 180–230°C on curing with mixture of imide-amines and DDS. Curing of DGEBA with mixture of imide-amines and/or DDS
resulted in a decrease in characteristic curing temperatures. Activation energy of curing reaction as determined in accordance
to the Ozawa’s method was found to be dependent on the structure of amine. The thermal stability of the isothermally cured
resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere. The char yield was highest in case of resins
cured using mixture of DDS: BS (0.25:0.75; EBS-3), DDS: BM (0.5: 0.5; EBM-2) and DDS: BE (0.5: 0.5; EBE-2). |
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Keywords: | curing kinetics DGEBA epoxy resins imide-amines thermal stability |
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