Improvement of Elastic Modulus and Thermal Stability of Epoxy Resin Using New Curing Agents

Abstract

New curing agents 2,5-diamino-1,3,4-thiadiazole (DATD) and N-(4-hydroxybenzal) N'(4′-hydroxyphenyl) thiourea (HHPT) were synthesised and characterized using FT-IR, 1H-NMR and 13C-NMR analysis. The curing reactions were studied for the epoxy resin diglycidyl ether of bisphenol-A (DGEBA) using new curing agents along with the conventional aromatic diamine 4,4′-diamino diphenyl methane (DDM) for comparison purpose. The curing profiles of DDM, DATD and DATD/HHPT towards DGEBA were examined by Differential Scanning Calorimetry (DSC). Elastic modulus and thermal stability of the cured resins were evaluated using DMA and TGA analysis. When compared with DDM and DATD, the DATD/HHPT curing system accelerated the curing rate due to the presence of phenol molecules in the HHPT. Furthermore, the DATD/HHPT-cured epoxy resin demonstrated higher elastic modulus along with better thermal stability.

Keywords:

• Curing
• 2,5-diamino-1,3,4-thiadiazole,N-(4-hydroxybenzal)n'(4'hydroxyphenyl) thiourea
• Diglycidyl ether of bisphenol-A
• Elastic modulus
• Thermal stability

ACKNOWLEDGMENTS

The authors are grateful to Sri. C. Soundara Raj, Chairman, SNR Sons Charitable Trust, Dr. R. Joseph Xavier, Principal, Dr. R. Mohan Kumar, Professor, and Mr. M.R. Raveendran, Assistant Professor for their guidance and encouragement. The authors are also thankful to Dr. S. Sivanesan, Dean, Anna University, Dr. K. Palanivelu, Director CIPET, and Dr. P. Ramesh, TVS-Lucas, Chennai for their technical help.

Notes

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lpte.