Elastomer-polymer blends for improving tire performance

这是一个材料化学博士研究项目。改善汽车和卡车轮胎性能的挑战是降低其滚动阻力，同时增加制动过程中的能量耗散。已知天然橡胶和合成橡胶与热塑性聚合物的共混可对轮胎性能具有深远影响。然而，先验分子水平的理解和观察到的机械性能变化的关系仍然没有很好地理解。因此，该项目的总体目标是了解模型轮胎化合物中聚合物-聚合物共混物的结构-性能关系。已知所观察到的性能增强是由分子动力学的变化主导的，但与共混物结构或连续介质力学的相关性还没有得到很好的理解。因此，本项目将首先合成模型丁苯弹性体和线性聚合物（控制MW和DPI）作为后续研究的基础，这些模型系统将用于研究聚合物对玻璃化转变温度（Tg）的影响，以及弹性体在共混物中的动力学和动力学不均匀性的温度依赖性。这些数据将与共混物的形态和链结构和机械性能，包括基本的变形性能，但也轮胎相关的滚动阻力，磨损和tribology.The主要技术，以确定在一个广泛的频率范围内的动态性能的指标将被研究的动态力学分析（DMA）结合准弹性中子散射（QENS）。结构研究，以评估共混物结构将利用光学和电子显微镜加上X射线和中子散射。这些技术将与其他分析技术包括DSC和GPC相结合。作为公司合作和支持的一部分，大陆轮胎（德国）的研究基地也将提供用于配混和轮胎测试的专业设备。

This is a PhD research project in materials chemistry.The challenge in improving car and truck tire performance is to reduce its rolling resistance, whilst simultaneously increasing energy dissipation during braking. It is known that blending of natural and synthetic rubbers with thermoplastic polymers can have profound effects on tire performance. However, a priori molecular level understanding and the relationship to the observed mechanical property changes are still not well understood. The overall aim of the project is therefore to understand structure-property relationships in elastomer-polymer blends in model tire compounds.The observed property enhancements are known to be dominated by changes in molecular dynamics, and yet the correlation to either the blend structure or the continuum mechanics is not well understood. This project will therefore initially synthesize model styrene-butadiene elastomer and linear polymers (controlled MW & DPI) as the basis of the subsequent studies.These model systems will be used to investigate the effect the polymers have on the glass transition temperature (Tg), and also temperature dependence of the dynamics and dynamic heterogeneity of the elastomers in blends. These data will be correlated with the blend morphology and chain structure and mechanical properties, including basic deformation performance, but also tire related metrics of roll resistance, wear and tribology.The primary techniques to determine the dynamic properties over a wide frequency regime will be studied by a combination of dynamic mechanical analysis (DMA) coupled with quasi-elastic neutron scattering (QENS). Structural studies to evaluate the blend structure will exploit optical and electron microscopy coupled with X-ray and neutron scattering. These techniques will be combined with other analytical techniques incl DSC and GPC. Specialist equipment for compounding and tire testing will also be accessed at the research base at Continental Tires (Germany) as part of the collaboration and support by the company.