超高分子量聚乙烯及其納米復(fù)合材料的鏈纏繞結(jié)構(gòu)調(diào)控
發(fā)布時間：2019-07-03 12:29
【摘要】：超高分子量聚乙烯(UHMWPE)是指分子量超過100萬g/mol的高密度聚乙烯。由于其制品具有其它材料無可比擬的耐沖性、耐磨性、自潤滑性和耐化學(xué)腐蝕等特性,目前已經(jīng)被廣泛的應(yīng)用于民用、軍用等各個領(lǐng)域。目前加工UHMWPE的常用方法主要有擠出成型法、模壓成型法和注塑成型法等方法。但是,由于商用的UHMWPE的分子量大、鏈纏結(jié)高,使得加工過程耗能巨大,且污染嚴(yán)重。于是,從根本上減少UHMWPE基體粉料的纏結(jié)度,從而降低加工難度,以期達(dá)到綠色加工的目的,是生產(chǎn)UHMWPE的重要研究方向。本論文基于“通過加入不同種類的多面齊聚倍半硅氧烷(Polyhedral oligomeric silsesquioxane,POSS)納米粒子,改變催化劑的聚合環(huán)境,從而構(gòu)建與活性中心特性相宜的鏈段生長環(huán)境”的研究思想,圍繞制備無纏結(jié)UHMWPE納米復(fù)合材料,進(jìn)行了如下四個方面的工作:(1)極性POSS粒子對UHMWPE鏈纏繞的調(diào)控;(2)非極性POSS粒子對UHMWPE鏈纏繞的調(diào)控;(3)極性POSS粒子對UHMWPE鏈段結(jié)晶行為的影響;(4)小分子聚合物對UHMWPE鏈纏繞的影響。具體的工作及主要研究成果如下:(1)通過化學(xué)負(fù)載將FI催化劑鉚釘在POSS上,從而改變的催化劑的聚合環(huán)境,并通過控制聚合時間得到了不同纏結(jié)狀態(tài)的UHMWPE納米復(fù)合材料。研究表明:FI催化劑通過化學(xué)負(fù)載的方式結(jié)合在POSS表面,且通過乙烯的原位聚合,POSS粒子能夠被均勻的分散在UHMWPE基體中。同時,我們得到了無纏結(jié)的UHMWPE納米復(fù)合材料。最后,POSS粒子能夠加強(qiáng)UHMWPE基體的熱穩(wěn)定性和吸水性。(2)通過物理負(fù)載,使不同種類的非極性烷基POSS調(diào)節(jié)FI催化劑的聚合環(huán)境,來達(dá)到調(diào)節(jié)UHMWPE纏結(jié)度的目的。研究表明:能夠在甲苯中完全分散的甲基-POSS在UHMWPE中獲得了最好的分散程度。通過結(jié)晶動力學(xué)和流變學(xué)的研究,我們可以知道環(huán)己基-POSS相對于甲基-POSS和苯基-POSS最能使UHMWPE基體趨于無纏結(jié)。(3)為了探明極性POSS影響UHMWPE鏈段纏結(jié)的機(jī)理,我們對具有相似分子量基體的UHMWPE的結(jié)晶行為進(jìn)行了研究。從等溫和非等溫結(jié)晶動力學(xué)研究中,我們看到:POSS在UHMWPE結(jié)晶過程中更多的扮演了成核劑的角色,由于POSS的加入可以增加UHMWPE鏈段結(jié)晶的速率,從而得到了無纏結(jié)的UHMWPE納米復(fù)合材料。(4)基于制備能夠合成雙峰聚乙烯的復(fù)合型催化劑,使得在聚合過程中使小分子聚合物原位的調(diào)節(jié)大分子量的UHMWPE的纏結(jié)程度。研究表明:我們制得了無纏結(jié)的UHWMPE復(fù)合材料,且當(dāng)聚合介質(zhì)為甲苯時,樣品最傾向于無纏結(jié)狀態(tài)。
[Abstract]:Ultra-high molecular weight polyethylene (UHMWPE) refers to high density polyethylene (HDPE) with a molecular weight of more than 1 million g / mol. Because of its unparalleled impact resistance, wear resistance, self-lubrication and chemical corrosion resistance, its products have been widely used in civil, military and other fields. At present, the common methods of processing UHMWPE are extrusion forming method, molding method and injection molding method. However, due to the large molecular weight and high chain entanglement of commercial UHMWPE, the processing process consumes a lot of energy and pollutes seriously. Therefore, it is an important research direction of UHMWPE production to fundamentally reduce the entanglement of UHMWPE matrix powder, so as to reduce the processing difficulty in order to achieve the purpose of green processing. Based on the research idea of "changing the polymerization environment of catalyst by adding different kinds of polyhedral oligomerized silsesquioxane (Polyhedral oligomeric silsesquioxane,POSS nanoparticles to construct the segment growth environment suitable for the characteristics of active center", the following four aspects of preparation of unentangled UHMWPE nanocomposites were carried out: (1) the regulation of polar POSS particles on UHMWPE chain winding; (2) the regulation of non-polar POSS particles on UHMWPE chain winding, (3) the effect of polar POSS particles on the crystallization behavior of UHMWPE segments, and (4) the effect of small molecular polymers on UHMWPE chain winding. The specific work and main research results are as follows: (1) the rivets of FI catalyst were loaded on POSS by chemical loading, thus changing the polymerization environment of the catalyst, and the UHMWPE nanocomposites with different entanglement states were obtained by controlling the polymerization time. The results show that the FI catalyst is bound to the POSS surface by chemical support, and the POSS particles can be uniformly dispersed in the UHMWPE matrix through the in-situ polymerization of ethylene. At the same time, we obtained UHMWPE nanocomposites without entanglement. Finally, POSS particles can enhance the thermal stability and water absorption of UHMWPE matrix. (2) different kinds of non-polar alkyl POSS can adjust the polymerization environment of FI catalyst by physical loading, so as to adjust the degree of UHMWPE entanglement. The results show that methyl-POSS, which can be completely dispersed in toluene, has the best dispersion degree in UHMWPE. Through the study of crystallization kinetics and Rheology, we can know that Cyclohexyl-POSS can make UHMWPE matrix tend to be unentangled compared with methyl-POSS and phenyl-POSS. (3) in order to find out the mechanism of polar POSS affecting UHMWPE segment entanglement, we have studied the crystallization behavior of UHMWPE with similar molecular weight matrix. From the study of Isomild non-Isothermal crystallization kinetics, we can see that POSS plays a more important role as nucleating agent in the crystallization process of UHMWPE. Because the addition of POSS can increase the crystallization rate of UHMWPE segment, the unentangled UHMWPE nanocomposites are obtained. (4) based on the preparation of composite catalysts which can synthesize bimodal polyethylene, In the process of polymerization, the small molecule polymer can adjust the entanglement degree of UHMWPE with large molecular weight in situ. The results show that the unentangled UHWMPE composites are prepared, and when the polymerization medium is toluene, the samples are most inclined to be unentangled.
【學(xué)位授予單位】：寧波大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O632.12;TB33
本文編號：2509384
[Abstract]:Ultra-high molecular weight polyethylene (UHMWPE) refers to high density polyethylene (HDPE) with a molecular weight of more than 1 million g / mol. Because of its unparalleled impact resistance, wear resistance, self-lubrication and chemical corrosion resistance, its products have been widely used in civil, military and other fields. At present, the common methods of processing UHMWPE are extrusion forming method, molding method and injection molding method. However, due to the large molecular weight and high chain entanglement of commercial UHMWPE, the processing process consumes a lot of energy and pollutes seriously. Therefore, it is an important research direction of UHMWPE production to fundamentally reduce the entanglement of UHMWPE matrix powder, so as to reduce the processing difficulty in order to achieve the purpose of green processing. Based on the research idea of "changing the polymerization environment of catalyst by adding different kinds of polyhedral oligomerized silsesquioxane (Polyhedral oligomeric silsesquioxane,POSS nanoparticles to construct the segment growth environment suitable for the characteristics of active center", the following four aspects of preparation of unentangled UHMWPE nanocomposites were carried out: (1) the regulation of polar POSS particles on UHMWPE chain winding; (2) the regulation of non-polar POSS particles on UHMWPE chain winding, (3) the effect of polar POSS particles on the crystallization behavior of UHMWPE segments, and (4) the effect of small molecular polymers on UHMWPE chain winding. The specific work and main research results are as follows: (1) the rivets of FI catalyst were loaded on POSS by chemical loading, thus changing the polymerization environment of the catalyst, and the UHMWPE nanocomposites with different entanglement states were obtained by controlling the polymerization time. The results show that the FI catalyst is bound to the POSS surface by chemical support, and the POSS particles can be uniformly dispersed in the UHMWPE matrix through the in-situ polymerization of ethylene. At the same time, we obtained UHMWPE nanocomposites without entanglement. Finally, POSS particles can enhance the thermal stability and water absorption of UHMWPE matrix. (2) different kinds of non-polar alkyl POSS can adjust the polymerization environment of FI catalyst by physical loading, so as to adjust the degree of UHMWPE entanglement. The results show that methyl-POSS, which can be completely dispersed in toluene, has the best dispersion degree in UHMWPE. Through the study of crystallization kinetics and Rheology, we can know that Cyclohexyl-POSS can make UHMWPE matrix tend to be unentangled compared with methyl-POSS and phenyl-POSS. (3) in order to find out the mechanism of polar POSS affecting UHMWPE segment entanglement, we have studied the crystallization behavior of UHMWPE with similar molecular weight matrix. From the study of Isomild non-Isothermal crystallization kinetics, we can see that POSS plays a more important role as nucleating agent in the crystallization process of UHMWPE. Because the addition of POSS can increase the crystallization rate of UHMWPE segment, the unentangled UHMWPE nanocomposites are obtained. (4) based on the preparation of composite catalysts which can synthesize bimodal polyethylene, In the process of polymerization, the small molecule polymer can adjust the entanglement degree of UHMWPE with large molecular weight in situ. The results show that the unentangled UHWMPE composites are prepared, and when the polymerization medium is toluene, the samples are most inclined to be unentangled.
【學(xué)位授予單位】：寧波大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O632.12;TB33
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 楊挺;程麗鴻;錢丹;;我國聚乙烯發(fā)展現(xiàn)狀及市場分析[J];絕緣材料;2013年03期
，本文編號：2509384
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