Karthi Rajendran, Vennila Srinivasan and Sankar Govindarajan^*,

Department of Polymer Science, University of Madras, Guindy Campus, Chennai-600025, India

*Corresponding author: E-mail: gsankarphd@gmail.com; gsankarnco@gmail.com

Phenol blocked hexamethylenediisocyanate adducts and polyisocyanates were synthesized and their structure was validated by FTIR, ¹H & ¹³C NMR spectroscopy, TGA, DSC and CO₂ evolution techniques were used to evaluate the deblocking temperature of blocked isocyanates. Gel time studies of blocked isocyanates with terathane polyol and solubility study of blocked isocyanates with different polyols were conducted to demonstrate the structure-property correlation. Epoxy-polyurethane films were produced utilizing the blocked isocyanates reported in this work with epoxy resin and their structure was verified by ATR Spectroscopy. TGA, DSC, shore A hardness, tensile strength and flexural strength analysis were used to investigate the thermal and mechanical characteristics of these films. The findings of deblocking temperature and gel time revealed that unsubstituted phenol blocked isocyanates and polyisocyanates deblock at lower temperatures and cure for a shorter time period than substituted phenol blocked isocyanates. Thermal and mechanical characteristics of epoxy-polyurethane films based on blocked polyisocyanates are satisfactory.

Blocked isocyanates, Deblocking, Epoxy, Polyurethane, Phenol.