ABSTRACT Polyurethane/Halloysite Nantubes nanocomposites containing 1 wt.% nanoparticles were prepared using in situ polymerization method with different mixing sequences. Various experiments have been performed in order to evaluate the effect of nanoparticle dispersion and the different orders of mixing of the samples on the mechanical properties and morphology of nanocomposites. The results obtained from the ATR-FTIR test demonstrated that the presence of nanoparticles led to an increase in phase separation, and the sample with the best nanoparticle dispersion has shown more phase separation than the other samples. Furthermore, the results of the Differential scanning calorimetry (DSC) also confirmed more phase separation and the crystallinity of the samples in the presence of nanoparticles. Scanning electron microscope (SEM) images were utilized in order to investigate the dispersion of nanoparticles in polyurethane matrix and to examine surface fracture of the samples. Moreover, differential mechanical thermal analysis (DMTA) revealed that the presence of nanoparticles has altered the glass transition temperature of polymers, and there are physical and chemical interaction and hydrogen bonding between nanoparticles and hard and soft polyurethane segments. In addition, in the presence of nanoparticles the damping of the samples was reduced compared to the neat sample. Change in behavior from liquid like to solid like in the range of low angular frequencies was observed which is in agreement with the formation of a network structure that can be broken even at low shear rates. In the second step, kinetics of the phase separation process of thermoplastic polyurethane and nanocomposites was studied by rheological experiments. The results showed that the kinetics of phase separation process of thermoplastic polyurethane is similar to that of the crystallization process. Phase separation kinetics of neat samples and nanocomposite have been studied. The presence of nanoparticles by nucleation mechanism increased the rate of the phase separation.

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进料顺序对含埃洛石纳米管聚氨酯纳米复合材料性能的影响

摘要 聚氨酯/埃洛石纳米管纳米复合材料含有 1 wt.% 纳米颗粒，采用原位聚合方法制备，混合顺序不同。为了评估纳米颗粒分散和样品的不同混合顺序对纳米复合材料的机械性能和形态的影响，已经进行了各种实验。从 ATR-FTIR 测试获得的结果表明，纳米粒子的存在导致相分离增加，并且具有最佳纳米粒子分散的样品比其他样品显示出更多的相分离。此外，差示扫描量热法 (DSC) 的结果也证实了在纳米颗粒存在下样品的更多相分离和结晶度。使用扫描电子显微镜 (SEM) 图像来研究纳米粒子在聚氨酯基质中的分散情况并检查样品的表面断裂。此外，差示机械热分析（DMTA）表明，纳米颗粒的存在改变了聚合物的玻璃化转变温度，纳米颗粒与聚氨酯硬段和软段之间存在物理和化学相互作用以及氢键。此外，与纯样品相比，在纳米颗粒的存在下，样品的阻尼降低。观察到在低角频率范围内从类似液体到类似固体的行为变化，这与即使在低剪切速率下也可以破裂的网络结构的形成一致。第二步，通过流变实验研究了热塑性聚氨酯和纳米复合材料的相分离过程的动力学。结果表明，热塑性聚氨酯的相分离过程动力学与结晶过程相似。已经研究了纯样品和纳米复合材料的相分离动力学。通过成核机制的纳米粒子的存在增加了相分离的速率。