本文關(guān)鍵詞： 詞:PBT PP SiC GF 熱性能　出處：《蘇州大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來(lái),聚合物基導(dǎo)熱絕緣復(fù)合材料在散熱領(lǐng)域發(fā)揮著越來(lái)越重要的作用,因?yàn)樯釂?wèn)題會(huì)直接影響元器件的穩(wěn)定性和使用壽命。相比于傳統(tǒng)導(dǎo)熱材料(金屬、陶瓷),聚合物基導(dǎo)熱復(fù)合材料具有質(zhì)量輕和易于加工設(shè)計(jì)的優(yōu)點(diǎn)。但是,純聚合物的導(dǎo)熱系數(shù)非常低,通常在0.1-0.5 W/m K范圍內(nèi),因此常使用導(dǎo)熱填料填充聚合物以克服聚合物的低導(dǎo)熱性缺點(diǎn)。本文中,首先采用玻纖增強(qiáng)PBT(PBT-20%GF)和不同含量的Si C通過(guò)熔融共混得到PBT/Si C復(fù)合材料。當(dāng)Si C填料的含量達(dá)到50 wt%時(shí),PBT/Si C復(fù)合材料的導(dǎo)熱系數(shù)僅為0.6145 W/m K,且在較高填充量時(shí),由于超細(xì)Si C顆粒比表面積大,顆粒間容易團(tuán)聚,這會(huì)導(dǎo)致復(fù)合材料的加工性能變差。加入適量的偶聯(lián)劑KH550可以在一定程度上改善PBT/Si C復(fù)合材料的導(dǎo)熱系數(shù),但提高幅度非常有限。為了進(jìn)一步提高復(fù)合材料的導(dǎo)熱性能和改善加工性能,在該導(dǎo)熱復(fù)合材料中引入第二相聚合物PP,使用玻纖增強(qiáng)PBT(PBT-20%GF),通過(guò)二步加工法制備PBT/PP/Si C復(fù)合材料,使填料分散在PBT相中,通過(guò)形成較理想的導(dǎo)熱填料分布,提高了填料在PBT相中的有效濃度,繼而進(jìn)一步提高了其導(dǎo)熱系數(shù)。研究了填料含量對(duì)復(fù)合材料PBT/PP/Si C的流變性能、微觀結(jié)構(gòu)、熱性能、力學(xué)性能和介電性能的影響。實(shí)驗(yàn)結(jié)果表明,PP形成分散相,PBT形成連續(xù)相,而Si C選擇性地分布在PBT相中。PBT/PP/Si C復(fù)合材料的導(dǎo)熱系數(shù)隨著碳化硅含量的增加而增加,當(dāng)碳化硅的填充量達(dá)到40 wt%時(shí),導(dǎo)熱系數(shù)為1.181 W/m K,是PBT/PP復(fù)合材料的近四倍。在相同的填充含量時(shí),PBT/PP/Si C復(fù)合材料的導(dǎo)熱系數(shù)比PBT/Si C復(fù)合材料的導(dǎo)熱系數(shù)高。由此可見(jiàn),第二相聚合物PP具有尺寸占據(jù)效應(yīng)以此提高了填料的有效濃度,PBT/PP/Si C復(fù)合材料的導(dǎo)熱系數(shù)隨之升高。另外,玻璃纖維材料具有較大的長(zhǎng)徑比,能有效地互相接觸而形成導(dǎo)熱網(wǎng)絡(luò),玻璃纖維與超細(xì)顆粒復(fù)合填充聚合物不僅能增大玻璃纖維與基體樹(shù)脂的接觸面積,還能有效地促進(jìn)顆粒的定向分布從而提高復(fù)合材料的導(dǎo)熱性能。因此本文還通過(guò)靜電復(fù)合技術(shù)在玻璃纖維表面包覆超細(xì)碳化硅顆粒,然后通過(guò)熔融共混法制備了PBT/GF-Si C復(fù)合材料,分別研究了填料含量對(duì)PBT/GF-Si C復(fù)合材料的微觀構(gòu)、熱性能、動(dòng)態(tài)力學(xué)性能和介電性能的影響。實(shí)驗(yàn)結(jié)果表明,經(jīng)過(guò)剪切作用之后,部分碳化硅顆粒仍包覆在玻璃纖維表面并且相互接觸,其它顆粒則從玻璃纖維表面脫落下來(lái),但仍分散在玻璃纖維周?chē)纬捎行Ф哑?在局部范圍內(nèi)增大填料濃度,從而形成有效的導(dǎo)熱通路。當(dāng)GF-Si C的含量為30 wt%時(shí),PBT/GF-Si C復(fù)合材料的導(dǎo)熱系數(shù)為0.6392 W/m K,約為PBT/GF/Si C復(fù)合材料的近兩倍,這也說(shuō)明對(duì)玻璃纖維表面預(yù)處理是有效果的。
[Abstract]:In recent years, polymer based thermal insulation composites play a more and more important role in the field of heat dissipation, because heat dissipation directly affects the stability and service life of components, compared with traditional thermal conductive materials (metals). Ceramic, polymer-based thermal conductivity composites have the advantages of light weight and easy to design. However, the thermal conductivity of pure polymers is very low, usually in the range of 0.1-0.5 W / m K. Therefore, thermal conductive fillers are often used to fill polymers to overcome the shortcomings of low thermal conductivity of polymers. First, glass fiber reinforced PBTT-20 is used. PBT/Si C composites were obtained by melt blending with different contents of sic, when the content of sic filler reached 50 wt%. The thermal conductivity of PBT/Si C composites is only 0.6145 W / m K, and the superfine sic particles are easy to agglomerate because of the large specific surface area of the superfine sic particles. The thermal conductivity of PBT/Si C composites can be improved to some extent by adding appropriate coupling agent KH550. In order to further improve the thermal conductivity and processability of the composites, the second phase polymer PP was introduced into the composites. The PBT/PP/Si C composites were prepared by using glass fiber reinforced PBT-20 / GFN method. The fillers were dispersed in the PBT phase. The effective concentration of filler in PBT phase was increased by forming an ideal distribution of thermal conductive filler. The rheological properties, microstructure and thermal properties of PBT/PP/Si C composites were studied. The influence of mechanical properties and dielectric properties. The experimental results show that PP forms dispersed phase and PBT forms continuous phase. However, the thermal conductivity of sic / PP / sic composites increased with the increase of sic content when the content of sic reached 40 wt%. The thermal conductivity is 1.181 W / m K, which is nearly four times of that of PBT/PP composites. The thermal conductivity of PBT/PP/Si C composites is higher than that of PBT/Si C composites. The second phase polymer PP has the size occupation effect to increase the effective concentration of filler and the thermal conductivity of PBT / PP / Si C composites. Glass fiber material has a large aspect ratio and can effectively contact with each other to form a thermal network. The composite polymer filled with glass fiber and ultrafine particles can not only increase the contact area between glass fiber and matrix resin. It can also effectively promote the directional distribution of particles and improve the thermal conductivity of composites. Therefore, this paper also coating ultrafine silicon carbide particles on glass fiber surface by electrostatic composite technology. Then, PBT/GF-Si C composites were prepared by melt blending method. The microstructure and thermal properties of PBT/GF-Si C composites with filler content were studied. The effect of dynamic mechanical properties and dielectric properties. The experimental results show that after shear, some sic particles are still coated on the surface of glass fiber and contact with each other. Other particles fell off the surface of the glass fiber, but still dispersed around the glass fiber to form an effective pile up, increasing the concentration of filler in the local range. When the content of GF-Si C is 30 wt%, the thermal conductivity of PBT / GF-Si C composite is 0.6392 W / m K. It is about twice as much as PBT/GF/Si C composite material, which also shows that the pretreatment of glass fiber surface is effective.
【學(xué)位授予單位】：蘇州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB332

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