Kohári Andrea, Halász István Zoltán, Bárány Tamás
Department of Polymer Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Műegyetem rkp. 3., H-1111 Budapest, Hungary.
Polymers (Basel). 2019 Oct 12;11(10):1663. doi: 10.3390/polym11101663.
The aim of this paper was the detailed investigation of the properties of one-shot bulk polymerized thermoplastic polyurethanes (TPUs) produced with different processing temperatures and the properties of thermoplastic dynamic vulcanizates (TDVs) made by utilizing such in situ synthetized TPUs as their matrix polymer. We combined TPUs and conventional crosslinked rubbers in order to create TDVs by dynamic vulcanization in an internal mixer. The rubber phase was based on three different rubber types: acrylonitrile butadiene rubber (NBR), carboxylated acrylonitrile butadiene rubber (XNBR), and epoxidized natural rubber (ENR). Our goal was to investigate the effect of different processing conditions and material combinations on the properties of the resulting TDVs with the opportunity of improving the interfacial connection between the two phases by chemically bonding the crosslinked rubber phase to the TPU matrix. Therefore, the matrix TPU was synthesized in situ during compounding from diisocyanate, diol, and polyol in parallel with the dynamic vulcanization of the rubber mixture. The mechanical properties were examined by tensile and dynamical mechanical analysis (DMTA) tests. The morphology of the resulting TDVs was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM) and the thermal properties by differential scanning calorimetry (DSC). Based on these results, the initial temperature of 125 °C is the most suitable for the production of TDVs. Based on the atomic force micrographs, it can be assumed that phase separation occurred in the TPU matrix and we managed to evenly distribute the rubber phase in the TDVs. However, based on the SEM images, these dispersed rubber particles tended to agglomerate and form a quasi-continuous secondary phase where rubber particles were held together by secondary forces (dipole-dipole and hydrogen bonding) and can be broken up reversibly by heat and/or shear. In terms of mechanical properties, the TDVs we produced are on a par with commercially available TDVs with similar hardness.
本文旨在详细研究在不同加工温度下制备的一次性本体聚合热塑性聚氨酯（TPU）的性能，以及利用这种原位合成的TPU作为基体聚合物制备的热塑性动态硫化胶（TDV）的性能。我们将TPU与传统的交联橡胶相结合，以便通过在密炼机中进行动态硫化来制备TDV。橡胶相基于三种不同的橡胶类型：丙烯腈丁二烯橡胶（NBR）、羧基化丙烯腈丁二烯橡胶（XNBR）和环氧化天然橡胶（ENR）。我们的目标是研究不同加工条件和材料组合对所得TDV性能的影响，并有机会通过将交联橡胶相化学键合到TPU基体上来改善两相之间的界面连接。因此，在混炼过程中，基体TPU由二异氰酸酯、二醇和多元醇原位合成，同时橡胶混合物进行动态硫化。通过拉伸和动态力学分析（DMTA）试验检测力学性能。通过原子力显微镜（AFM）和扫描电子显微镜（SEM）研究所得TDV的形态，通过差示扫描量热法（DSC）研究热性能。基于这些结果，125℃的初始温度最适合TDV的生产。基于原子力显微镜图像，可以假设在TPU基体中发生了相分离，并且我们成功地在TDV中均匀分布了橡胶相。然而，基于SEM图像，这些分散的橡胶颗粒倾向于团聚并形成准连续的第二相，其中橡胶颗粒通过二次力（偶极 - 偶极和氢键）结合在一起，并且可以通过加热和/或剪切可逆地分解。在力学性能方面，我们生产的TDV与具有相似硬度的市售TDV相当。
