ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Isocyanate-free urethane vinyl ester resin: preparation, characterization and thermal and mechanical properties investigation

Soheila Ghasemi and Milad Ghezelsofloo

Department of Chemistry, College of Sciences, Shiraz University, Shiraz, Iran

E-mail: ghasemis@shirazu.ac.ir

Received: 22 June 2022  Accepted: 13 October 2022

Abstract:

The urethane vinyl ester resins (UVERs) with high chemical resistance and mechanical properties such as superior elongation are one of the essential classes of thermoset polymers. Herein, we describe the synthesis of UVER without the use of isocyanate. The use of isocyanate as the primary starting material in the polyurethane production might cause environmental risks; thus, non-isocyanate polyurethane (NIPU) can be prepared without applying isocyanate. Initially, glycidyl methacrylate (GMA) was converted to cyclic carbonate of GMA (CGMA) by applying atmospheric pressure of carbon dioxide and tetrabutylammonium bromide (TBAB) as a catalyst. Formation of product was confirmed by observing carbonyl of the cyclic carbonate peaks and disappearing the epoxy peaks in FT-IR and NMR spectra. Afterward, CGMA was treated with different diamines (ethylenediamine, hexa-, hepta-, octa- and nonamethylenediamine, and m-xylylenediamine) to produce UVER. The detection of new bonds of the urethane groups and the elimination of the peak of cyclic carbonate groups via FT-IR and NMR approved the cyclic carbonate conversion into the hydroxyurethane system. Finally, VER is cured using different percentages of non-isocyanate-based UVER (0, 30, 40, 50 and 70%) applying benzoyl peroxide and N, N-dimethylaniline in the role of initiator and accelerator, respectively. Various characterization techniques such as FT-IR and ATR spectroscopy, rheometery, DSC, TGA and tensile test are conducted to confirm different weight ratios of UVER-VER% synthesis.

Graphical Abstract

Synthesis and characterization of UVER without the use of isocyanate were described. Initially, glycidyl methacrylate (GMA) was converted to cyclic carbonate of GMA in the presence of carbon dioxide. Afterward, CGMA was treated with different diamines to produce UVER. Finally, VERs are cured using different percentages of non-isocyanate-based UVERs.

Keywords: Cyclic carbonate; Glycidyl methacrylate; Non-isocyanate polyurethane; Vinyl ester urethane resin

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02547-9

Chemical Papers 77 (2) 1165–1180 (2023)