以液化木材為基質聚胺基甲酸酯樹脂之反應性及熱性質

Reactivity and Thermal Properties of Liquefi ed Wood-based Polyurethane Resins

本研究將相思樹（Acacia confusa; Taiwan acacia）及杉木（Cunninghamia lanceolata; China fi r）木粉以聚乙二醇／丙三醇混合液為溶劑進行液化處理，所得液化木材進一步與Desmodur L或Desmodur N 兩種異氰酸酯混合製備聚胺基甲酸酯樹脂（Polyurethane; PU），並利用熱示差掃描卡量儀（Differential scanning calorimeter; DSC）以等溫模式探討液化木材與異氰酸酯之反應性，以動態熱掃描模式分析膠化PU樹脂之熱性質。由結果得知液化木材與Desmodur L間具備高反應性，與Desmodur N之反應性則較低，添加催化劑可有效促進其反應。以芳香族Desmodur L為原料之PU樹脂薄膜之玻璃轉移溫度較高，以脂肪族Desmodur N為原料者則較低。隨NCO/（OH+COOH）莫耳比增加，硬化PU樹脂之玻璃轉移現象向高溫偏移。常溫硬化之PU樹脂在加熱至約200℃時出現後硬化現象，NCO/（OH+COOH）莫耳比較大者，此後硬化之放熱峰較明顯。 Wood powders of Taiwan acacia (Acacia confusa) and China fi r (Cunninghamia lanceolata) were liquefied in the mixture of polythylene glycol/glycerol as a solvent. The liquefied woods were mixed with isocyanate, i.e. Desmodur L or Desmodur N, to prepare polyurethane (PU) resins. Differential scanning calorimeter (DSC) with isothermal mode was used to investigate the reactivity of liquefi ed wood with isocyanate, as well as dynamic thermal scanning mode was used to detect the thermal properties of cured resins. The results showed that the one of liquefied wood mixed with Desmodur L had higher reactivity than that with Desmodur N. However, adding catalyst could promote their reactivity. PU fi lms prepared with aromatic isocyanate (Desmodur L) had higher glass transition temperature than that with aliphatic isocyanate (Desmodur N). Increasing the molar ratio of NCO/(OH+COOH), the glass transition phenomenon of cured PU resins shifted to higher temperature. Room temperature cured PU resins had postcuring reaction at about 200℃. The higher isocyanate ratio the more obviously exothermal peak was.