高密度聚乙烯/铅硼复合材料屏蔽性能和力学性能研究

研究了高密度聚乙烯/铅硼复合材料的屏蔽性能和力学性能,通过屏蔽仿真比较了密度及碳化硼（B4C）含量对屏蔽性能的影响,通过试验比较了B4C含量对屏蔽性能、弯曲强度及冲击强度的影响。仿真结果表明,随聚乙烯/铅硼复合材料密度升高,快中子屏蔽性能下降,热中子屏蔽性能和γ屏蔽性能提高;保持聚乙烯/铅硼复合材料密度不变,随B4C含量的提高,中子屏蔽性能提高而γ屏蔽性能下降;实验数据表明,随B4C含量的升高,高密度聚乙烯/铅硼材料的快中子屏蔽性能、热中子屏蔽性能升高,γ屏蔽系数下降,冲击强度和弯曲强度下降明显,屏蔽性能测试结果和仿真结果规律性相符;综合仿真结果和实验数据表明,含B4C 2 %左右的高密度聚乙烯/铅硼复合材料同时具有较好的屏蔽性能和力学性能。     

稀土/高分子复合材料的射线屏蔽性能和磁性能

综述了稀土／高分子复合材料的射线屏蔽性能和磁性能,指出稀土／高分子复合材料在X射屏蔽应用中可有效地弥补铅的弱吸收区,具有高稀土含量的复合高分子屏蔽材料具有强的热中子吸收能力,含稀土的共聚物具有强顺磁性,提出了制备磁性和磁智能稀土／高分子复合材料的可行性。     

中子屏蔽复合材料板材研制及性能研究

以碳化硼（B4C）为吸收材料、高密度低压聚乙烯（HDPE）为基体材料,开展了中子屏蔽复合材料研究。针对辐射屏蔽要求,设计了B4C含量分别为10%、25%、45%3个配方,添加0.2%～0.6%的硅烷偶联剂,改善了B4C的浸润性、分散均匀性以及复合材料的流动性。采用模压-挤出、直接挤出两种工艺,生产出满足核电站乏燃料格板指标要求的复合材料板材,并对其加工性能、力学性能、屏蔽性能的检测方法与影响因素进行了讨论。     

聚合物/碳系填料发泡复合材料电磁屏蔽性能的研究进展

综述了聚合物/碳系填料发泡复合材料在电磁屏蔽领域应用的研究进展,重点讨论了各种碳系填料（石墨烯、碳纳米管、碳纤维）以及多组分碳系填料对发泡复合材料电磁屏蔽性能的影响及相关电磁屏蔽原理。结果表明,碳系填料的功能化、泡孔结构的调控、材料多层次结构的设计、制备工艺的优化等是改善聚合物/碳系填料发泡复合材料电磁屏蔽性能的有效途径。     

石墨/剑麻/聚丙烯电磁屏蔽材料加工性能的研究

采用密炼方式制备石墨包覆爆破剑麻填充聚丙烯(PP)电磁屏蔽材料,研究了该材料的加工性能,具体探讨了不同含量的石墨/剑麻的PP电磁屏蔽材料的力学性能、结晶性能以及毛细管流变性能的变化。结果表明,复合材料的拉伸强度随着填充物含量的增加而降低至23 MPa后基本保持不变;质量分数30%的石墨/剑麻填充物的弯曲性能最好,弯曲模量随着填充物含量的增大而增大;复合材料的结晶和熔融温度随着填充物含量的增大而升高;复合材料的流动性随着填充物含量的增加而变差。     

铁粉/聚丙烯复合材料的电磁屏蔽性能

研究铁粉含量、粒度及偶联剂对铁粉/PP复合材料导电性和电磁屏蔽性能的影响.结果表明:铁粉/PP复合材料的体积电阻率随铁粉质量含量的增加而降低,在20%时出现渗滤值,当铁粉质量含量超过30%之后,继续增大铁粉含量复合材料的体积电阻率和屏蔽效能变化不明显.铁粉含量一定时,随着铁粉目数增大,复合材料的屏蔽效能有所提高;在100MHz～1 GHz低频区域,复合材料最大电磁屏蔽效能达到了40dB.钛酸酯偶联剂为铁粉质量的4%时,能很好地改善铁粉/PP材料的导电性和屏蔽性能.     

功能化碳纳米管/环氧树脂多孔复合材料制备及电磁屏蔽性能

以马来酸酐（MA）为功能性单体,通过自由基反应制备了马来酸酐功能化的多壁碳纳米管（MA-MWCNT）;以MA-MWCNT、环氧树脂、蓖麻油酸改性的四乙烯五胺固化剂、釉粉、水为原料,通过悬浮乳液聚合法制备了功能化碳纳米管/环氧树脂多孔复合材料。采用拉曼光谱、X射线衍射、红外光谱、X射线光电子能谱对功能化的碳纳米管进行了表征和测试。采用扫描电镜（SEM）、表面电阻测量仪、矢量网络分析仪对复合材料的表面形貌、电导率和电磁屏蔽性能进行了测试。结果表明：马来酸酐功能化单体的引入能够很好地改善碳纳米管的分散性能及材料的电磁屏蔽性能;随着碳纳米管含量的增多,复合材料的电导率增大,电磁屏蔽效能峰值增大,材料的电磁屏蔽性能增强;加入功能化的碳纳米管比加入未功能化碳纳米管的电磁屏蔽性能高,多孔复合材料比无孔复合材料的电磁屏蔽性能高。当加入功能化的碳纳米管的量为3%时,制备得到的多孔材料电磁屏蔽性能最佳,其电磁屏蔽性能峰值达到31.1dB。     

碳纳米管填充聚合物基复合体系的电磁屏蔽性能

为防止和减轻电磁波的危害,研制电磁屏蔽材料有重要的实际意义.分别以聚碳酸酯(PC)以及聚碳酸酯/丙烯腈-丁二烯-苯乙烯共聚物(PC/ABS)为基体,以多壁碳纳米管(MWCNT,muliti-walled carbon nanotubes)为主要导电材料,采用熔融法制备填充型复合材料,并对其流变性能和电磁屏蔽效能(SE,shielding effectiveness)进行测试.复合体系在2.5%～3.0%的填充分数内发生了流变逾渗过程.研究制备SE大于35 dB的复合材料,达到民用屏蔽材料的实用标准.     

碳系水泥基复合材料的研究进展

本文介绍了国内外水泥基复合材料的研究进展,重点对水泥基导电复合材料、水泥基电磁屏蔽复合材料和水泥基压电机敏复合材料,如导电性能、磁性能、屏蔽性能、压电性能等材料的组成、特性及发展状况进行了综述.     

基于磁控溅射技术的碳基电磁屏蔽材料

利用磁控溅射技术在碳纤维表面沉积铜膜制备了高效的电磁屏蔽材料,并通过调整磁控溅射时间和碳纤维单向布铺层层数,分析了磁控溅射改性方式和铺层层数对碳纤维织物及其复合材料电磁屏蔽性能的影响。结果表明,磁控溅射碳纤维表面铜膜沉积有利于碳纤维电磁屏蔽性能的改善。经磁控溅射改性处理后,碳纤维电磁屏蔽效能最小提高了37.73%,且电磁屏蔽性能随着磁控溅射时间的延长而增强,但碳纤维电磁屏蔽效能增加率则随磁控溅射时间的增加而逐渐减小。增加碳纤维织物铺层层数有利于碳纤维织物集合体电磁屏蔽性能的改善,但织物层间的不连续性对织物集合体电磁屏蔽性能起消极作用。环氧树脂经碳纤维复合后,电磁屏蔽效能显著增强,增加了约30 dB,但由于环氧树脂对碳纤维的包覆性能,影响了复合材料对电磁波的屏蔽效果,不随碳纤维复合材料中碳纤维织物铺层层数的增加和改性碳纤维导电性能的增加而增强。     

Electromagnetic interference shielding of graphene/epoxy composites

Composites based on graphene-based sheets have been fabricated by incorporating solution-processable functionalized graphene into an epoxy matrix, and their electromagnetic interference (EMI) shielding studies were studied. The composites show a low percolation threshold of 0.52 vol.%. EMI shielding effectiveness was tested over a frequency range of 8.2-12.4 GHz (X-band), and 21 dB shielding efficiency was obtained for 15 wt% (8.8 vol.%) loading, indicating that they may be used as lightweight, effective EMI shielding materials.     

Polyethylene/boron nitride composites for space radiation shielding

Composites made with boron might be absorbers of low energy neutrons, and could be used for structural materials for spacecraft. Polyethylene/boron nitride composites were fabricated using conventional polymer processing techniques, and were evaluated for mechanical and radiation shielding properties. The boron nitride powder surfaces were also functionalized to improve interfacial adhesion. Addition of neat boron nitride to an injection molding grade HDPE increased the tensile modulus from 588 to 735 MPa with 15 vol % filler. The bonding of a trifunctional alkoxysilane to the powder surface prior to processing increases the composite modulus to 856 MPa at the same loading. Scanning electron microscopy of fracture surfaces verified that the silane‐treated powders had improved adhesion at the filler/polymer interface. Radiation shielding measurements of a 2 wt % boron nitride composite were improved over those of the neat polyethylene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Electromagnetic interference shielding mechanisms of CNT/polymer composites

The electromagnetic interference (EMI) shielding mechanisms of multi-walled carbon nanotube (MWCNT)/polymer composites were analyzed experimentally and theoretically. For the experimental analysis, EMI shielding effectiveness (SE) of MWCNT/polypropylene (PP) composite plates made in three different thicknesses and at four different concentrations were studied. A model based on the shielding of electromagnetic plane wave was used to theoretically study the EMI shielding mechanisms. The experimental results showed that absorption is the major shielding mechanism and reflection is the secondary shielding mechanism. The modeling results demonstrated that multiple-reflection within MWCNT internal surfaces and between MWCNT external surfaces decrease the overall EMI SE. The EMI SE of MWCNT/PP composites increased with increase in MWCNT content and shielding plate thickness.     

Study on the graphite nanosheets/resin shielding coatings

Shielding coatings based on graphite nanosheets were prepared by compounding method. The surface morphology of the graphite nanosheets and conductive coatings was examined by scanning electron microscopy. The surface resistivity of the coatings was greatly declined by incorporating the graphite nanosheets. The electromagnetic interference shielding effectiveness (SE) from 0.3 MHz to 1.5 GHz was also studied, and found that the SE of the coatings was consistent with its conductivity. The best sample was shown to exhibit up to 38 dB of SE at 1.5 GHz (with a thickness of 400 μm). The main shielding mechanism of the system was reflection and multiple reflections.     

Electromagnetic interference shielding of graphite/acrylonitrile butadiene styrene composites

Dispersion of graphite within the acrylonitrile butadiene styrene matrix demonstrates enhanced electromagnetic interference shielding of composites through the use of tumble mixing technique. A shielding effectiveness of 60 dB with 15 wt % of graphite has been achieved. D shore hardness data revealed a little decrease in hardness of composites with rise in graphite content. DC conductivity measurements revealed a fairly low percolation threshold at 3 wt % of graphite. The conductivity exhibited by 15 wt % composite is 1.66 × 10⁻¹ S/cm. These composites are fit for use as an effective and convenient EMI shielding material because of easy processing, better hardness, light weight, and, reasonable shielding efficiency. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011