不同密度的尼龙12/钨屏蔽复合材料的流变及使用性能

通过改变钨(W)的含量,采用熔融共混、注射成型的方法制备了不同密度的尼龙(PA)12/W屏蔽复合材料,利用熔体流动速率仪、冲击试验机、计算机断层扫描仪研究了PA12/W屏蔽复合材料的流变、冲击及屏蔽性能。结果表明,密度低于11.0 g/cm3时,复合材料熔体为假塑性流体,其中密度为11.0 g/cm3的复合材料的剪切速率对其熔体黏度的影响最小,因而最适于注射成型;随密度的增加,复合材料冲击强度逐渐降低,CT值和对X射线的衰减率逐渐升高,当密度为11.0 g/cm3时,复合材料的冲击强度为24 kJ/m2,CT值达到17500左右,已接近铅的CT值,对X射线的衰减率为97%。综合流变、冲击及屏蔽性能,优选密度为11.0 g/cm3的PA12/W屏蔽复合材料应用于X射线屏蔽制品的生产。     

HDPE/木粉复合材料的性能研究

研究了不同种类的增容剂对高密度聚乙烯(HDPE)木/粉复合材料性能的影响,并研究了增容剂含量、木粉含量对复合材料力学性能及形态结构的影响。结果表明,HDPE木/粉复合材料的拉伸强度、弯曲强度均随马来酸酐接枝HDPE(HDPE-g-MAH)含量的增加而增大;复合材料的缺口冲击强度随甲基丙烯酸缩水甘油酯接枝低密度聚乙烯的增加而提高;复合材料的拉伸强度、弯曲强度随木粉含量的增加而增大;而缺口冲击强度则随木粉含量的增加呈降低趋势。     

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。     

木粉粒径对木塑复合材料性能的影响

采用不同粒径的木粉填充高密度聚乙烯制备木塑复合材料，研究了木粉粒径对木塑复合材料力学性能和加工流动性的影响。结果表明：木粉粒径对复合材料性能的影响十分明显，较大粒径的木粉有利于复合材料弯曲性能和冲击强度的提高。木粉粒径从100μm增加到850μm，复合材料弯曲强度增加10．4％，弯曲模量增加56．3％，冲击强度增加14．6％。随木粉粒径的增大，拉伸强度呈现先上升后下降的趋势，在200μm时出现最大值。木粉粒径对熔体流动速率（MFR）和密度的影响十分明显，大粒径的木粉使复合材料具有较高的MFR和较低的密度。     

纳米CaCO_3对PE–HD/CF复合材料力学性能的影响

针对高密度聚乙烯(PE–HD)/碳纤维(CF)二元复合材料随CF含量的增加,拉伸强度和弯曲强度增大、冲击强度却逐渐下降的情况,在二元体系中添加纳米CaCO3制得PE–HD/CF/CaCO3三元复合材料,对比分析了两种复合材料的力学性能,并采用扫描电子显微镜对三元复合材料的冲击断面进行观察。结果表明,纳米CaCO3的加入使得三元复合材料的拉伸强度略有降低,但弯曲强度和冲击强度在一定范围内增大;当纳米CaCO3含量为10份时,复合材料的综合力学性能最佳。     

粉煤灰空心玻璃微珠填充高密度聚乙烯的性能

采用从粉煤灰中提取的空心玻璃微珠,制备不同空心玻璃微珠含量的高密度聚乙烯复合材料,研究空心玻璃微珠对复合材料力学性能和结晶性能的影响.结果表明:随着空心玻璃微珠含量的增加,复合材料的拉伸强度逐步增大,弯曲强度和冲击强度先增大后减小,当空心玻璃微珠质量含量为5%时,弯曲强度和冲击强度达到最大.适量空心玻璃微珠的加入对复合材料的结晶性能有一定程度的改善.     

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。     

改性铝塑膜回收料/MWCNT复合材料的制备及性能研究

以高密度聚乙烯(HDPE)改性的铝塑膜回收料为基础原料,通过熔融共混的方式制备了铝塑膜改性料/多壁碳纳米管(MWCNT)复合材料。首先以乙醇和水的混合溶液作为溶剂,用硅烷偶联剂KH560对MWCNT进行表面处理,通过红外光谱、扫描电镜对改性MWCNT的结构进行表征,红外数据表明MWCNT表面成功引入了硅烷偶联剂分子。考察了MWCNT含量对复合材料力学性能、流变性能及电磁屏蔽性能的影响。结果显示:复合材料的弯曲强度、拉伸强度及缺口冲击强度均随MWCNT含量的增加呈现先增大后减小的趋势。加工流动性随MWCNT含量的增加呈逐渐降低的趋势。体积电阻率随MWCNT含量增加逐渐降低,电磁屏蔽效能逐渐升高。当MWCNT的含量为8%时,复合材料的体积电阻率为5.3×10~5Ω·cm,主体电磁屏蔽效能达到了20～30 dB。     

PE-HD/CF/HGB三元复合材料的制备及力学性能

以高密度聚乙烯(PE-HD)为基体、碳纤维(CF)为增强材料,采用双辊塑炼工艺制备了PE-HD/CF复合材料,力学性能测试结果表明该复合材料的拉伸和弯曲性能随CF含量的增加而增大,但缺口冲击强度逐渐下降。在该复合材料基础上添加空心玻璃微珠(HGB)制得PE-HD/CF/HGB三元复合材料,力学性能测试结果表明当HGB用量为10份且CF用量为15份时,三元复合材料的拉伸强度、弯曲强度和缺口冲击强度均达到最大,分别为46.98 MPa,45.69 MPa和8.17 kJ/m2,较未加HGB的PE-HD/CF复合材料分别提高了7.19%,4.17%和10.4%。扫描电子显微镜结果表明,HGB主要通过其变形和破坏来吸收冲击能量,从而提高复合材料的韧性。     

高钨含量尼龙6复合材料X射线屏蔽性能研究

利用计算机断层扫描(CT)仪对高钨含量尼龙6复合材料的X射线屏蔽性能进行了研究.结果表明:该尼龙6复合材料对X射线屏蔽性能随密度、厚度增大而提高,同时遵守朗伯-比耳定律;密度为10.3g/cm3的尼龙6复合材料具有与铅近似的屏蔽效果.     

Microstructure and properties of WB/Al nuclear shielding composites prepared by spark plasma sintering

In this paper, a novel nuclear shielding material capable of shielding neutrons and gamma rays, WB-reinforced Al (WB/Al) composites, was prepared by spark plasma sintering (SPS) process. The microstructure of the composites was characterized, and the effects of WB content, heat treatment and matrix type on the properties of the composites were discussed. The results demonstrate that the WB particles are uniformly dispersed in the aluminum matrix and formed a good binding interface with the matrix. WAl₁₂ as an interfacial reaction product is identified, and segregation of Si and Mg elements at the reinforcement/matrix interface occurs. The mechanical properties of the WB/Al composites are sensitive to the WB content. The hardness, elastic modulus and bending strength of the composites increase monotonously as the WB volume fraction increasing, up to 234%, 107% and 91.6% higher respectively than those of the monolithic 6061Al. However, the tensile strength reaches a peak point when the volume fraction is 20%. The effects of T6 treatment and matrix type are not pronounced, especially for the composites with high WB content. The thermal neutron and gamma ray shielding properties of the composites both increase with the increase of material thickness and WB content. The WB/Al composites developed in this work show good application prospects in the field of nuclear radiation protection, due to their good mechanical properties and well neutron and gamma-ray shielding performance.     

高填料、超厚防辐射屏蔽材料的研制

以富氢聚乙烯为基材,通过加入高填充量的中子吸收剂--硼化合物来制备高填料、超厚防辐射屏蔽材料。研究了聚乙烯熔体流动速率、碳化硼及氧化钆含量对防辐射屏蔽材料力学性能和屏蔽性能的影响,并探讨不同成型工艺对材料性表观性能的影响。结果表明,选用高熔体流动速率的高压低密度聚乙烯粉料及同等粒径的硼化合物作为填料,通过工艺条件设置和模具改进,能够制备出力学性能优异、内外观质量俱佳的高填料、超厚防辐射屏蔽材料,其中子屏蔽（削弱）系数大于6,伽玛屏蔽（削弱）系数大于8。     

Effect of CdO addition on photon,electron, and neutron attenuation properties of boro-tellurite glasses

This research article aims to study the effect of CdO addition on the radiation shielding characteristics of boro-tellurite glasses in the composition of 50B₂O₃ - (50-x) TeO2- xCdO, where x = 0, 10, 20, 30, 40 and 50 mol%. These glasses were exposed to gamma radiation and the transmitted gamma photons were evaluated for energies varying from 15 keV to 15 MeV using Geant4 simulation toolkit. The number of transmitted photons was then used to characterize the gamma shielding for the studied glasses in terms of linear/mass attenuation coefficients, MFP, Z_eff, and HVL. The simulation outcomes were theoretically confirmed by using Phy-X software. The beta (electron) shielding characterization of the involved glasses was also investigated by determining the projectile range and stopping power using ESTAR software. Additionally, the fast neutron shielding characterization of the glasses was achieved by evaluating removal cross-section (Σ_R). The results reveal that the CdO has a small influence on the shielding performance of the boro-tellurite glasses against gamma, beta, and neutron radiations. The shielding performance of the boro-tellurite glasses was compared with that of common shielding materials in terms of MFP. It can be concluded that the boro-tellurite glasses regardless of the concentration of CdO content have promising shielding performance to be used for radiation applications.     

Developing a radiation shield and investigating the mechanical properties of polyethylene-polyester/CdO bilayer composite

Radiation attenuation and mechanical properties are two key parameters for shielding in space. This study explored the attenuation parameters of cadmium as a popular filler for the shielding of thermal neutrons in the unsaturated polyester (UPS) polymer matrix. The polyester matrix was used for the first time. The composite behavior against gamma radiation (by applying Cs-137 radioisotope, E gamma = 0.662 MeV) was evaluated using the gamma spectrometer. Also, the sample was exposed to neutron radiation by utilizing a²³⁹Pu–Be neutron source. The effect of the composite sample produced with the cadmium filler was also examined when exposed to gamma radiation. Further, the attenuation parameters of the gamma rays were studied. The observations indicated the suitable shielding of this composite for thermal neutrons, such that the half-value layer (HVL) decreased from 7.8 cm in the polyester sample to 0.22 cm in the polyester/10 wt% CdO composite sample. The linear attenuation coefficient of the thermal neutron increased from 0.0888 (cm^-1) in the polyester sample to 3.15 (cm^-1) in the 10 wt% CdO composite sample, thus indicating more than 35-fold improvement in the neutron attenuation. Composite samples were exposed to gamma radiation; contrary to the expectations, the results showed an almost twofold improvement in the attenuation of gamma radiation, as compared to the polyester sample. This composite specimen was coupled to a 2 mm thick linear low-density polyethylene (LLDPE) layer for the better shielding of thermal neutrons. Finally, the composite sample was mechanically reinforced with a silica glass fiber, which enhanced the ultimate tensile strength (UTS) from 39 to 298 MPa. Also, the elongation rate (% E) was raised from 6% in the polyester sample to 10.5% in the polyester/10 wt% CdO- silica glass fiber sample. Thus, the results indicated the production of a strong composite capable of attenuating neutron and gamma radiation. Accordingly, this composite could be considered a reliable option for use as a shield in space missions.     

可快速固化、阻燃聚氨酯复合屏蔽材料的制备及性能

针对核设施退役过程中可能存在对设施内部放射性预估不当而导致在解体去污过程中辐射量超标的紧急情况,采用实验室一步成型法制备了一种可快速固化的阻燃聚氨酯复合屏蔽材料,研究了屏蔽填料(氧化钨)及阻燃填料(硼酸锌)的总含量对材料固化时间、微观结构、密度、压缩强度、阻燃性能及屏蔽性能的影响。结果表明,双组分聚氨酯混合体系的乳白时间受填料含量变化的影响较小,而表干时间随填料含量增大先减小后增大,但仍保持较快的固化速度;填料主要分布在泡孔孔壁中,随着填料含量的增加,材料的泡孔逐渐细化;材料的密度随填料含量增加逐渐变大而压缩强度逐渐减小;极限氧指数随着硼酸锌含量增加逐渐提高;不同γ射线能量下射线的透射率随填料含量增加逐渐减小,但是随着射线能量增强材料屏蔽性能逐渐减弱,在相同能量下,增加材料的厚度可以有效改善其屏蔽性能。当氧化钨和硼酸锌质量分数分别为40%和20%时,该新型复合屏蔽材料具有较短的固化时间和较好的阻燃及力学性能,在中低能射线辐照下具有较好的屏蔽性能,其在应对核电站退役过程中保障工作人员辐照安全方面具有较大的应用前景。     

Fine-grained and electrically conductive NdB6/SiO2: A promising electromagnetic interference shielding material with good thermal and mechanical properties

Searching for thermal conductive materials with high electromagnetic interference (EMI) shielding effectiveness (SE) is the key to protect electronic equipment against electromagnetic pollution and excess heat emission. Herein, NdB₆/SiO₂ bulks with high EMI SE and thermal conductivity which also exhibit good mechanical properties were prepared by liquid phase sintering (LPS). The NdB₆/SiO₂ bulk prepared by LPS at 1550 °C has fine grain-size, which is beneficial to improving mechanical property and EMI shielding performance. It exhibits high conductivity of 1.47 × 10⁴ S/cm, high EMI SE of 55.1 dB in K band, and high thermal conductivity of 37.9 W/m K. It also possesses flexural strength of 266 MPa and Vickers hardness of 14.8 GPa. Thus, NdB₆/SiO₂ composite ceramics are promising candidates for EMI shielding with good heat dissipation and mechanical load-bearing capabilities.     

Microcellular Conductive Carbon Black or Graphene/PVDF Composite Foam with 3D Conductive Channel: A Promising Lightweight,Heat-Insulating,and EMI-Shielding Material

In this study, a lightweight microcellular carbon-based filler/poly(vinylidene fluoride) (PVDF) composite foam is fabricated with a 3D conductive network that is thermally insulating, electrically conductive, and fabricated on a large scale. This composite can be used for high-efficiency thermal insulation and electromagnetic interference (EMI) shielding applications. The prepared composite demonstrates low density, high electrical conductivity, and excellent thermal insulation properties. The structure and density of the conductive network and the carbon-based filler content has a significant influence on the electrical conductivity of the prepared composite foam. Although the composite comprises microcellular PVDF beads of the same density, the conductivity of the composite-comprising strip beads is greater than that comprising spherical beads. In the same conductive network structure, as the size of the microcellular PVDF beads decrease, the conductive network becomes denser, which results in a higher conductivity. Furthermore, with an increase in the conductive filler content, the conductivity improves significantly. Excellent EMI shielding materials with optimal filler content and particle shapes, exhibiting EMI shielding effectiveness of up to 40–50 dB, are developed. The prepared composite foam possesses excellent application potential in the fields of ultra-light thermal insulation, conductivity, and EMI shielding.     

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。     

Processing and properties of boron carbide (B4C) reinforced LDPE composites for radiation shielding

In the present work, boron carbide (B₄C) particles were synthesized with sol-gel technique following with heat treatment at 1500 °C in an argon atmosphere. 3-(Triethoxysilyl)-propylamine, a silane coupling agent, was doped on to the surface of synthesized B₄C particles. The surface modified B₄C particles were embedded in LDPE matrix in order to obtain flexible, lightweight and environmentally friendly shielding materials. The effect of surface functionalization and concentration of boron carbide on its distribution characteristics in the polymer matrix and its effects on the mechanical and neutron shielding properties of the composites are examined. The results showed that high purity-fully crystalline B₄C powders with polyhedral-equiaxed morphology in the size range of 20 nm–500 nm were produced. It was found that even the very low amount (0.6–1.7 wt%) of incorporated nano/sub-micron B₄C particles in LDPE matrix improved the neutron shielding (up to 39%), tensile strength (9.3%) and impact resistance (8%) of the composites.