聚氨酯的热敏特性与皮革透气、透湿性的研究  

Thermal-sensitive Polyurethane and the Water Vapor Permeability of Leather

作　　者：范浩军[1] 陈玲[1] 范新年[2] 石碧[1] 

机构地区：[1]皮革化学与工程教育部重点实验室(四川大学),四川成都610065 [2]四川大学化工学院,四川成都610065

出　　处：《皮革科学与工程》2005年第1期7-12,共6页Leather Science and Engineering

摘　　要：合成了三种不同结构的水基聚氨酯,其中PU(a)为一般无规结构的聚氨酯弹性体,PU(b)和 PU(c)为典型的嵌段结构。比较了三类不同结构的嵌段聚氨酯在相转变过程中构象熵、焓的变化以及温度对皮革透湿性的影响,结果表明:在相转变温度(开关温度)前后,聚合物的构象熵、焓、储能模量、损耗模量和损耗角正切等发生显著变化,表现出明显的热敏特性;由于分子链自由体积明显增大和分子热运动(微布朗运动)的加剧,嵌段聚氨酯 PU(b)、PU(c)薄膜的吸水率和薄膜的透湿率显著提高。当温度从25 ℃上升到35 ℃,PU(b)薄膜的透湿率由3800 g/m2.24h.atm上升到8730 g/m2.24h.atm,增幅率达到130%;对PU(c)薄膜,当温度从 45 ℃变化至 55 ℃时,其透湿率由4100 g/m2.24h.atm上升到11000 g/m2.24h.atm,增幅率达到 168%,而一般聚氨酯弹性体 PU(a)薄膜的透湿率在测试温度范围内仅发生微小的变化。革坯经三种聚氨酯涂饰后,其成革的透湿性也表现出了相似的热敏特性。利用聚合物相态的转变伴随着聚合物自由体积和微布朗运动的显著变化可望实现合成革和真皮革透气、透湿性的智能控制。Three types of water-based polyurethane, which one is an amorphous elastomer, and others are thermal sensitive segmental polyurethanes were synthesized and used for water vapor permeable leather finishing.Differential Scanning Calorimetry (DSC), Dynamic Mechanical thermal Analyzer (DMTA), water swell and water vapor permeability (WVP) were measured to evaluate how the structure of polyurethanes and temperature influence WVPs of PU films and finished leathers. In contrast to common polyurethane elastomer PU(a) with an amorphous reversible phase,the properties such as entropy, enthalpy, Storage modulus(E’),Loss modulus(E”) and Tanδof the segmental PU(c) with crystalline reversible phase and PU(b)with glass transition reversible phase show a great changes when the temperature covers the phase transition temperature (switch temperature). The water swell and water vapor permeability of both thermal sensitive segmental polyurethane films and finished leathers are found to depend on the inner structure of polymers and temperature. When the temperature exceeds the switch temperature,a significant increase of WVP from 3800 g/m^(2).day to 8730 g/m^(2).day for PU(b) film and from 4100 g/m^(2).24h.atm to 11000 g/m^(2).24h.atm for PU(c) film take place due to the enhanced Free Volume and micro-Brownian motion of macromolecular,the improvement of WVPs reach 130% and 168%, respectively. Study on WVP of finished leathers show a similar conclusion. Whereas both film and leather finished with PU(a) appear to a low WVP and a slight increased tendency in all temperature range. Phase transition accompanying a significant change of WVP resulting from enhanced Free Volume and micro-Brownian motion of macromolecular can be used to develop 'smart leather' with warm-insulation at cold temperature and high water vapor permeability at warm temperature.

关 键 词：热敏聚氨酯 涂饰 透气性 智能皮革 

分 类 号：TS529[轻工技术与工程—皮革化学与工程]