本文選題：導(dǎo)電聚合物復(fù)合材料 + 電磁屏蔽��； 參考：《中北大學(xué)》2017年碩士論文

【摘要】：隨著電子科技及信息技術(shù)等領(lǐng)域的飛速發(fā)展,導(dǎo)電聚合物復(fù)合材料在功能材料中占有舉足輕重的位置。該類復(fù)合材料加工性能好、電阻可調(diào)節(jié)、成本低、可設(shè)計性強,廣泛應(yīng)用在能源、運輸、電子電器等領(lǐng)域。探索新方法制備具有高性能低成本的導(dǎo)電聚合物復(fù)合材料以及實現(xiàn)其在電磁屏蔽領(lǐng)域的應(yīng)用是目前導(dǎo)電功能材料領(lǐng)域尤為重要的研究課題。本課題通過碳纖維、膨脹石墨兩種導(dǎo)電填料對尼龍6進行改性,并通過對導(dǎo)電網(wǎng)絡(luò)結(jié)構(gòu)進行控制,得到了性能優(yōu)異的尼龍6導(dǎo)電復(fù)合材料。主要研究結(jié)果如下:(1)通過簡單熔融共混制備了PA6/EG復(fù)合材料,隨著熱膨脹石墨的加入,導(dǎo)電粒子之間形成的導(dǎo)電、導(dǎo)熱網(wǎng)絡(luò)越來越完善,得到了一種擁有優(yōu)異導(dǎo)電、導(dǎo)熱以及電磁屏蔽性能的復(fù)合材料。當(dāng)添加9.09vol%EG時材料的電導(dǎo)率達到0.262S/m,其導(dǎo)熱系數(shù)也達到最佳,為1.0202W/m·K,電磁屏蔽性能達到23dB。同時,EG的加入可以為復(fù)合材料提供更多的異相成核點,提高了復(fù)合材料的結(jié)晶溫度與結(jié)晶度,結(jié)晶度最高提高了26.98%。因此PA6/EG復(fù)合材料的動態(tài)儲能模量大幅度提高,并且填料的加入對聚合物分子鏈有限制作用,復(fù)合材料的玻璃化轉(zhuǎn)變溫度也大幅度提高。(2)通過在PA6和EG熔融共混過程中加入CF,改變兩種填料的比例制備了復(fù)合材料,結(jié)果表明CF對復(fù)合材料的增強作用特別明顯,相比純PA6,復(fù)合材料的拉伸、彎曲性能均有大幅提高。當(dāng)CF的質(zhì)量分數(shù)為20%時,PA6/EG/CF復(fù)合材料拉伸強度、拉伸模量、彎曲強度、彎曲模量最佳,可達到100.8 MPa,4.67 GPa和95.7 MPa和6.42 GPa,相比純PA6分別提高了41.69%、81.01%和86.55%,293.87%。EG的加入有利于復(fù)合材料導(dǎo)電、導(dǎo)熱以及電磁屏蔽性能的提高。添加20wt%EG時材料的電導(dǎo)率最高,達到0.262S/m,導(dǎo)熱系數(shù)可達1.3379W/m?K,電磁屏蔽性能也可達到20dB的應(yīng)用要求。并且EG和CF粒子在尼龍6基體中有異相成核作用,晶核生長速率增加,結(jié)晶更加容易,從而提高尼龍6復(fù)合材料的結(jié)晶溫度。并且隨著EG比例增加,結(jié)晶度先增大后減小。(3)通過高速機械共混-模壓成型制備了EG、CF兩種不同填料的隔離結(jié)構(gòu)PA6復(fù)合材料,其導(dǎo)電逾滲值明顯降低,達到了我們預(yù)期想要的結(jié)果。PA6/EG體系的逾滲值為0.134 vol%,PA6/CF體系的逾滲值為1.9 vol%。并且當(dāng)填料含量增加時,在復(fù)合材料中構(gòu)建了完善的導(dǎo)電網(wǎng)絡(luò),使得復(fù)合材料在導(dǎo)熱、電磁屏蔽、動態(tài)力學(xué)等方面也得到優(yōu)異的性能。并且對于隔離結(jié)構(gòu)PA6/CF復(fù)合材料來說,復(fù)合材料的屏蔽效能在8.2~12.4 GHz范圍內(nèi)的都是隨著頻率的增大先上升,出現(xiàn)特征峰值后又下降。且隨著CF含量的增大,特征吸收峰值不斷增大。并且隨著CF含量的增加出現(xiàn)特征峰的頻率向高頻移動。(4)通過在隔離結(jié)構(gòu)PA6/EG復(fù)合材料制備過程中添加一定量的CF制備的串聯(lián)隔離結(jié)構(gòu)的PA6/EG/CF復(fù)合材料,微觀結(jié)構(gòu)可以看出CF作為EG隔離導(dǎo)電網(wǎng)絡(luò)的橋梁,使得導(dǎo)電網(wǎng)絡(luò)更加完善,形成了一種類似“糖葫蘆”狀的結(jié)構(gòu)。對比了三種長度的CF制備的串聯(lián)隔離結(jié)構(gòu)PA6/EG/CF復(fù)合材料的導(dǎo)電、電磁屏蔽、動態(tài)力學(xué)等方面性能發(fā)現(xiàn),這三種長度的CF制備的復(fù)合材料的逾滲值分別為0.31 vol%、0.325 vol%、0.241vol%。通過100μm碳纖維制備的這種復(fù)合材料的各方面性能最優(yōu),5mm碳纖維制備次之,700μm碳纖維制備相對較低。
[Abstract]:With the rapid development of electronic technology, information technology and other fields, conductive polymer composites occupy an important position in functional materials. This kind of composite has good processing performance, adjustable resistance, low cost and strong design. It is widely used in the fields of energy, transportation, electrical appliances and so on. The new method has high performance and low performance. The cost of conductive polymer composite and its application in the field of electromagnetic shielding are the most important research topics in the field of conductive functional materials. This topic is modified by two kinds of conductive filler of carbon fiber and expanded graphite, and through the control of the structure of the conductive network, the nylon 6 with excellent performance is obtained. The main research results are as follows: (1) PA6/EG composites are prepared by simple melting and blending. With the addition of thermal expanded graphite, the conduction between conductive particles and the heat conduction network are becoming more and more perfect. A composite material with excellent conductivity, heat conduction and electrical and magnetic shielding properties is obtained. When 9.09vol%EG is added, the material is added to the material. The conductivity reaches 0.262S/m, its thermal conductivity is also the best, it is 1.0202W/m K, the electromagnetic shielding performance reaches 23dB.. The addition of EG can provide more heterogeneous nucleation points for the composite materials, improve the crystallization temperature and crystallinity of the composites, and the highest crystallinity increases the dynamic storage modulus of 26.98%. and thus the PA6/EG composite. The addition of the filler has a limited effect on the polymer molecular chain and the glass transition temperature of the composite increases greatly. (2) the composite is prepared by adding CF in the melt blending process of PA6 and EG and changing the proportion of two kinds of filler. The results show that the enhancement of the composites is particularly obvious, compared with pure PA6, When the mass fraction of CF is 20%, the tensile strength, tensile modulus, bending strength and flexural modulus of PA6/EG/CF composites are the best, which can reach 100.8 MPa, 4.67 GPa and 95.7 MPa and 6.42 GPa, compared with pure PA6 by 41.69%, 81.01% and 86.55% respectively. The addition of 293.87%.EG is beneficial to the composite. The electrical conductivity, heat conduction and electromagnetic shielding performance of the material are improved. When adding 20wt%EG, the material has the highest electrical conductivity, up to 0.262S/m, the thermal conductivity can reach 1.3379W/m? K, the electromagnetic shielding performance can also reach the application requirements of 20dB. And EG and CF particles have heterogenous nucleation in the nylon 6 matrix, the growth rate of crystal nucleus is increased, and the crystallization is easier. Thus, crystallization is more easy to extract and thus extract The crystallization temperature of the high nylon 6 composite was increased and the crystallinity increased first and then decreased with the increase of EG ratio. (3) the isolated structure PA6 composites of two different fillers were prepared by high speed mechanical blending and molding, and the percolation value of the.PA6/EG system decreased significantly, and the percolation value of the.PA6/EG system we expected was 0.134 Vo L%, the percolation value of the PA6/CF system is 1.9 vol%. and when the filler content is increased, a perfect conductive network is constructed in the composite material, which makes the composite excellent performance in heat conduction, electromagnetic shielding, dynamic mechanics and so on. And for the isolation structure PA6/CF composite material, the shielding effectiveness of the composite material is 8.2~12.4 GHz With the increase of the CF content, the peak value of the characteristic absorption increases with the increase of the content of the CF. (4) a certain amount of CF in series is added to the isolation structure of the PA6/EG composite material. The microstructure of PA6/EG/CF composite material, the microstructure can be seen as a bridge of CF as the EG insulation network, making the conductive network more perfect, forming a kind of "sugar gourd" like structure. Compare the conductivity, electromagnetic shielding, dynamic mechanics, and other aspects of the series isolated structure PA6/EG/CF composite prepared by three kinds of CF It is found that the percolation values of these three CF composites are 0.31 vol% and 0.325 vol% respectively. The properties of the composites prepared by 0.241vol%. by 100 mu m fiber are the best, the 5mm carbon fibers are prepared second, and the 700 um m carbon fiber is relatively low.

【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB332

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