Effect of resorcinol-based chain extenders chemical structure on the enhanced properties of polyurethane elastomers

Abstract

Two series of polyurethane elastomers with resorcinol derivatives in the polymer backbone were synthesized by chain extending isocyanate end-capped prepolymers with resorcinol, 2,4-dihydroxybenzaldehyde or 1-(2,4-dihydroxyphenyl)-hexanone-(1). Chain extenders are differentiated from each other by the structure of the side chain attached to the resorcinol rings. Isocyanate-terminated prepolymers were obtained from poly(1,4-butylene adipate) diol and 4,4′-diphenylmethane diisocyanate. These polyurethane elastomers were characterized using Fourier transform infrared spectroscopy, thermo-gravimetric analysis, differential scanning calorimetry, and mechanical measurements. The effects of the chemical structure of resorcinol-derivative chain extenders on the properties of polyurethane elastomers were investigated. A significant increase in maximum stress–strain properties and in thermal stability was observed for the samples with free carbonyl in the side chain of the resorcinol ring. All the polymers showed 5% weight losses above 300 °C and glass transition temperature values in the range of −39 and −23 °C. The aim was to enhance the mechanical properties and thermal behavior by varying the chemical structure of the resorcinol moieties from the hard segment domain, without transform phenolic OH groups in aliphatic OH groups.