發(fā)布時間：2018-06-26 20:35

  本文選題：PA6 + Al_2O_3　； 參考：《合肥工業(yè)大學》2015年碩士論文

【摘要】：導熱絕緣高分子復合材料的開發(fā)是解決當前電子電器和LED燈具散熱的重要課題。基于很多文獻報道的導熱絕緣復合材料的力學性能或者熱導率不能滿足某些高要求場合的使用,本文以PA6為基體,Al2O3為導熱填料,采用雙螺桿擠出機制備了導熱絕緣復合材料。研究了Al2O3添加量和粒徑對復合材料的性能影響。結(jié)果表明：復合材料熱導率均隨著Al2O3添加量的增加而增大,但力學性能下降；Al2O3的填充量相同時,Al2O3粒徑越大,PA6/Al2O3導熱絕緣復合材料熱導率越高,力學性能越差。當Al2O3添加量為70 wt%時,4μm、6μm、15μm和40μm Al2O3填充PA6復合材料的熱導率分別為1.213 W/(m·K), 1.268 W/(m·K),1.289 W/(m·K)和1.455 W/(m·K),而拉伸強度分別只有57.37MPa、53.77 Npa、52.12 MPa和49.5 MPa。為了改善復合材料的力學性能,本文以甲乙酮肟和異氰酸酯為原料,制備了一種封閉異氰酸酯硅烷,該物質(zhì)用作偶聯(lián)劑對Al2O3進行表面改性,研究了該偶聯(lián)劑對PA6/Al2O3復合材料的性能影響。SEM結(jié)果表明該封閉異氰酸酯硅烷可以改善Al2O3在基體中分散,增強與基體的連接性;平衡扭矩和力學性能結(jié)果表明該封閉異氰酸酯硅烷在復合材料熔融加工過程中解封,與PA6鏈端氨基或羧基發(fā)生原位反應,起到擴鏈劑的作用,改善了復合材料的力學性能；封閉異氰酸酯硅烷改性Al2O3/PA6復合材料的熱導率也較未改性有所提升。當Al2O3的添加量增加到70 wt%時,拉伸強度達到85.16 MPa,超過純PA6的拉伸強度；熱導率達到1.18 W/m·K,是PA6熱導率的3.83倍。綜合考慮復合材料的力學性能、熱導率和加工性能,將導熱填料的填充量確定為60 wt%,但該填充量下復合材料的熱導率較低。為了提高熱導率,本文采用大小粒徑Al2O3按不同的比例復配對PA6進行填充,結(jié)果表明6μm和40μm Al2O3按質(zhì)量比1：1復配時復合材料的性能最佳。為了進一步提高熱導率,我們采用上述最佳復配A1203再分別與AlN、BN和SiC三種高導熱填料制成復配填料填充PA6,研究高導熱填料的種類和添加量對復合材料性能的影響。最終得到力學性能和熱導率俱佳的導熱絕緣尼龍復合材料。
[Abstract]:The development of thermal insulating polymer composites is an important problem to solve the heat dissipation of electronic appliances and LED lamps. Based on the fact that the mechanical properties or thermal conductivity of thermal insulating composites reported in many literatures can not meet some high requirements, the thermal insulating composites were prepared by twin-screw extruder with PA6 as the matrix and Al _ 2O _ 3 as the thermal conductive filler. The effects of Al _ 2O _ 3 addition and particle size on the properties of composites were studied. The results show that the thermal conductivity of the composites increases with the increase of Al _ 2O _ 3 content, but the lower the mechanical properties are, the larger the particle size of Al _ 2O _ 3 is and the higher the thermal conductivity of PA6 / Al _ 2O _ 3 thermal insulation composites is, the worse the mechanical properties are. The thermal conductivity of PA6 composites filled with 40 渭 m Al _ 2O _ 3 is 1.213 W / (m K), 1.268 W / (m K) 1.289 W / (m K) and 1.455 W / (m K), respectively, while the tensile strength is 57.37 MPA, 53.77 nm, 52.12 MPA and 49.5 MPA, respectively, when the content of Al _ 2O _ 3 is 70 wt%, and 40 渭 m Al _ 2O _ 3-filled PA6 composites are 1.213 W / (m K), 1.268 W / (m K) and 1.455 W / (m K), respectively. In order to improve the mechanical properties of the composites, a sealed isocyanate silane was prepared from methyl ethyl ketone oxime and isocyanate, which was used as coupling agent for surface modification of Al _ 2O _ 3. The effect of the coupling agent on the properties of PA6 / Al _ 2O _ 3 composite was studied. SEM results showed that the sealing isocyanate silane could improve the dispersion of Al _ 2O _ 3 in the matrix and enhance the connectivity with the matrix. The results of equilibrium torque and mechanical properties show that the sealing isocyanate silane is unsealed during the melt processing of the composite, and then reacts in situ with the amino or carboxyl groups of the PA6 chain, which acts as a chain extender and improves the mechanical properties of the composite. The thermal conductivity of Al _ 2O _ 3 / PA _ 6 composite modified by blocked isocyanate silane was also improved. When the amount of Al _ 2O _ 3 was increased to 70 wt%, the tensile strength reached 85.16 MPA, which was higher than that of pure PA6, and the thermal conductivity reached 1.18 W / m K, 3.83 times of that of PA6. Considering the mechanical properties, thermal conductivity and processing properties of the composites, the filling amount of the thermal conductive fillers is determined to be 60 wts, but the thermal conductivity of the composites is relatively low. In order to improve the thermal conductivity, PA6 was filled with Al _ 2O _ 3 in different proportions. The results showed that the composite with 6 渭 m and 40 渭 m Al _ 2O _ 3 had the best properties when the mass ratio of 6 渭 m and 40 渭 m was 1:1. In order to further improve the thermal conductivity, the best composite A1203 was used to make PA6 filled with AlNNBNBN and sic respectively. The effects of the type and amount of high thermal conductivity fillers on the properties of composites were studied. Finally, thermal insulating nylon composites with good mechanical properties and thermal conductivity were obtained.
【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】：2015
【分類號】：TB332

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本文編號：2071331