石墨烯纳米片/(酚酞聚芳醚酮-环氧树脂)双逾渗导热复合材料的制备和性能

为在较低的导热填料含量下提高环氧树脂(EP)的热导率,通过溶液法制备了石墨烯纳米片/(酚酞聚芳醚酮-EP) (GNP/(PEK-C-EP))复合材料。基于接触角测量计算并预测了GNP的选择性分布,并通过SEM和激光闪光法研究了GNP和PEK-C含量对GNP/(PEK-C-EP)复合材料的微观结构和热导率的影响。结果表明,当PEK-C的含量为20wt%时,GNP选择性分布在PEK-C中,形成了双逾渗结构的GNP/(PEK-C-EP)复合材料,从而构建了连续导热通道。当GNP含量为1wt%时,GNP/EP复合材料导热率最高达0.375 W(m·K)?1。当GNP含量为0.5wt%时,GNP/(PEK-C-EP)复合材料导热率最高达0.371 W(m·K)?1,较GNP含量为0.5wt%的GNP/EP复合材料热导率高48%,与GNP含量为1wt%的GNP/EP复合材料的热导率基本相同。表明GNP/(PEK-C-EP)复合材料的填料量减少了50%,利用双逾渗效应可以有效减少导热填料用量。此外,比较了纯EP和GNP/(PEK-C-EP)复合材料的玻璃化转变温度、热稳定性和热膨胀系数,结果表明,GNP/(PEK-C-EP)复合材料的热性能优于纯EP。      

石蜡/改性硅藻土复合相变储能材料的制备及性能研究

以石蜡为相变储能材料,改性硅藻土为载体,无水乙醇为溶剂采用溶液插层法制备了石蜡/改性硅藻土复合相变储能材料,利用综合热分析仪(TG-DSC)测定了复合材料的相变温度、相变潜热及复合材料的热稳定性,通过扫描电镜(SEM)、FT-IR分别对复合材料的微观结构及兼容性进行了表征,结果表明:复合相变储能材料中石蜡的适宜含量为65%,此时相变温度为53.7℃,相变潜热为147.93J/g,复合材料具有良好的热稳定性和兼容性。     

石蜡/SiO_2储能相变材料的制备与热性能研究

以工业石蜡为相变芯材,在硅烷偶联剂参与下,通过溶胶-凝胶法制备石蜡/SiO2储能相变材料。并利用透射电子显微镜,热重分析,傅里叶红外光谱仪和方差扫描量热法等测试技术对石蜡/SiO2储能相变材料的结构和性能进行了测试和分析,最后利用瞬态热线法对石蜡/SiO2储能相变材料的导热系数进行了测试。结果表明,石蜡/SiO2储能相变材料的相变芯材石蜡在吸热熔化后不会渗漏;石蜡/SiO2储能相变材料中石蜡的含量约为39%时,相变温度和相变潜热分别为39.15℃和59.33J/g;石蜡/SiO2储能相变材料的导热系数为0.0845 W/(m·K),可作为一种良好的保温隔热建筑材料。     

BN纤维对石墨烯微片/聚丙烯复合材料导热绝缘性能的影响

采用熔融共混法制备BN纤维-石墨烯微片/聚丙烯（BN纤维-GNP/PP）高导热绝缘复合材料,结合有限元模拟、SEM、XRD、导热导电测试结果,探究了BN纤维含量和长度对BN纤维-GNP/PP复合材料导热绝缘性能的影响。结果表明:BN纤维-GNP/PP复合材料中BN纤维含量和长度的增加可增大GNP分布范围,增大BN纤维与GNP的接触概率;在GNP含量为7wt%、100 μm BN纤维含量为20wt%时BN纤维-GNP/PP复合材料的热导率较PP提高了4.2倍,同时电绝缘性略有提高。模拟结果表明,高含量100 μm BN纤维的加入使BN纤维-GNP/PP复合材料导热网络的构建趋于完整,局部热通量较低的区域减少。片状GNP与纤维状BN二相填料的"协同效应",使GNP和BN纤维分别作为"岛"和"桥"形成了一种特殊的"双网络"结构,BN纤维作为高导热"桥"阻隔了相邻GNP间导电通路的形成,从而提高了BN纤维-GNP/PP复合材料的导热绝缘性能。      

石蜡相变储能模块的控温性能研究

目的 为了控制电子设备工作温度，研发一种相变储能模块，并研究其控温性能。方法 本文通过仿真对以32号石蜡、62号石蜡和质量分数为6%的膨胀石墨(EG)-62号石蜡为相变工质的储能模块进行研究，分析相变材料、翅片材料以及加热功率对相变储能模块控温性能的影响。结果 32号石蜡在900 s时接近完全融化，62号石蜡在2 000 s时才融化过半，膨胀石墨-石蜡复合材料在1 250 s就已经接近完全融化，填充62号石蜡的Al翅片模块的温升速率为0.035 ℃/s，Cu翅片模块的温升速率为0.03 ℃/s，相比未填充相变材料的模块温升速率分别降低了73.1%和70%。结论 具有不同物性参数的相变材料，在不同工况下其呈现的控温性能也各不相同，但是在较高功率工况下，熔点较低或导热系数较高的相变材料具有更好的控温性能。储能模块内部导热翅片对内部强化换热效果明显，翅片导热系数越高，越有利于模块的控温。     

纳米铜修饰多壁碳纳米管/石蜡相变驱动复合材料的制备及热性能

以油胺为分散稳定剂,在石蜡中热分解甲酸铜-碳纳米管复合物前驱体,单步制备了纳米铜修饰多壁碳纳米管(Cu-MWCNTs)/石蜡复合材料。通过XRD、TEM和DSC对Cu-MWCNTs/石蜡复合材料的物相、微观形貌及相变行为进行了表征和分析,并对其热敏性、热膨胀性和热稳定性及影响因素进行了分析研究。结果表明:纳米Cu原位沉积在MWCNTs外壁上,粒径为2~35nm。与纯石蜡相比,Cu-MWCNTs/石蜡复合材料的相变温度和相变潜热均明显降低。Cu-MWCNTs含量为0.2wt%的Cu-MWCNTs/石蜡复合材料具有较短的升温时间,体膨胀率降低较小,且多次加热后稳定性较好,可作为此类热敏微驱动器的理想材料。     

膨胀阻燃剂对石蜡/聚丙烯相变材料热降解及相变储能性能的影响

以聚磷酸铵(APP)、三嗪系成炭发泡剂(CFA)作为石蜡/聚丙烯定形相变材料(PCM)的膨胀阻燃剂。采用热重分析仪(TGA)分析阻燃石蜡/聚丙烯定形相变材料的热解特性,揭示了此体系的热稳定性,并以差示扫描量热仪(DSC)研究阻燃PCM的相变储能性能。结果表明:随着膨胀阻燃剂(CFA和APP)的添加,PCMs起始分解温度降低,残炭量由0.4%增加到17.1%,有效的提高了材料的阻燃性能和热稳定性。膨胀阻燃剂基本不影响相变材料的储能性能,但与聚丙烯(PP)的含量有关,PP含量越高,储能量越低,相变温度越滞后。     

新型复合相变储能材料Na/Paraffin的制备与性能分析

为提升广泛应用于相变储能领域的石蜡的导热系数,在手套箱内将导热系数高、熔点低、密度小的金属Na与石蜡复合为Na/paraffin新型相变储能材料,并对其导热系数、相变潜热及储/放热特性进行研究。结果表明:5%Na/95%paraffin复合相变储能材料导热系数较纯石蜡提高了17.6倍,储/放热速率均较纯石蜡提升了1倍;经过200次循环实验后,3%Na/97%paraffin复合相变储能材料相变温度由60.58℃下降到59.65℃,相变潜热由166.7520J·g~(-1)下降到160.5632J·g~(-1),热导率由2.33W·m~(-1)·K~(-1)减少到1.98W·m~(-1)·K~(-1)。     

膨胀石墨/石蜡相变复合材料有效导热系数的数值计算

通过膨胀石墨粉与石蜡混合制备相变复合材料可有效提高该储能材料的传热性能。为研究膨胀石墨/石蜡相变复合材料的导热机制,提出了膨胀石墨粉与石蜡混合后的3尺度层次固体有效导热系数计算方法。然后,通过数值模拟计算得到了具有不同体积分数和不同导热系数的膨胀石墨导热颗粒的膨胀石墨/石蜡相变复合材料的有效导热系数。结果表明:膨胀石墨能够有效地提高石蜡的导热性能,当膨胀石墨的体积分数为10%时,膨胀石墨/石蜡相变复合材料的有效导热系数是纯石蜡的9倍。此外,提高底层尺度的石墨片与石蜡的混合程度及降低底层尺度石墨的体积分数都能有效提高膨胀石墨/石蜡相变复合材料的有效导热系数。所得结论为探究膨胀石墨粉提高相变复合材料导热系数的机理奠定了基础。     

石蜡基碳纳米管复合相变材料热性能的研究

针对石蜡作为相变材料的改进研究,将多壁碳纳米管(CNTs)作为导热增强剂增加石蜡的导热系数。实验制备了CNTs用量为0.02%(wt,质量分数,下同)、0.05%和0.1%的石蜡/CNTs复合相变材料,通过差示扫描量热仪及导热系数仪分别对复合材料的相变特性和导热系数进行表征和测量。实验结果表明,复合材料导热系数随着CNTs用量的增加而提高,相变焓先增加后减小,CNTs用量为0.1%时,相变焓为152.8~157.9kJ/kg,较纯石蜡有所降低但变化不大,导热系数为0.487W/m·K(固态)和0.262W/m·K(液态),较纯石蜡分别提高21.14%和29.06%,稳定性较好,展现了良好的导热性能。     

Paraffin/carbon aerogel phase change materials with high enthalpy and thermal conductivity

Two kinds of carbon aerogels, graphene aerogels (GA) and carbon nanotubes-graphene aerogels (CGA), were prepared by modified hydrothermal method. The form-stable phase change materials (PCMs) were fabricated by adsorbing paraffin into carbon aerogels. Morphology, structure, form stability and thermal property were characterized by scanning electron microscope (SEM), in situ X-ray diffraction (in situ XRD) and differential scanning calorimeter (DSC). The results showed that GA presented wrinkled surface textures with curling edges, and carbon nanotubes (CNTs) were interspersed or attached to GA sheets. The phase transition temperature and the phase change enthalpy of the GA/paraffin PCM composite were 48.7 °C and 223.2 J/g, respectively. Thermal and mechanical properties of PCM composites achieved a qualitative leap with the adding of carbon aerogels. The PCM composites had a thermal conductivity of about 2.182 W/m K at the carbon aerogels loading fraction of 2 wt%. The form-stable PCM composites with high thermal conductivity and high enthalpy could be promising for thermal energy storage applications in construction field.     

聚吡咯/碳纤维纸电热复合材料的制备及性能

在碳纤维纸（CPP）上采用气相聚合法使吡咯单体发生聚合生成聚吡咯（PPY）,制备聚吡咯/碳纤维（PPY/CF）纸导电发热复合材料。通过FTIR、SEM、XRD对PPY/CF纸复合材料进行测试分析,并探究了CPP中CF的最佳质量分数及FeCl₃的最优溶度,研究了PPY/CF纸复合材料的力学性能和电热性能。结果表明,成功制备了PPY/CF纸复合材料,且PPY主要附着在芳纶浆粕上;采用CF质量分数为10 wt%的CPP且FeCl₃浓度为1.2 mol/L时,制备的PPY/CF纸复合材料具有最低的电阻率,为0.139 Ω·cm;PPY/CF纸复合材料与CPP相比不仅力学性能大幅提高,而且在低电压下,PPY/CF纸复合材料具有导电性能稳定、发热效果显著、热稳定性好等优点。      

纳米铜/石蜡相变驱动复合材料制备及热物理性能

采用高能球磨法制备了纳米铜/石蜡复合材料。通过TEM、 SEM、 XRD和DSC对复合材料的微观形貌、 物相及相变温度和潜热进行了表征和分析, 并研究了铜含量对复合材料的热敏性、 热膨胀性和热稳定性的影响。结果表明: 石蜡包覆在铜粒表面, 能显著提高其抗氧化性, 铜/石蜡复合颗粒近似球形, 粒径约为100 nm, 多个复合颗粒易团聚形成微米级颗粒; 铜含量对相变温度没有明显影响, 但相变潜热随铜含量的增加近似线性减少; 复合材料的热敏性随着铜含量的增加而提高, 但其热膨胀性则降低; 铜质量分数为60%的复合材料具有较短的升温时间, 体膨胀率降低较小, 且多次加热后稳定性较好, 可作为此类热敏微驱动器的理想材料。     

Preparation, characterisation and processing of carbon fibre/polyamide-12 composites for selective laser sintering

Aiming at developing carbon fibre/polyamide-12 (CF/PA) composite powders for manufacturing high-performance components by selective laser sintering (SLS), the preparation, characteristics and sintering process of the composite powders and mechanical properties of sintered components were studied. Surfaces of the carbon fibres were treated by the oxidation modification and coated with polyamide-12 through the dissolution-precipitation process to provide good interfacial adhesion and homogenous dispersion within the polyamide-12 matrix. The particle size and micro-morphology analyses show that the CF/PA composite powders with 30 wt%, 40 wt% and 50 wt% carbon fibres present the suitable powder sizes and format for SLS. The incorporation of carbon fibres into the polyamide-12 matrix decreases the initial melting temperature and consequently lowers the SLS part bed temperatures, implying lower energy requirement and less thermal degradation in the sintering process. The CF/PA composites also represent higher thermal stability than the pure polyamide-12. The CF/PA sintered components with 30 wt%, 40 wt% and 50 wt% carbon fibres exhibit the greatly enhanced flexural strengths by 44.5%, 83.3%, 114%, and the flexural modulus by 93.4%, 129.4%, 243.4%, respectively, as compared with the pure polyamide-12 sintered parts. Fractured surface analysis shows that the carbon fibres are encapsulated and bonded well with the polyamide matrix. The complex SLS parts with the thinnest wall of 0.6 mm, the density of 1.09 ± 0.02 g/cm³ and the relatively density of 94.13 ± 1.72% were manufactured using the CF/PA composite powder with 30 wt% carbon fibres. This study demonstrates that the CF/PA composite powders prepared by the surface treatment and dissolution-precipitation method represent suitable interfacial adhesion, filler dispersion, particle sizes and sintering behaviours for SLS and enable the manufacture of complex components with high performance.     

膨胀石墨-碳纤维/尼龙三元导热复合材料制备

以尼龙6（PA6）为基体,膨胀石墨（EG）和碳纤维（CF）作为导热填料,采用熔融共混法制备了EG/PA6、CF/PA6和CF-EG/PA6导热复合材料。重点研究当固定导热填料（CF和EG）填充量为40wt%时,CF与EG不同的填充比例对CF与EG的接触方式及CF-EG/PA6复合材料的导热性和力学性能的影响。结果表明,相比单一CF填充,EG的加入有利于CF-EG/PA6复合材料热导率的增加;CF:EG质量比是25:15时的EG-CF/PA6三元复合材料,热导率可以达到2.554 W/（m·K）,是PA6的8倍,拉伸强度提高了125.34%,弯曲强度提高了119.8%,同时具有优异的耐热性。SEM结果表明,纤维状CF与蠕虫状EG片层在适当的填充比例下可以形成"面接触"的三维网络结构,这种三维网络结构不仅显著增大EG-CF/PA6复合材料的热导率,而且明显提高了其力学性能和耐热性能。为研制填充型导热高分子材料提供了一条新思路。      

聚偏氟乙烯基复合材料的制备及介电性能

为有效改善聚合物基复合材料的介电性能,兼顾高介电常数和低填料量同时并存,采用以聚偏氟乙烯(PVDF)为基体树脂,钛酸钡(BT)和石墨烯(GNP)分别为介电填料和导电填料,在BT-GNP/PVDF复合体系内部构建微电容器结构.采用溶液法和热压法制备GNP/PVDF薄膜和BT-GNP/PVDF复合薄膜.结果表明,BT和GN...     

Evaluation of thermal,mechanical, and electrical properties of PVDF/GNP binary and PVDF/PMMA/GNP ternary nanocomposites

Graphene nanoplatelet (GNP) was incorporated into poly(vinylidene fluoride) (PVDF) and PVDF/poly(methyl methacrylate) (PMMA) blend to achieve binary and ternary nanocomposites. GNP was more randomly dispersed in binary composites compared with ternary composites. GNP exhibited higher nucleation efficiency for PVDF crystallization in ternary composites than in binary composites. GNP addition induced PVDF crystals with higher stability; however, PMMA imparted opposite effect. The binary composite exhibited lower thermal expansion value than PVDF; the value further declined (up to 28.5% drop) in the ternary composites. The storage modulus of binary and ternary composites increased to 23.1% and 53.9% (at 25 °C), respectively, compared with PVDF. Electrical percolation threshold between 1 phr and 2 phr GNP loading was identified for the two composite systems; the ternary composites exhibited lower electrical resistivity at identical GNP loadings. Rheological data confirmed that the formation of GNP (pseudo)network structure was assisted in the ternary system.     

Thermal and mechanical enhancements of polyetherimide/multi-walled carbon nanotube composite performance using "Solid Nano-Nectar" assisted melt dispersion

Manufacturing industrial-volume composites with well controlled uniform dispersion can be challenging, and is especially true for high performance polymers, such as polyetherimide (PEI). Toward that end, we report here a simple and versatile 2-Step processing approach which is based on formation of a high concentration of multi-walled carbon nanotube (MWCNT) filled PEI, which we call "Solid Nano-Nectar" (SNN). In this study we found surprisingly strong influences of the solvents that were used in the SNN preparation for dispersion of MWCNTs on the properties of the composites. The thermal conductivity of the SNN (made using DMF solvent) incorporated composites was about 72% higher than pure PEI, and 50% higher than that from 1-Step processing at same loading of 0.5 wt%. The thermal stability increased by 13 degrees C from this composite prepared by 1-Step processing, but a more noticeable change in thermal stability of 33 degrees C was observed at same loading using the 2-Step process. Such improvement was also observed in dynamic mechanical properties.