Thermal and Mechanical Properties of Polyurethanes Derived from Mono- and Disaccharides

Abstract

Department of Polymer Technology, Royal Institute of Technology, S-100 44 Stockholm, Sweden(Received 1 February 1996; revised version received 3 April 1996; accepted 8 July 1996)Abstract: Thermal and mechanical properties of polyurethane (PU) sheets pre-pared from the glucose/fructose/sucroseEpolyethylene glycol (PEG)Ediphenylmethane diisocyanate (MDI) system were examined by di†erential scan-ning calorimetry, thermogravimetry, dynamic mechanical analysis and tensiletests. The saccharide content was varied at a constant NCO : OH ratio of 1E0.The glass transition temperature increased with increasing saccharide(Tg)content. The incorporation of saccharides into the PU structure results in ahigher crosslinking density and a higher content of hard segments. The thermaldecomposition was dependent on the saccharide content, an increase leading to alower thermal decomposition temperature The dissociation of saccharide(Td).OH groups and NCO groups is a major part of the thermal decomposition ofthese PUs. Dynamic mechanical analysis revealed two kinds of relaxation: thehigh temperature relaxation corresponds to main chain motion and the other is alocal mode relaxation due to non-reacted isocyanate groups. The tensile stressand YoungIs modulus increased with the saccharide content.Key words: Polyurethane, mono- and di-saccharide, decomposition, glass tran-sition, DMA, tensile properties.* To whom all correspondence should be addressed¤ IRC in Polymer Science and Technology, University of Bradford, Bradford, BD7 1DP, UK.