BN填充PA6基导热绝缘复合材料导热性能研究

以聚酰胺6（PA6）为基体, 氮化硼（BN）作为导热填料,经双螺杆挤出机熔融共混,模压成型制得导热绝缘复合材料。研究了BN含量、粒径、形状和不同BN粒径复配对复合材料导热性能的影响,并研究了BN含量和粒径对复合材料绝缘性能的影响。结果表明,在各种粒径下,复合材料热导率均随BN填充量的增加而增大;在BN粒径为5 μm、填充量为25 %（体积分数,下同）时,复合材料热导率达到1.2187 W/(m·K);在BN填充量相同时,填料粒径对复合材料热导率的影响不是简单的单调规律,呈现50、100 μm时较小,1、5、15 μm时较大,150 μm时最大的规律;片状BN填料比球状BN填料更有利于提高复合材料的热导率;2种不同粒径填料复配所填充的复合材料的热导率大于单一粒径填充的复合材料;5 μm与150 μm粒径BN复配,在填充量为20 %,配比为1:3时,复合材料的热导率最大,达到1.3753 W/(m·K),为纯PA6的4.9倍;在不同BN含量和粒径下,复合材料体积电阻率均能达到10000000000000 Ω·cm以上,满足绝缘性能。     

膨胀石墨混杂填充聚丙烯复合材料导热性能研究

以不同粒径的膨胀石墨(EG)为填料,通过双辊混炼热压成型制备聚丙烯(PP)/EG导热复合材料,研究了EG填充量、粒径和不同粒径混杂填充对复合材料导热性能的影响。结果表明:随着EG填充量的增加,复合材料的热导率提高。当填充量超过30%时,热导率提升幅度增大,达到渗流阈值;当EG填充量为50%时,复合材料的热导率达到1.791W/(m.K);大粒径填料粒子提高复合材料热导率的能力优于小粒径粒子;大小粒径按合适比例混杂填充得到的复合材料热导率最高。     

鳞片石墨填充PA66导热复合材料的性能

利用鳞片石墨(FG)的高导热性能,采用熔融共混法将鳞片石墨填充于聚酰胺66(PA66)中,制备出FG/PA66导热复合材料,研究了石墨填充量以及粒径对复合材料导热性能和力学性能的影响。研究表明:随着FG填充量的增加,复合材料的导热率显著增加,而力学性能逐渐降低。当填充量为50%时,导热率达到了3.07 W/(m·K),是纯PA66的12.3倍。力学性能在50%填充量时为最小值,拉伸强度和冲击强度分别为59.3 MPa和3.03 kJ/m~2。在相同填充量下,复合材料的导热率随着粒径增大而增大,当鳞片石墨的填充量为40%,填料粒径为150μm时,导热率达到最大值,为2.38 W/(m·K)。力学性能随粒径变化呈现先增大后减小的趋势,当粒径为100μm时,复合材料的力学性能最佳。     

氮化铝/尼龙6复合材料导热性能的研究

采用熔融共混法制备了Al N/PA6导热复合材料,并深入研究了硅烷偶联剂KH-550含量、导热填料Al N粒径和含量对复合材料导热性能的影响。结果表明,偶联剂对Al N/PA6界面的键合作用以及在Al N表面形成的包覆结构导致了复合材料的热导率随偶联剂含量的增多而先增大后减小。当偶联剂的加入量为1.0wt%时,复合材料的热导率最好,达到0.451 W/(m·K)。Al N粒径大小会影响复合材料的Al N/PA6界面多少和Al N在基体中的分散均匀性,从而影响其导热性能。当Al N粒径为3μm时,热导率最高。随着Al N含量的增多,导热链会逐渐形成,从而使得复合材料的热导率逐渐增大,且增长幅度呈先缓后急的趋势。     

偶联剂对 PA6/h-BN 复合材料导热性能的影响及复合材料制备工艺优化

以硅烷偶联剂(KH550)与钛酸酯偶联剂(TM-P)改性氮化硼(h-BN)为导热填料,聚酰胺6(PA6)为基体,通过熔融共混法制备了导热绝缘复合材料。并通过正交实验研究了h-BN粒径、偶联剂用量和h-BN填充量对复合材料导热性能的综合影响。结果表明,在h-BN体积分数为20%,KH550、TM-P最佳用量分别为2.5%、1%(偶联剂与h-BN质量比)时,TM-P对复合材料热导率的提升效果优于KH550;复合材料的热导率提升率随h-BN添加量的增加呈先增加,然后不变,再减小的趋势;复合材料的屈服强度随h-BN填充量的增加而减小,KH550对复合材料力学性能的改善优于TM-P;TM-P用量为1%,h-BN体积分数为25%,h-BN粒径为10~15μm时复合材料的热导率为2.446 W/(m·K)。     

PA66导热绝缘塑料的制备与性能

通过尼龙66(PA66)与大粒径MgO共混经双螺杆挤出机挤出制备了导热绝缘塑料。研究了热导率与MgO填充量的关系。该导热绝缘塑料的热扩散系数和热导率随MgO填充量的增加而增大。在MgO填充量达到70%时,热导率达到1.9 W/(m.K),同时仍保持较好的力学性能和一定的电绝缘性能。热失重分析表明,该导热绝缘塑料的热分解温度受MgO填充量的影响,有约10℃的变化,低填充量(40%和50%)时,因MgO具有良好的导热性能,试样中的PA66几乎完全被分解汽化。     

高导热高介电BT/SiC/PA6复合材料的制备及性能研究

以聚酰胺(PA6)为基体,氮化硅(SiC)为导热填料,钛酸钡(BT)为介电填料,通过热压法制备出系列复合材料;研究了不同粒径填料的搭配对材料导热与介电性能的影响。结果表明:在填充量较低时,使用混合粒径导热填料能产生一定的级配效应,从而提高复合材料的导热性能。总填充量为26%时,以4∶1的比例,用粒径为0.5~0.7μm和3μm的SiC共同填充PA6,制备获得了最高导热系数为0.9198W/(m·K)的复合材料,而不同粒径、不同功能的混合功能填料还能产生协同效应,进一步提升材料的导热性能并使材料同时获得较好的介电性能,当SiC填充量为20%,BT填充量为20%时,复合材料的导热系数达到1.1110W/(m·K),介电常数到达16(100Hz),损耗保持在0.075(100Hz)左右。     

PE/多层石墨导热复合材料的制备与性能

PE、GPE为基材,多层石墨、石墨为填料,采用机械混炼法制备高导热塑料复合材料。SEM分析表明PE/多层石墨比GPE/多层石墨复合材料的插层效果更好。研究填料对复合材料的热导率和热稳定性的影响。结果表明:导热复合材料的热导率随填料填充量的增大而增大,多层石墨的填充量达到100%时,热导率为4.15 W.m-1.k-1。并且在相同填充量下PE/多层石墨较之GPE/多层石墨、PE/石墨、GPE/石墨的导热率更高。TGA分析表明:填充多层石墨、石墨的导热塑料复合材料热稳定性高于未填充的PE。经研究提出,形状比(径厚比)大和导热率高的导热填料更易形成导热网链;为了不影响导热填料的分散性,可先使基体材料与填料先混合均匀再增加其韧性、黏度等。     

氮化铝填充导热复合材料导热性能的有限元分析

采用有限元方法分析了氮化铝(Al N)填料粒径、含量以及树脂种类等因素对复合材料导热性能的影响。模拟结果显示:填料体积分数小于20%时,导热系数的模拟结果和试验结果接近,在高填充时,导热系数模拟结果低于试验结果,但是变化趋势和试验结果一致;低填充量时填料粒径对导热系数影响不大,高填充时,大粒径填料可以增强复合材料导热系数;树脂本身的导热性能越高,复合材料的导热性能越好。     

BN填充PA6高导热复合材料的性能研究

采用氮化硼(BN)作为导热填料,通过熔融共混法制备聚酰胺6/氮化硼(PA6/BN)导热复合材料,通过扫描电子显微镜(SEM),万能试验机等方法研究了经过硅烷偶联剂(KH550)处理的BN对PA6/BN复合材料的导热性和力学性能的影响。实验结果表明:在填充相同含量(10%)的BN情况下,随着硅烷偶联剂添加量的增加,断面越来越粗糙,BN表面被树脂包裹,形成导热通路,且导热系数不断提高形成更长的导热通路,减少热阻,从而提高热导率;当偶联剂含量超过3%时,复合材料的导热系数基本稳定不再增加,导热系数趋于稳定。进一步研究BN的添加量对PA6/BN导热复合材料的力学性能和导热系数的影响,随着BN含量的增加,复合材料的缺口冲击强度逐渐下降;随着BN含量的增加,PA6/BN复合材料的弯曲强度先增加后降低,而弯曲模量不断增加,随着BN添加量达到30%时,导热系数达到0.628 7 W/(m·K),是未添加BN的2.67倍。     

Effects of flake graphite on property optimisation in thermal conductive composites based on polyamide 66

In this study, in order to improve the thermal conductivity of polyamide 66(PA66), PA66 composites filled with flake graphite (FG) were prepared by twin-screw extruder. Effects of filler content, particle size and particle size mixing on thermal conductivity, mechanical and rheological properties of the composites were investigated. The results showed that as FG content increased from 0 to 50 wt-%, thermal conductivity of the composites filled with 100 μm FG gradually increased, whereas mechanical properties and rheological properties decreased. At 50 wt-% loading, thermal conductivity reached 3.07 W/(m K). With the increase of particle size, thermal conductivity and rheological properties of the composites improved, but mechanical properties increased first and then decreased. The composite filled with 100 μm FG had relatively optimal mechanical properties. Particle size mixing can improve thermal conductivity and the maximum value was achieved in the 1:2 mass ratio of 20 and 100 μm particles.     

Effect of the particle size of Al2O3 on the properties of filled heat‐conductive silicone rubber

An elastomeric thermal pad with a thermal conductivity of 1.45 W/m K, needed for the heat dissipation of microelectronics, was obtained with hybrid alumina of different particle sizes as a filler and silicone rubber (vinyl‐end‐blocked polymethylsiloxane) as the matrix. The effects of the amount, particle size, and mixing mass ratio of the filler particles on the thermal conductivity and mechanical properties of silicone rubber were investigated. The results indicated that the thermal conductivity of the rubber filled with larger particles was superior to that of the rubber filled with the smaller grain size, and the rubber incorporated with a mixture of hybrid particles at a preferable mass ratio exhibited higher thermal conductivity than the rubber for which a filler with only a single particle size was used. In addition, the surface treatment of the hybrid filler with 3‐methacryloyloxypropyltrimethoxysilane could increase the thermal conductivity of the composite rubber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1312–1318, 2007     

LDPE/PEG插层剥离改性氮化硼导热复合材料的制备及其性能

以聚乙二醇(PEG)为插层剂,通过机械球磨法制备了PEG插层剥离改性氮化硼。以低密度聚乙烯(LDPE)为基体,PEG插层剥离改性氮化硼为导热填料,采用双辊开炼、压片成型制备LDPE/PEG插层剥离改性氮化硼导热复合材料,研究了改性氮化硼用量及粒径对复合材料导热性能、力学性能和电绝缘性能的影响。结果表明:随着PEG插层剥离改性氮化硼用量的增加,复合材料的导热性能提高,拉伸强度和弯曲强度提高,悬臂梁缺口冲击强度下降;粒径较大的PEG插层剥离改性氮化硼对复合材料导热性能的提高更显著;复合材料的表面电阻下降,但仍保持在1010数量级,具有优异的电绝缘性能。     

天然鳞片石墨/环氧树脂复合材料的制备及导热性能研究

以天然鳞片石墨为导热填料,E44型环氧树脂为基体,采用超声分散法制备天然鳞片石墨/环氧树脂复合导热材料.系统考察了天然鳞片石墨用量、石墨粒度和炭黑添加量等因素对复合材料导热性能的影响.结果表明:随着天然鳞片石墨用量增加,复合材料的导热系数增大,抗压强度先增加后减小;复合材料的导热系数随天然石墨粒径的增大而增大,抗压强度先减小后增加;在石墨/环氧树脂复合导热材料中添加不同用量的炭黑时,随着炭黑添加量的增加,复合材料的抗压强度增大,导热系数先增大后减小.制备天然鳞片石墨/环氧树脂复合导热材料的最佳配方为天然鳞片石墨用量45％,粒径≤270 μm,炭黑用量2％.     

导热PA6复合材料导热性能的研究

将氮化硼和氧化铝等助剂混合后,经过平行双螺杆挤出机制备了导热PA6复合材料,研究了将不同粒径的氮化硼和氧化铝复配对尼龙6复合材料导热系数的影响。结果表明:采用不同粒径的氮化硼和氧化铝复配,添加60%的含量可得到导热系数为1.869的导热PA6复合材料。     

Effects of chicken eggshell filler size on the processing,mechanical and thermal properties of PVC matrix composite

The effects of filler particle size of poly(vinyl chloride)/chicken eggshell powder (PVC/ESP) composites on the processing, tensile properties, morphology and thermal degradation were investigated. The mixing of composites was done using Rheomix internal mixer. The processing torque of PVC/ESP composite at a particle of 0.2 μm exhibits lower processing torque compared to that at a particle size of 7 μm due to the dispersive resistance from larger ESP filler particles. Good interfacial adhesion exists between the filler and matrix in composites prepared via a filler particle size of 0.2 μm, which has improved the tensile strength and modulus of PVC/ESP composite compared to a filler particle size of 7 μm as justified from FESEM images on the tensile fracture surface of the composites. Thermogravimetric analysis results show that the filler particle size of 0.2 μm composite exhibits higher thermal stability compared to the filler particle size of 7 μm composite.     

Influence of filler type and content on thermal conductivity and mechanical properties of thermoplastic compounds

Combining thermal conductivity with electrical isolation is a very interesting topic for electronic applications in order to transfer the generated heat. Typical approaches combine thermally conductive fillers with a thermoplastic matrix. The aim of this work was to investigate the influence of different fillers and matrices on the thermal conductivity of the polymer matrix composites. In this study, various inorganic fillers, including aluminum oxide (Al₂O₃), zinc oxide (ZnO), and boron nitride (BN) with different shapes and sizes, were used in matrix polymers, such as polyamide 6 (PA6), polypropylene (PP), polycarbonate (PC), thermoplastic polyurethane (TPU), and polysulfone (PSU), to produce thermally conductive polymer matrix composites by compounding and injection molding. Using simple mathematical models (e.g., Agari model, Lewis–Nielson model), a first attempt was made to predict thermal conductivity from constituent properties. The materials were characterized by tensile testing, density measurement, and thermal conductivity measurement. Contact angle measurements and the calculated surface energy can be used to evaluate the wetting behavior, which correlates directly with the elastic modulus. Based on the aforementioned evaluations, we found that besides the volume fraction, the particle shape in combination with the intrinsic thermal conductivity of the filler has the greatest influence on the thermal conductivity of the composite.     

Thermal conductivity of several geopolymer composites and discussion of their formulation

We fabricated 50.8-mm cube-shaped samples of metakaolin geopolymer (GP) composites with various additives chosen to increase or decrease the thermal conductivity of the composite. Sodium-based GP (NaGP) and GP composites were more conductive than potassium-based GP (KGP) composites for a given phase fraction of filler, but the maximum amount of filler phase was higher with KGP due to the lower viscosity of the KGP mixture. The highest thermal conductivity achieved was about 8 W/m K by KGP + 44-vol% graphite flakes, whereas NaGP + 27 vol% graphite flakes reached 4.7 W/m K. The thermal conductivity was strongly affected by the moisture remaining in the composite, which appeared to have a greater effect at higher filler content. On the other hand, the size of alumina particles (6, 40, or 120 μm) did not have any apparent effect on thermal conductivity for the same filler content. Larger particles caused less change in mixture viscosity, though, thus permitting incorporation of higher filler phase fractions and therefore higher thermal conductivity.