高速流场诱导等规聚丙烯非平衡相变研究

发布时间：2018-07-04 21:40

本文选题：高分子 + 高速外场　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：流动场诱导高分子是一种工业加工和物理科学中重要的研究课题。由于高分子链独特的长链结构,具有较长的链松弛时间,可以通过高速宏观外场对微观结构进行调控。在很多加工过程和实际使用过程中,高分子往往处于高速外场当中,属于热力学非平衡态。在这种状态下,由于链变形与松弛的相互竞争,不同结构在相变过程中热力学稳定性与动力学路径的竞争就更加复杂。本文主要关注高速外场下诱导高分子结晶过程中的结晶形态、晶型和结晶动力学,研究结构的形成机理和动力学竞争关系。设计了与原位X射线高时间分辨散射联用的外场施加设备,并利用这些设备对等规聚丙烯(iPP)及其他不同样晶体系在不同实验条件下的结晶过程进行了原位检测。本文的主要结果如下:1)针对不同的外场条件和原位时间分辨X射线散射的检测需求,设计了多种原位检测实验设备,包括:多段加速超高速拉伸流变仪、原位拉伸与可控淬火设备和高速蠕变拉伸流变仪并与宽角/小角X射线散射(SAXS/WAXS)原位检测技术进行了原位测试;设计了一套新型的基于量子级联激光器(QCL)的高速构象检测系统。2)研究等规聚丙烯在不同温度和应变速率下的拉伸诱导结晶结果及其演化规律。实验发现在足够强的流场下,即使熔点之上,α晶和β晶也可以同时生成;高温和高应变速率下,β晶相对更加稳定。根据实验结果提出iPP的流动场诱导结晶非平衡相图,研究非平衡条件下的高分子结晶行为。3)设计并构建了γ射线辐照形成的交联iPP体系,研究这种交联网络-短链体系在拉伸条件下由于动力学不对称性而产生的独特的结晶动力学及晶体形态的变化。实验发现,在较大应变拉伸下,交联iPP体系中的短链会被挤出,并发生松弛和解缠结,减慢结晶动力学。而交联网络不会发生松弛,晶体的取向度反而会连续增加。由体系松弛时间尺度的不对称造成反常链响应行为能够产生独特的长程有序结构。本文的主要创新点如下:1)针对不同的检测条件和检测需求,设计了不同的高速外场原位检测设备,并对不同的样晶体系进行了原位观测。2)提出了 iPP在温度-应变速率空间的流动场诱导结晶非平衡相图,研究了iPP在宽温度和应变速率范围下的动力学相变行为。3)利用交联iPP体系作为多分散性高分子的一个极端体系,探讨动力学不对称在流动场诱导结晶中对于相变动力学和结构形态的影响。
[Abstract]:The flow field induced polymer is an important research topic in industrial processing and physical science. Due to the long chain relaxation time of the unique long chain structure of the polymer chain, the microstructure can be controlled by the high speed macro field. In the process of processing and actual use, the polymer is often in the high speed field. In this state, in this state, the competition between the thermodynamic stability and the dynamic path of the different structures is more complex in the process of phase transition due to the competition between the chain deformation and relaxation. This paper mainly focuses on the crystallization, crystal and crystallization kinetics of the high polymer crystallization process. The formation mechanism and the dynamic competitive relationship are designed. The external field application equipment with high time resolved scattering of X ray in situ is designed, and the crystallization process of iPP and other different crystal systems under the different experimental conditions is detected in situ. The main results of this paper are as follows: 1) for different external fields A variety of in-situ testing equipment, including multi section accelerated ultra high speed stretching rheometer, in situ tensile and controllable quenching equipment and high speed creep tensile rheometer, and in situ testing with wide angle / small angle X ray scattering (SAXS/WAXS) in situ testing, are designed and a set of in situ test is designed. A new type of high speed conformation detection system based on quantum cascade laser (QCL).2) is used to study the tensile induced crystallization of isotactic polypropylene at different temperatures and strain rates. The experimental results show that the alpha and beta crystals can be generated at the same time in the strong flow field even on the melting point; at high temperature and high strain rate, beta crystal phase is at high temperature and high strain rate. It is more stable. According to the experimental results, the non equilibrium phase diagram of the induced crystallization of iPP in the flow field is proposed and the crystallization behavior of polymer.3 under the non equilibrium condition is studied. The cross-linked iPP system formed by gamma ray irradiation is designed and the unique junction produced by the dynamic asymmetry of the crosslinked network short chain system under the tensile condition is studied. It is found that the short chain in the crosslinked iPP system will be extruded under the large strain tension, and the relaxation conciliation and entanglement will occur and the crystallization kinetics are slowed down. The crosslinking network will not relax and the degree of crystal orientation will increase continuously. The asymmetric chain response is caused by the asymmetry of the relaxation time scale of the body system. The main innovations of this paper are as follows: 1) according to the different detection conditions and detection requirements, different high speed field in-situ detection devices are designed, and the in-situ observation.2 of different crystal systems is carried out. The non equilibrium phase induced by iPP in the flow field of temperature stress rate space is proposed. The dynamic phase transition behavior (.3) of iPP at wide temperature and strain rate was studied. The cross linked iPP system was used as an extreme system of polydispersity polymer, and the effect of dynamic asymmetry on the phase transition kinetics and structure morphology in the induced crystallization of the flow field was investigated.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O632.12

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