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。     

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。     

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。     

导热PE-LD复合材料的制备与性能研究

采用低密度聚乙烯(PE-LD)为基体材料,石墨、Al N为导热填充材料,通过双辊混炼、模压制备了导热复合材料,并对该复合材料的导热性能、力学性能、热行为进行了分析。结果表明,随着石墨或Al N含量的增加,PE-LD/石墨复合材料和PE-LD/Al N复合材料的热导率逐渐增大;PE-LD/石墨复合材料的热导率高于PE-LD/Al N复合材料的热导率。当石墨与Al N的总质量分数为50%、石墨与Al N的质量比为4∶1时,PE-LD/石墨/Al N复合材料的拉伸强度、弯曲强度均达到最大值,分别为12.8,17.15 MPa;此时PE-LD/石墨/Al N复合材料的热导率达到最大值,为0.618 W/(m·K),略低于添加质量分数50%的石墨时的PE-LD/石墨复合材料的热导率[0.634 W/(m·K)];当石墨与Al N质量比为1∶4时,PE-LD/石墨/Al N复合材料的热导率为0.488 W/(m·K),高于只添加质量分数50%Al N的PE-LD/Al N复合材料的热导率[0.410 W/(m·K)]。当石墨和Al N总质量分数为50%时,随着Al N含量的增加,PE-LD的结晶度增大。     

高热导率聚丙烯/石墨复合材料的制备与性能

为了提高聚丙烯(PP)的导热性能,扩大其使用范围,采用价格低廉的商用石墨对PP进行改性,利用转矩流变仪制备了PP/石墨导热复合材料。研究了粒径为2μm和20μm的石墨及其复配对复合材料热导率及力学性能的影响。结果表明,复合材料的热导率随着石墨用量的增加而显著增大,20μm石墨填充的复合材料热导率高于2μm石墨填充的复合材料;由于石墨的各向异性,层内热导率远高于层间热导率;将两种粒径的石墨复配,固定石墨总质量分数为40%,当2μm石墨与20μm石墨质量比为1︰5时,复合材料层间和层内热导率达到最大,分别为1.125 W/(m·K)和2.897 W/(m·K),比相同用量下单一2μm石墨填充PP分别提高了121%和61%,比单一20μm石墨填充PP分别提高了3.6%和20%。随石墨用量增加,单一粒径石墨填充的复合材料拉伸强度和弯曲强度呈现先减小后增大的趋势,随复配填料中20μm石墨用量增加,复配填料填充复合材料的力学性能呈下降趋势,但弯曲强度变化不大,拉伸强度也在10 MPa以上。     

环氧树脂/镀银纳米石墨微片导热复合材料的制备与性能

以膨胀石墨为原料,采用超声分散法和化学镀法制得镀银纳米石墨微片,然后将其填充在环氧树脂基体中制备环氧树脂/镀银纳米石墨微片复合材料。结果表明,银粒子均匀镀覆在纳米石墨微片上,银层厚度为100 nm,有利于在环氧树脂基体中形成导热通路;与环氧树脂相比,环氧树脂/镀银纳米石墨微片复合材料的力学性能和热导率能都得到提高;当镀银纳米石墨微片含量为3 %时,复合材料的热导率为1.827 W/(m·K),比纯环氧树脂热导率提高了近5倍。     

线形低密度聚乙烯/碳纤维复合材料的热导率

用模压方式制备了线形低密度聚乙烯(PE-LLD)/CF(CF)复合材料,研究了CF表面偶联剂处理、分散方式及含量对复合材料热导率的影响。结果表明,用偶联剂处理过的CF填充PE-LLD复合材料热导率提高。用超声分散法制备的试样热导率优于球磨混合法和熔融混炼法制备的试样。随着CF含量的增加,PE-LLD/CF复合材料热导率提高,同时保持了良好的力学性能。当CF含量为10 %（质量分数,下同）时,用超声分散法制备的复合材料热导率达1.4 W/(m·K),是纯PE-LLD的6倍多。     

环氧树脂/聚多巴胺改性铝粉导热绝缘复合材料的制备与性能研究

采用化学包覆的方法在平均粒径分别为4.5 μm和20 μm的铝(Al)粉上包覆一层有机聚多巴胺(PDA),以环氧树脂(EP)为基体,包覆改性后的铝粉（PDA@Al）为导热填料,采用浇铸法制备了高导热绝缘环氧基复合材料(EP/PDA@Al)。结果表明,PDA@Al的加入有利于提高EP的热稳定性以及热导率,且当PDA@(20 μm)Al的含量为20 %(质量分数,下同)时,复合材料的热导率为0.521 W/（m·K）,相比纯EP的热导率提高了184 %;相对纯Al填充的EP复合材料,EP/PDA@Al复合材料的绝缘性能显著提高。     

聚偏氟乙烯/鳞片石墨/碳纤维高导热复合材料的制备

以聚偏氟乙烯（PVDF）树脂为基体,天然鳞片石墨（FG）、碳纤维（CF）为填料,采用熔融共混法制备了PVDF/FG/CF复合导热材料,并研究了FG、CF含量及其改性对复合材料导热性能和力学性能的影响。结果表明,复合材料的热导率随FG含量的增加而增大,力学性能随着FG含量的增加而降低;CF的加入提高了复合材料的力学性能,但热导率略有降低;对CF进行表面氧化处理将使得复合材料的热导率以及力学性能有所提高,当CF含量为5 %、FG含量为50 %时,复合材料的热导率为11.4 W/(m·K),拉伸强度为48 MPa,断裂伸长率为11 %。     

EVA/中空玻璃微珠隔热复合材料的制备与性能研究

采用乙烯-乙酸乙烯酯共聚物(EVA)为基质,以密度分别为0.18 g/cm3和0.29 g/cm3的中空玻璃微珠(GB) XS1和XS2为填料,通过挤出共混法制备EVA/GB隔热复合材料.探讨了不同中空玻璃微珠对复合材料热导率、热稳定性和拉伸强度的影响,并考察了复合材料与玻璃的黏合强度.结果表明,复合材料的热导率随GB用量的增加而不断下降;当GB用量为20份时,填充粒径均为40 μm的中李玻璃微珠XS1和XS2的复合材料的热导率分别为0.197 0 W/(m·K)和0.219 9 W/(m·K),与未填充EVA相比,分别下降了33.4%和22.5%;以中空玻璃微珠XS2为隔热填料时,所制备的EVA/GB复合材料的热导率随粒径的增大呈不断下降的趋势.填充粒径为40μm和90μm的中空玻璃微珠XS2的复合材料与玻璃的黏合强度在所考察的GB用量范围内均大于30 N/cm,并且随GB用量的增加缓慢下降.随GB用量的增加,填允高密度玻璃微珠XS2的EVA/GB复合材料的拉伸强度先增大,随后减小;当粒径为40μm的XS2用量为5份时,所制备的EVA/GB复合材料具有最大的拉伸强度32.26 MPa,比未填充EVA提高了16.5%.     

聚偏氟乙烯/类基体基团修饰石墨烯导热复合材料研究

采用含类基体基团的乙烯基三甲氧基硅烷修饰氧化石墨烯(GO),再用"一锅法"将其还原得到功能化石墨烯(F-GE),通过溶剂浇注法制备出界面性能优良的聚偏氟乙烯导热复合材料(PVDF/F-GE).利用红外光谱仪(FTIR)、扫描电子显微镜(SEM)、热导率测试仪、电子拉力试验机对复合材料的改性状态、微观形貌、导热性能和力学...     

PE-HD复合材料导热性能及力学性能的研究

通过双螺杆挤出机制备了高密度聚乙烯（PE-HD）/石墨/CaCO3增韧母料复合材料,并研究了石墨的表面处理、粒径、含量以及CaCO3增韧母料含量对复合材料导热性能及力学性能的影响。结果表明,偶联剂NDZ201对石墨表面具有较好的处理效果。石墨颗粒直径越小,复合材料的热导率及综合力学性能越高。CaCO3增韧母料能明显提高复合材料的热导率及缺口冲击强度。PE-HD/石墨/增韧母料250B的质量比为45/30/25时,复合材料的热导率可达1.72 W/(m·K),其缺口冲击强度与纯PE-HD相近,拉伸强度和弯曲强度分别比PE-HD提高了52 %和88 %。     

Characterisation of graphite nanoplatelets and the physical properties of graphite nanoplatelet/silicone composites for thermal interface applications

Thermally conducting and highly compliant composites were developed by dispersing graphite nanoplatelets (GNPs) into a silicone matrix by mechanical mixing. X-ray diffraction (XRD) indicates that the average thickness of the GNPs decreased from 60 to 35 nm during mechanical mixing. XRD-texture analysis demonstrated that GNP/silicone composites at 8 wt.% GNPs have a higher degree of basal plane alignment than at 20 wt.%. Differential scanning calorimetry showed that GNPs raised the curing temperature of silicone with no significant effect on the glass transition temperature. The thermal conductivity of the 20 wt.% composites reached 1.909 W/m.K, an 11-fold increase over silicone suggesting an improved dispersion compared to similar composites prepared by dual asymmetric centrifuge mixing. The percolation threshold for electrical conductivity of the composites was at ∼15 wt.%. The compressive modulus of the composite increased to twice that of silicone at 20 wt.%. The corresponding strength decreased by a factor of two compared to silicone and this can be attributed to the weak bonding at the GNP-silicone interface. Overall, these GNP/silicone composites, with a high thermal conductivity, low electrical conductivity and compliant nature are promising materials for use as thermal pads for thick gap filling thermal interface applications.     

Improving Properties of Poly(vinylidene fluoride) by Adding Expanded Graphite without Surface Modification via Water‐Assisted Mixing Extrusion

Expanded graphite (EG) is introduced into poly(vinylidene fluoride) (PVDF) by melt mixing extrusion with water injection. The results demonstrate that the unfunctionalized EG in composite prepared with water injection exbibits better dispersion than that in the one prepared without water injection due to the promoting role of water during extrusion. Thus, the PVDF/EG composite with loading of 4 wt% prepared by water‐assisted mixing extrusion (WAME) exhibits electrical conductivity of about three orders of magnitude higher than the neat PVDF and one order of magnitude higher than the one prepared without water injection. Comparing to the neat PVDF, the thermal conductivity of the composites prepared with and without water injection is increased by 101.5% and 75.0%, respectively. The introduced EG leads to increased Young’s modulus and tensile strength especially for the composite prepared by WAME. The present work indicates that WAME can promote the dispersion of EG in PVDF matrix without any extra functionalization.     

石墨和碳纤维改性聚酰亚胺复合材料的导热性能

以石墨、碳纤维(CF)、聚酰亚胺(PI)三元复合材料为研究对象,考察了CF体积含量对PI三元复合材料导热性能的影响,并采用了拟二元体系模型探讨了石墨和CF填充PI复合材料的协同效应。结果表明,CF的加入可以提高复合材料的力学性能：拉伸强度呈现先升高后降低的趋势,当CF含量为11.8 %（体积分数,下同）时,拉伸强度可达66.37 MPa;弯曲强度随着CF体积含量的增而增加,当CF含量为24.6 %时,弯曲强度可达103.3 MPa。复合材料热导率呈非线性增长,表明石墨和CF间存在协同效应;当CF含量为34.1 %时,环境扫描电子显微镜分析表明,CF与石墨能很好地搭接,增大了传热面积,复合材料热导率可达0.512 W/(m·K),约是其计算值的2倍。     

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％.     

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.     

Improved thermal conductivity of epoxy resins using silane coupling agent-modified expanded graphite

A silane coupling agent was used to modify the surface of expanded graphite (EG), which was subsequently used as a thermally conductive filler to fabricate diglycidylether of bisphenol-A (DGEBA)/EG composites with high thermal conductivity via hot blending and compression-curing processes. The surface characteristics of silane coupling agent-modified EG (Si@EG) were characterized by a variety of analytical techniques. The effects of the Si@EG content on the thermal conductivity, thermal stability, impact strength, and morphology of the DGEBA/Si@EG composites were investigated. The results revealed that the addition of 80 wt.% Si@EG increased the thermal conductivity of the composites from 0.17 to 10.56 W/m K, which was 61.1 times higher than that of pristine DGEBA. The initial decomposition temperature of the composite containing 80 wt.% Si@EG was 60.6°C higher than that of pristine DGEBA. The impact strength of the composites decreased from 2.0 to 0.87 kJ/m² when the Si@EG content increased from 0 to 80 wt.%. The scanning electron microscopy images of the fractured surfaces revealed that the EG sheets in the DGEBA matrix formed a continuous thermally conductive path at high Si@EG contents.