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以聚醚多元醇、丁二醇和甲苯二异氰酸酯为原料 ,在不同起始反应温度下 (不用催化剂 )合成了一系列硬段含量为 30 %的聚氨酯弹性体 (PU) ,它们的起始反应温度分别为 2 0℃ (S -1 )、40℃ (S -2 )、6 0℃ (S -3)和 80℃ (S -4 )。用示差扫描量热分析、傅立叶变换红外光谱和透射电镜研究了它们的形态结构。研究结果发现 :随着初始反应温度的升高 ,试样S -1的相分离程度较大 ,S -2次之 ,S -3的相分离程度较小 ,但S-4的相分离程度又有升高的趋势 ,这可能是在合成过程中物料粘度以及网络结构的形成与硬段聚集成微区的速度不同所造成。用正电子湮没寿命谱研究了PU的自由体积特性 ,发现S -3的自由体积孔穴最小 ,相对自由体积浓度最高 ,但相对自由体积分数最低。进一步研究表明 ,S -3的电阻率也最高。由此可见 ,PU的形态结构与自由体积特性和材料的电性能密切相关。
Polyether polyols, butylene glycol and tolylene diisocyanate were used as starting materials to synthesize a series of polyurethane elastomers (PU) with hard segment content of 30% at different starting reaction temperature (without catalyst). Their initial reaction temperature Respectively, at 20 ° C (S -1), 40 ° C (S -2), 60 ° C (S -3) and 80 ° C (S -4). Differential scanning calorimetry, Fourier transform infrared spectroscopy and transmission electron microscopy of their morphological structure. The results show that phase separation of S-1 is larger with the increase of initial reaction temperature, S-2 followed by S-3. However, the degree of S-4 phase separation is smaller There is an increasing trend, which may be caused by the material viscosity and the formation of network structure in the synthesis process and the speed at which the hard segments are aggregated into microdomains. The positron annihilation life spectrum was used to study the free volume of PU. S-3 was found to have the smallest free volume and the highest relative free volume but the lowest relative free volume. Further studies have shown that S-3 also has the highest resistivity. Thus, the morphological structure of PU is closely related to the free volume characteristics and electrical properties of the material.