The dielectric properties of epoxy/AlN composites

In this paper, AlN ceramic powder is chosen to be mixed with epoxy to form epoxy/AlN composites, the effects of the content of AlN filler on the physical and dielectric properties of epoxy/AlN composites are developed. From the SEM observation, the particles of self-synthesized AlN powder, obtained by using combustion method, is less uniformity and the average particle size is about 3.12 μm. Only the AlN phase can be detected in the XRD patterns of the epoxy/AlN composites. The more AlN powder is mixed with epoxy, the higher crystal intensity of AlN phase will exist in the XRD patterns. As the content of AlN powder in the epoxy/AlN composites increases from 5 to 40 wt.%, the dielectric constant increases from 6.52 to 7.28 (measured at 1 MHz). The loss tangent of epoxy/AlN composites is slightly increased as the measured frequency increases. Moreover, the epoxy/AlN composites in this investigation show less pores as compared to other literatures. The results indicate that the fabrication process has an apparent effect on the decrease of porosities, and the composites with a low porosity will lead to a low loss tangent.     

Preparation and dielectric properties of bismuth-based dielectric/PTFE microwave composites

PTFE-based microwave composites filled with bismuth-based pyrochlore dielectric ceramics were prepared by using the powder processing technology. The effect of ceramic powder content on dielectric properties was studied. The relative permittivity was also predicted using percolation theory. The results indicated that as the content of ceramic powder increased, both the relative permittivity and dielectric loss of composites increased, showing excellent frequency in a wide spectral range. The theoretical result predicted by percolation theory is in good agreement with the experimental data.     

纳米石墨片/环氧树脂复合材料的制备及性能

分别采用低温固化剂和高温固化剂制备了纳米石墨片/环氧树脂复合材料。通过电阻测试仪和材料试验机研究了纳米石墨片的含量对复合材料导电性能和力学性能的影响规律,并将溶液混合法与直接混合法制备的复合材料的性能进行对比,同时比较了纳米复合材料的性能与微粉石墨/环氧树脂复合材料的性能。结果表明,溶液混合法制备的复合材料逾渗阈值更低,可得到填料质量分数达60%、体积电阻率为0.0085 Ω·cm的纳米复合材料。当填料质量分数高于4%时,纳米复合材料的力学性能低于微粉复合材料。     

Simultaneously improved toughness and dielectric properties of epoxy/graphite nanosheet composites

Very thin graphite nanosheets are obtained using an ultrasonic irradiation method, and epoxy/graphite nanosheet composites with different filler content are fabricated using the diglycidylether of bisphenol A epoxy matrix. An investigation of structural characteristics and mechanical and dielectric properties of the nanocomposites is carried out. SEM micrographs shows that the thickness of a single layer graphite nanosheet is about 20 nm whereas FTIR studies indicates that the surfaces of the graphite nanosheets are enriched with hydroxyl and carbonyl groups. The dielectric constants of the composites are increased with increases in graphite nanosheet content lower than 3.5 wt%, and are still higher than 100 in the high frequency range with 3.5 wt% graphite filler content. The tensile strength and storage modulus of the composites increase with increasing nanosheet concentration. These epoxy/graphite nanosheet composites, which show both high dielectric constant and toughness, could have potential application in embedded capacitor technology. POLYM. ENG. SCI., 50:1734–1742, 2010. © 2010 Society of Plastics Engineers     

Thermal and dielectric properties of the aluminum particle/epoxy resin composites

Microsized aluminum/epoxy resin composites were prepared, and the thermal and dielectric properties of the composites were investigated in terms of composition, aluminum particle sizes, frequency, and temperature. The results showed that the introduction of aluminum particles to the composites hardly influenced the thermal stability behavior, and decreased T_g of the epoxy resin; moreover, the size, concentration, and surface modification of aluminum particles had an effect on their thermal conductivity and dielectric properties. The dielectric permittivity increased smoothly with a rise of aluminum particle content, as well as with a decrease in frequency at high loading with aluminum particles. While the dissipation factor value increased slightly with an increase in frequency, it still remained at a low level. The dielectric permittivity and loss increased with temperature, owing to the segmental mobility of the polymer molecules. We found that the aluminum/epoxy composite containing 48 vol % aluminum‐particle content possessed a high thermal conductivity and a high dielectric permittivity, but a low loss factor, a low electric conductivity, and a higher breakdown voltage. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

丁苯橡胶/环氧树脂复合材料的制备及性能

采用机械共混法制得丁苯橡胶(SBR)/双酚A缩水甘油醚型环氧树脂(EP)复合材料,考察了橡胶硫化体系与EP固化体系的相互影响以及SBR/EP(质量比,下同)对复合材料结构和力学性能的影响。结果表明,SBR/EP复合材料中交联的形成分为橡胶交联和树脂交联网络2个阶段;橡胶硫黄硫化体系加速了EP的固化。复合材料中SBR与EP出现了相分离现象;当SBR/EP达到70/30时,EP形成连续相,复合材料成为具有双网络结构的橡塑复合材料;随着EP用量的增大,复合材料的拉伸强度、撕裂强度、100%定伸应力、硬度逐渐增大,扯断伸长率逐渐下降。     

碳纳米管增强环氧／石墨复合材料的制备与性能研究

采用粉末冶金法制备了碳纳米管增强环氧／石墨复合材料,并研究了酸洗处理对复合材料弯曲强度、硬度和导电性能的影响。结果表明：与未处理碳纳米管相比,酸处理的碳纳米管增加了环氧／石墨复合材料的弯曲强度和硬度,降低了电阻率。酸处理的碳纳米管增强环氧／石墨复合材料的弯曲强度达到21．9MPa,比未添加碳纳米管时提高了近22％;同时复合材料的硬度达到最大值21．7HS,比未添加碳纳米管时提高了近10％;复合材料的电阻率达到了最小值45036μΩ·cm,比未添加碳纳米管时复合材料的电阻率降低了近17％。     

炭黑/环氧树脂复合材料的制备及电性能研究

介绍了以二氧化硅为分散剂的炭黑/二氧化硅/环氧树脂基复合材料的组成、制备、导电机理,渗流阈值及PTC效应。分析了影响其PTC效应的因素,包括炭黑粒子、聚合物基体以及材料的加工工艺等。     

环氧树脂/纳米纤维素复合材料的制备与性能研究

以木粉为原料制备纳米纤维素（CNF）,经甲基丙烯酸缩水甘油酯（GMA）改性后采用溶液共混法与环氧树脂（EP）复合,制得EP/CNF⁃GMA复合材料;通过对EP/CNF、EP/CNF⁃GMA复合材料力学性能、透光性能、亲水性、热稳定性和微观结构的表征,研究了CNF和GMA含量对复合材料性能的影响及其机理。结果表明,EP/CNF复合材料的拉伸强度、断裂伸长率、透光率随CNF含量的增大呈先增后减的变化趋势,亲水性随CNF含量的增大而增大;CNF含量为0.6 %（质量分数,下同）时,EP/CNF复合材料性能最优,拉伸强度为32.166 MPa,断裂伸长率为20.995 %,600 nm处透光率为79.8 %,接触角为77.34°。经GMA改性后,CNF与EP的相容性得到了改善,提升了EP/CNF复合材料的力学性能和热稳定性;随GMA含量的增加,EP/CNF⁃GMA复合材料的拉伸强度、断裂伸长率、透光率和亲水性均发生变化;GMA含量为4.8 %时EP/CNF⁃GMA复合材料性能最佳,拉伸强度为57.933 MPa,断裂伸长率为18.762 %,600 nm处透光率为86.3 %,接触角为81.42 °。     

Preparation and properties of silicon nitride/glass fiber/epoxy composites

Silicon nitride/glass fiber (Si₃N₄/GF) hybrid fillers are performed to prepare the Si₃N₄/GF/epoxy composites. Results showed the thermal conductivities of the Si₃N₄/GF/epoxy composites that are improved with the addition of Si₃N₄, and the thermal conductive coefficient λ is 1.412 W/mK with 38 vol% modified Si₃N₄/GF hybrid fillers (30 vol% Si₃N₄ + 8 vol% GF), seven times higher than that of pure epoxy resin. The flexural strength and impact strength of the composites are optimal with 13 vol% modified Si₃N₄/GF hybrid fillers (5 vol% Si₃N₄ + 8 vol% GF). The dielectric constant and dielectric loss of the composites are increased with the increasing addition of Si₃N₄. For a given Si₃N₄/GF hybrid fillers loading, the surface modification can further improve the thermal conductivities of the Si₃N₄/GF/epoxy composites. POLYM. COMPOS., 35:1338–1342, 2014. © 2013 Society of Plastics Engineers     

新型液晶聚氨酯/环氧树脂复合材料的制备及性能

以联苯二酚,2,4-甲苯二异氰酸酯(2,4-TDI),乙二醇,N,N'-二(ω-羟乙基)均苯四甲酰二亚胺(BHDI)为单体,加成反应合成了1种同时含有联苯基和亚胺基的新型液晶聚氨酯(LCPBI),通过IR,DSC、偏光显微镜及X射线衍射仪对其结构和性能进行表征和分析。将该液晶聚氨酯与环氧树脂(E-51)共混制备了液晶聚氨酯/环氧树脂复合材料,通过力学性能测试,热重分析和电镜分析对其性能进行了研究并探讨了其增韧机理。结果表明,加入质量分数为3%的LCPBI,可使复合材料的冲击强度提高2.5倍,拉伸强度和弯曲强度也有不同程度的提高,热分解温度提高15～20℃。     

马来酸酐三元共聚物的制备及其复合材料的介电性能研究

以马来酸酐、乙酸乙烯酯和丙烯酸为单体,采用沉淀聚合法合成马来酸酐-乙酸乙烯酯-丙烯酸三元共聚物。将共聚物与锆钛酸铅(PZT)粉末热压共混,制备出系列高介电性的陶瓷/聚合物复合材料。通过对PZT/聚合物复合材料进行介电性能分析,结果表明复合材料的介电常数随PZT含量的增加而增加,介电损耗随PZT含量增加而减少。与不含丙烯酸的马来酸酐-乙酸乙烯酯二元共聚物/PZT复合材料相比,介电常数提高1倍左右,表现出超高的介电性能。高含量马来酸酐三元共聚物的采用有利于提高复合材料的介电性能。     

PANI-PMN/环氧树脂复合材料的制备

用自制的聚苯胺（PANI）包覆铌镁锫钛酸铅（PMN）粉末为功能相，以环氧树脂为基体，制备了PANI—PMN／环氧树脂复合材料。当w（PANI—PMN）小于60％时，随w（PANI～PMN）的增大复合材料的压缩强度有所提高。当w（PANI-PMN）大于60％时，压缩强度降低。随着w（PANI—PMN）的提高，试样的电导率增大。PANI包覆PMN制备的复合材料的阻尼损耗因子提高。在PANI—PMN／环氧树脂复合材料中，除环氧树脂的黏弹性阻尼、填料与基体的相互作用耗能外，还存在压电阻尼作用，并且具有一定电导率的体系有利于压电阻尼发挥作用。     

Mechanical,thermal, and dielectric properties of aluminum nitride/glass fiber/epoxy resin composites

The treated hybrid fillers of aluminum nitride/glass fibers (AlN/GF) were performed to prepare the AlN/GF/epoxy composites by casting method. Results showed that the flexural and impact strength of the composites were increased firstly, but decreased with the excessive addition of AlN. The mechanical properties were optimal with 5 wt% treated AlN. The thermal conductivities of the composites were improved with the increasing content of AlN, and the thermal conductive coefficient λ was 1.412 W/mK with 70 wt% treated AlN, about seven times higher than that of pure epoxy resin. The dielectric constant and dielectric loss of the composites were increased with the increasing content of AlN. For a given AlN/GF hybrid fillers loading, the surface treatment of AlN/GF hybrid fillers exhibited a positive effect on the mechanical properties and thermal conductivities of the composites. POLYM. COMPOS., 35:381–385, 2014. © 2013 Society of Plastics Engineers     

环氧树脂基介电复合材料的制备和性能研究

以环氧树脂(EP)为基体树脂、经硅烷偶联剂改性后的压电陶瓷钛酸钡(BaTiO3)为增强填料,采用浇铸法制备了有机/无机介电复合材料。研究了填料用量对复合材料介电性能、力学性能和热性能的影响。实验结果表明,BaTiO3能显著提高材料的介电常数,当w(BaTiO3)=60%时,复合材料的介电常数为23.6,比纯EP的介电常数(4.0)提高了近6倍,而且复合材料的介电常数受频率影响较小,具有较好的频率稳定性;随着BaTiO3含量的增加,材料的弯曲强度和冲击强度都呈先增后减的趋势,最大弯曲强度和冲击强度分别为123.8 MPa和26.3 kJ/m2;材料的热稳定性研究表明,材料的起始热分解温度随着BaTiO3含量的增加而提高,材料的耐热性能得到改善。     

Coir pith/nylon/epoxy hybrid composites: Dynamic mechanical,ageing, and dielectric properties

Coir pith/epoxy, nylon/epoxy, and coir pith/nylon/epoxy composites were prepared keeping the coir pith content at 65%. Two series of the above composites, one with chemically treated coir pith and another without chemically treated coir pith were fabricated. The Dynamic mechanical properties of composites were evaluated with respect to type of composites and treatment. Storage modulus was found to improve with hybridization and chemical treatment. Meanwhile Tan δ of composites were found to be decreased with hybridization and chemical treatment. Compressive strength of composites with chemically treated coir pith was found to be higher than other composite samples and this has been justified in terms of increased crystallinity of coir pith on treatment. The studies on sea water ageing of composites also indicated improved stability of composites with hybridization and chemical treatment. The dielectric properties of the boards were also evaluated in this investigation and the boards were found to show lower dielectric constant with chemical treatment of coir pith. POLYM. COMPOS., 38:1671–1679, 2017. © 2015 Society of Plastics Engineers     

耐高温高导热环氧树脂／玻纤／BN复合材料的制备

以4,4-二氨基二苯砜（DDS）和内亚甲基四氢邻苯二甲酸酐（NA）为复配固化剂,采用高温模压成型法制备耐高温高导热环氧树脂／玻纤／氮化硼（BN）复合材料。探讨了BN用量和偶联剂处理对复合材料冲击强度、导热性能和电阻率的影响。结果表明：当nDDS：nNA=3：1时,复合材料的耐热性能最佳。当BN质量分数为8％时,复合材料的冲击强度最高;导热性能随BN用量的增加而增加,当BN用量为15％时,热导率为0．7560W／（mk）,此时复合材料仍保持较高的体积、表面电阻率;当BN填充量为一定值时,偶联剂处理使冲击强度和导热性能得到进一步提高。     

石墨烯的制备及石墨烯/PVDF合材料介电性能的研究

通过Staudenmaier法制备了完全氧化的氧化石墨(GO),并通过高温热膨胀制备了单层石墨烯(graphene).用FT-IR、TG和XRD对GO的氧化程度、含氧官能团进行了表征;Graphene的XRD测试结果证明了单层石墨的存在.利用超声共混法制备了graphene/PV DF介电纳米复合材料.介电性能的测试表...     

环氧树脂/ABS复合材料的制备及性能表征

以环氧树脂为基体,苯乙烯-丙烯腈-丁二烯（ABS）树脂为增韧剂,制备了环氧树脂/ABS复合材料,讨论了增韧剂对复合材料的热性能和机械性能的影响。结果表明,ABS的添加可提高复合材料的断裂韧性。扫描电镜结果显示,基体的剪切屈服和橡胶颗粒的微孔洞是ABS增韧环氧树脂的主要增韧机理。