本文關(guān)鍵詞： 聚乳酸共混物 碳納米管 選擇性分布 形態(tài)結(jié)構(gòu) 電學性能 形狀記憶行為　出處：《西南交通大學》2015年碩士論文　論文類型：學位論文

【摘要】：近些年來,納米復合材料以其優(yōu)異的綜合性能受到了研究者的廣泛關(guān)注。其中,碳納米管(Carbon nanotubes, CNTs)因其較大的長徑比、極高的強度和模量、優(yōu)異的導電和導熱性能而被廣泛地應(yīng)用于聚合物改性技術(shù)中,成為納米復合材料領(lǐng)域研究的熱點。對于只含有單一聚合物的CNTs納米復合材料而言,雖然CNTs的引入能在一定程度上改善聚合物的綜合性能,但改善效果有限,而且所需CNTs的含量較大,成本較高,無法滿足人們的日益增長的使用需求。因此,開發(fā)新型的基于聚合物共混物的CNTs填充改性納米復合材料勢在必行。對于含CNTs的聚合物共混納米復合材料而言,其性能除了依賴于共混物各個組分的本身性質(zhì)之外,還在很大程度上受到共混物形態(tài)結(jié)構(gòu)及CNTs選擇性分布的影響。本論文通過向聚乳酸(Poly(L-lactic acid), PLLA)基共混物中引入CNTs,采用簡單的熔融共混制備得到功能性共混納米復合材料。旨在通過CNTs的引入,研究CNTs在不相容共混物中的選擇性分布對電性能的影響；并且通過對熔融加工條件的調(diào)控,研究CNTs對共混復合材料形態(tài)演化的作用機制；另外,通過調(diào)控共混復合材料形態(tài)結(jié)構(gòu)及CNTs選擇性分布,研究CNTs的網(wǎng)絡(luò)結(jié)構(gòu)對共混納米復合材料的形狀記憶行為的影響。得到主要結(jié)果如下：(1)通過熔融共混的方法成功制備PLLA接枝馬來酸酐(PLLA grafted maleic anhydride, PLLA-g-MA)。在PLLA-g-MA分子極性和粘度的共同作用下,CNTs分布在PLLA-g-MA和高密度聚乙烯(Polyethyene, HDPE)兩相界面上；樣品得到較低的導電逾滲閡值(0.49 wt%)。同時觀察樣品形貌發(fā)現(xiàn),CNTs的引入加速了共混復合材料形態(tài)發(fā)展進程。(2)分別選取三個不同的共混時間點及剪切強度作為共混條件變量,制備得到PLLA-g-MA/HDPE共混物及PLLA-g-MA/HDPE/CNTs共混復合材料。形貌觀察及流變分析表明,無論在不同共混時間下還是不同剪切強度下,CNTs均加速了共混復合材料的形態(tài)發(fā)展進程。這是由于CNTs的存在一方面使體系粘度增加,局部剪切應(yīng)力增大,加速分散相粒子變形、破裂的過程；另一方面,CNTs在界面上的選擇性分布阻礙了分散相粒子的融合,使分散相具有較小的尺寸。導電性能測試表明,當共混時間為6 min,轉(zhuǎn)速為60 rpm時,所制備的共混復合材料的導電性能最好。(3)以熱塑性聚氨酯(Thermoplastic polyurethane, TPU)為母料,通過兩步法熔融共混制備得到PLLA/TPU/CNTs共混復合材料。微觀結(jié)構(gòu)表征發(fā)現(xiàn),CNTs分布在TPU中,且由于CNTs的填充作用,TPU相尺寸隨CNTs含量增加而逐漸變大。不同溫度下的熱致形狀回復行為表明,CNTs阻礙共混復合材料的熱致回復行為,且CNTs含量越高,這種阻礙作用越明顯。分析認為,這是由于CNTs的網(wǎng)絡(luò)結(jié)構(gòu)抑制了TPU分子鏈運動,阻礙其形狀回復過程。相反地,隨著CNTs含量的增多,共混復合材料的電致回復行為變得更明顯。無論熱致回復記憶行為還是電致形狀記憶行為,溫度的升高都有利于材料的形狀回復過程。
[Abstract]:In recent years, nano composite materials for their excellent properties has attracted much attention of researchers. Among them, carbon nanotubes (Carbon, nanotubes, CNTs) because of its high aspect ratio, high strength and modulus, excellent electrical conductivity and thermal conductivity have been widely used in polymer modification technology, has become a hot spot the research field of nano composite materials. The CNTs nano composite material contains only a single polymer, although the introduction of CNTs can improve the comprehensive performance of the polymer to a certain extent, but the improvement is limited, but also required the content of CNTs is large, high cost, unable to meet the growing needs. Therefore, the development of new the polymer blends based on CNTs filled imperative nano composite material. For polymer nanocomposites containing CNTs, but its performance depends on the blend In addition to a component of nature, are greatly affected by the blend morphology and CNTs selective distribution. This paper through to polylactic acid (Poly (L-lactic acid), PLLA) introduced CNTs based blends by melt blending process, simple preparation of functional blend nanocomposites. Designed by CNTs the introduction of CNTs in incompatible blends in the distribution of selective effects on the electrical performance; and through the regulation of melt processing conditions, effects of CNTs on the mechanism of the evolution of composite morphology; in addition, by regulating the blend morphology and CNTs selective distribution, influence of shape memory behavior of the network structure of CNTs the blending nano composite material. The main results are as follows: (1) preparation of PLLA grafted with maleic anhydride by melt blending method for grafted maleic (PLLA anhydride, P LLA-g-MA). Interaction between PLLA-g-MA molecular polarity and viscosity, the distribution of CNTs in PLLA-g-MA and high density polyethylene (Polyethyene, HDPE) interface; samples get lower conductive threshold (0.49 wt%). At the same time to observe the morphology of the samples showed that the introduction of CNTs accelerated the development of morphology of blends and composites (2) three. The process of blending different time and shear strength were selected as blending condition variables, the prepared PLLA-g-MA/HDPE blends and PLLA-g-MA/HDPE/CNTs composites. Morphology and rheological analysis showed that no matter in different time or different blends under shear strength, CNTs accelerate the development process of the morphology of blends and composites this is due to the presence of CNTs. On the one hand, the viscosity of the system increased, the local shear stress increases, accelerated particles deformation and rupture process; on the other hand, the CNTs in the interface The fusion of the selective distribution of hindered particles, the dispersed phase has a smaller size. The conductive performance tests show that when the mixing time is 6 min, the speed is 60 rpm, the conductive properties of prepared composites prepared by the best. (3) with thermoplastic polyurethane (Thermoplastic polyurethane, TPU) for the two step of melt blending masterbatch was prepared by blending PLLA/TPU/CNTs composite material. The characterization of the microstructure, the distribution of CNTs in TPU, and because the filling effect of CNTs, the size of TPU phase increased with the increase of CNTs content. The different temperature of thermally induced shape recovery behavior showed that the recovery behavior of CNTs blend composite caused by obstacles the heat, the higher the content of CNTs, the blocking effect is more obvious. The analysis thinks, this is because the network structure of CNTs inhibited TPU molecular chain movement, hinder the shape recovery process. On the contrary, with the increase of CNTs content, The electrical recovery behavior of the composites is more obvious. No matter the thermal recovery memory behavior or the electrical shape memory behavior, the increase of temperature is beneficial to the shape recovery process of the composites.

【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB332;O613.71

【引證文獻】

相關(guān)會議論文 前1條

1 鄒發(fā)生;董俠;劉偉;王篤金;韓志超;;小振幅振蕩剪切下PB/LPI共混物的形態(tài)與流變學研究[A];2012年全國高分子材料科學與工程研討會學術(shù)論文集（上冊）[C];2012年

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本文編號：1551230