液化木材を基材としたポリウレタンの物性に及ぼすハードセグメント濃度の影響 Effects of Hard Segment Content on the Properties of Liquefied Wood based Polyurethanes
Effects of hard segment content on the mechanical and thermal properties of liquefied wood (LW) based polyurethanes (PUs) were studied. LW was prepared from Hinoki cypress (<i>Chamaecyparis obtusa</i>) wood meal using poly (oxyethylene) glycol as a liquefaction solvent. PUs with various hard segment content were prepared from LW as a polyol, polymeric diphenyl methane diisocyanate (pMDI) or hexamethylene diisocyanate (HDI) and 1, 4-butanediol using a one-shot method in bulk state. Gel fraction of pMDI based PUs exceeded over 94%, while that of HDI based PUs was about 43-46%. Glass transition temperature (<i>T</i><sub>g</sub>) and peak temperature of loss tangent (<i>T</i><sub>α</sub>) of pMDI based PUs drastically increased with increasing hard segment content. However, <i>T</i><sub>g</sub> and <i>T</i><sub>α</sub> of HDI based PUs increased slightly. These results suggest that pMDI based PUs had microphase mixing, but HDI based PUs had microphase separation. The degradation initiation temperature (<i>T</i><sub>s</sub>) of HDI based PUs increased with increasing hard segment content. However, there was no clear relation between <i>T</i><sub>s</sub> of pMDI based PUs and hard segment content. Tensile strength and Young's modulus of PUs increased with increasing hard segment content, respectively. Elongation at break of PUs decreased with increasing hard segment content.
日本ゴム協會誌 81(8), 339-345, 2008-08-15
THE SOCIRETY OF RUBBER SCIENCE AND TECHNOLOGYY, JAPAN