本文選題：高分子 + 高速外場��； 參考：《中國科學技術大學》2017年碩士論文

【摘要】：流動場誘導高分子是一種工業(yè)加工和物理科學中重要的研究課題。由于高分子鏈獨特的長鏈結構,具有較長的鏈松弛時間,可以通過高速宏觀外場對微觀結構進行調控。在很多加工過程和實際使用過程中,高分子往往處于高速外場當中,屬于熱力學非平衡態(tài)。在這種狀態(tài)下,由于鏈變形與松弛的相互競爭,不同結構在相變過程中熱力學穩(wěn)定性與動力學路徑的競爭就更加復雜。本文主要關注高速外場下誘導高分子結晶過程中的結晶形態(tài)、晶型和結晶動力學,研究結構的形成機理和動力學競爭關系。設計了與原位X射線高時間分辨散射聯(lián)用的外場施加設備,并利用這些設備對等規(guī)聚丙烯(iPP)及其他不同樣晶體系在不同實驗條件下的結晶過程進行了原位檢測。本文的主要結果如下:1)針對不同的外場條件和原位時間分辨X射線散射的檢測需求,設計了多種原位檢測實驗設備,包括:多段加速超高速拉伸流變儀、原位拉伸與可控淬火設備和高速蠕變拉伸流變儀并與寬角/小角X射線散射(SAXS/WAXS)原位檢測技術進行了原位測試;設計了一套新型的基于量子級聯(lián)激光器(QCL)的高速構象檢測系統(tǒng)。2)研究等規(guī)聚丙烯在不同溫度和應變速率下的拉伸誘導結晶結果及其演化規(guī)律。實驗發(fā)現(xiàn)在足夠強的流場下,即使熔點之上,α晶和β晶也可以同時生成;高溫和高應變速率下,β晶相對更加穩(wěn)定。根據(jù)實驗結果提出iPP的流動場誘導結晶非平衡相圖,研究非平衡條件下的高分子結晶行為。3)設計并構建了γ射線輻照形成的交聯(lián)iPP體系,研究這種交聯(lián)網絡-短鏈體系在拉伸條件下由于動力學不對稱性而產生的獨特的結晶動力學及晶體形態(tài)的變化。實驗發(fā)現(xiàn),在較大應變拉伸下,交聯(lián)iPP體系中的短鏈會被擠出,并發(fā)生松弛和解纏結,減慢結晶動力學。而交聯(lián)網絡不會發(fā)生松弛,晶體的取向度反而會連續(xù)增加。由體系松弛時間尺度的不對稱造成反常鏈響應行為能夠產生獨特的長程有序結構。本文的主要創(chuàng)新點如下:1)針對不同的檢測條件和檢測需求,設計了不同的高速外場原位檢測設備,并對不同的樣晶體系進行了原位觀測。2)提出了 iPP在溫度-應變速率空間的流動場誘導結晶非平衡相圖,研究了iPP在寬溫度和應變速率范圍下的動力學相變行為。3)利用交聯(lián)iPP體系作為多分散性高分子的一個極端體系,探討動力學不對稱在流動場誘導結晶中對于相變動力學和結構形態(tài)的影響。
[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.
【學位授予單位】：中國科學技術大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O632.12

【參考文獻】

相關期刊論文 前1條

1 Dong Liu;Kunpeng Cui;Ningdong Huang;Zhen Wang;Liangbin Li;;The thermodynamic properties of flow-induced precursor of polyethylene[J];Science China(Chemistry);2015年10期

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本文編號：2097545