【摘要】：碳納米管(CNT)具有納米尺寸直徑、高長徑比、高強度同時又具有優(yōu)異的柔韌性以及良好的化學穩(wěn)定性,這使得CNT可以成為聚合物復合材料的理想填料,尤其在高性能納米復合材料領域應用前景誘人。然而由于范德華力相互作用使的CNT極難在熱塑性基體中形成穩(wěn)定分散,限制CNT發(fā)揮出本身的性能優(yōu)勢。本文主要采用熔融共混法制備CNT線性低密度聚乙烯(LLDPE)復合材料,通過研究CNT在LLDPE基體中分散工藝的優(yōu)化和易分散碳納米管母粒的制備和應用,為探索出一條CNT改性熱塑性抗靜電復合材料的產(chǎn)業(yè)化應用道路,進行了深入的研究,主要的研究內(nèi)容和創(chuàng)新點如下:1.首先采用熔融共混法制備不同CNT質(zhì)量分數(shù)的CNT/LLDPE復合材料,此時CNT/LLDPE復合材料的滲流閾值為3 wt%,彎曲強度達到最大值為6.32MPa,比純LLDPE基體提高28.78%,TEM表征可以看出CNT在LLDPE樹脂基體中分散較為均勻,CNT在LLDPE內(nèi)部相互搭接,構(gòu)建出有效的導電網(wǎng)絡。2.進一步研究了分散工藝對碳納米管改性線性低密度聚乙烯分散的影響,結(jié)果表明CNT填充量處于“敏感區(qū)”1?3 wt%時,直接熔融共混法比母粒稀釋法對CNT/LLDPE復合材料組建導電網(wǎng)絡效率更高;密煉工藝可以有效促進CNT在LLDPE基體中的分散,當填充3 wt%的CNT時,密煉工藝可以使得復合材料電阻率和表面阻抗都降低一個數(shù)量級;還優(yōu)選出表面分散劑為MPEG-2000,其添加量為5.0 wt%。3.基于上述研究,提出了一種易分散碳納米管母粒的制備方法,不僅可以減少CNT粉體的飛揚帶來的污染問題,還能縮短工藝流程,進一步降低成本。探索易分散碳納米管母粒在不同熱塑性基體中的分散性研究,對于LLDPE復合材料滲流閾值降低為1.5 wt%,相比其他兩種基體樹脂CNT在PET基體樹脂中分散效果最佳,滲流閾值最低。加工成型方式會影響復合材料電學性能,當CNT含量為3 wt%時,加工成型方式會導致CNT/LLDPE復合材料表面阻抗相差六個數(shù)量級。
[Abstract]:Carbon nanotube (CNT) has nanometer diameter, high aspect ratio, high strength, excellent flexibility and good chemical stability, which makes CNT an ideal filler for polymer composites. Especially in the field of high-performance nanocomposites applications are attractive. However, due to van der Waals interaction, it is very difficult for CNT to form stable dispersion in thermoplastic matrix, which limits the performance of CNT. In this paper, CNT linear low density polyethylene (LLDPE) (LLDPE) composites were prepared by melt blending method. The optimization of CNT dispersion process in LLDPE matrix and the preparation and application of easily dispersed carbon nanotube masterbatch were studied. In order to explore an industrial application road of CNT modified thermoplastic antistatic composites, the main research contents and innovations are as follows: 1. Firstly, CNT/LLDPE composites with different mass fraction of CNT were prepared by melt blending method. When the percolation threshold of CNT/LLDPE composites is 3 wt%, the maximum bending strength is 6.32 MPa, which is 28.78 MPA higher than that of pure LLDPE matrix. It can be seen that CNT is dispersed uniformly in the matrix of LLDPE resin and overlapped with each other in LLDPE, and an effective conductive network. 2. The effect of dispersion process on the dispersion of LLDPE modified by carbon nanotubes was further studied. The results showed that the filling amount of CNT was in the "sensitive zone" of 1 ~ 3 wt%. The direct melt blending method is more efficient than the masterbatch dilution method in the formation of conductive network of CNT/LLDPE composites, the mixing process can effectively promote the dispersion of CNT in the LLDPE matrix, and when the CNT is filled with 3 wt%, The surface resistance and surface impedance of composites can be reduced by one order of magnitude by densification process, and the surface dispersant is selected as MPEG-2000, and the addition amount is 5.0 wt%.3.. Based on the above research, a method of preparing easily dispersed carbon nanotube masterbatch is proposed, which can not only reduce the pollution caused by the flying of CNT powder, but also shorten the process flow and further reduce the cost. To explore the dispersion of easily dispersed carbon nanotube masterbatch in different thermoplastic matrix, the percolation threshold of LLDPE composite is reduced to 1.5 wt%,. Compared with other two kinds of matrix resin CNT, the dispersion effect of CNT in PET matrix resin is the best, and the percolation threshold is the lowest. When the content of CNT is 3 wt%, the surface impedance of CNT/LLDPE composites will differ by six orders of magnitude when the content of CNT is 3 wt%.
【學位授予單位】：合肥工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB332

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