EPDM/PS交替多层复合材料的力学性能分析

用自行设计的微纳多层共挤出体系制备了三元乙丙橡胶/聚苯乙烯(EPDM/PS)交替多层复合材料。偏光显微镜和扫描电镜分析表明, 所制备的复合材料具有规则层状交替结构。与同组分的一般共混样品相比, 64层EPDM/PS交替复合材料表现出不同的拉伸断裂行为: 初期的PS断裂行为和后期的EPDM拉伸行为。EPDM和PS层保持了较好的连续性, 且EPDM层阻止了PS层裂纹向相邻PS层的发展, 使64层样品与同组分的一般共混样品相比具有较高的拉伸强度和杨氏模量。讨论了在PS相中加入相容剂苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS)对64层EPDM/PS交替复合材料力学性能的影响, 发现SEBS的加入提高了PS相的韧性, 并且改善了EPDM层与PS层界面的相互作用。      

Ge nano-layer fabricated by high-fluence low-energy ion implantation

A Ge nano-layer embedded in the surface layer of an amorphous SiO₂ film was fabricated by high-fluence low-energy ion implantation. The component, phase, nano-structure and luminescence properties of the nano-layer were studied by means of Rutherford backscattering, glancing incident X-ray diffraction, laser Raman scattering, transmission electron microscopy and photoluminescence. The relation between nano-particle characteristics and ion fluence was also studied. The results indicate that nano-crystalline Ge and nano-amorphous Ge particles coexist in the nano-layer and the ratio of nano-crystalline Ge to nano-particle Ge increases with increasing ion fluence. The intensity of photoluminescence from the nano-layer increases with increasing ion fluence also. Prepared with certain ion fluences, high-density nano-layers composed of uniform-sized nano-particles can be observed.     

Synthesis of SiC/SiO2 core–shell powder by rotary chemical vapor deposition and its consolidation by spark plasma sintering

SiC (core) and SiO₂ (shell) powders were synthesized via rotary chemical vapor deposition (RCVD). The SiC particles (3C, <1 μm in diameter) were coated with a layer of SiO₂ (10–15 nm in thickness). Using spark plasma sintering, the SiC/SiO₂ nanopowders were then synthesized into SiC/SiO₂ composite bodies. Although a phase transformation from 3C to 6H was observed at above 2123 K in the sintered monolithic SiC bodies, sintered SiC/SiO₂ bodies did not display such phase transformation. In addition, SiC/SiO₂ bodies did not exhibited grain growth until the sintering temperature reached 2223 K. The density and Vickers hardness of the sintered SiC/SiO₂ bodies increased with increasing sintering temperature. The highest density and hardness of SiC/SiO₂ composite bodies were 98.1% and 24.4 GPa at 2223 K, respectively, which were higher than the corresponding values of 90% and 14 GPa for monolithic SiC bodies.     

微纳多层功能复合材料的制备新技术

介绍了微纳多层共挤出技术是通过简单地对高分子熔体进行分割-变流-合并过程来增加层数的技术。说明通过微纳多层共挤出技术制得的微纳交替多层复合材料在结构上不同于传统加工方法制得的复合材料,其力学性能、阻隔性能、导电性能、光学性能具有独特的优点。指出微纳多层共挤出技术还可用于开发新型的中间相材料;这种交替多层结构形态为界面张力、粘接、结晶、扩散等理论研究提供了一个很好的模型。     

微纳米木质素颗粒在酸碱溶液中的溶解行为

通过测试粒径,研究了具有微纳米尺寸的木质素颗粒在酸碱溶液中的溶解行为。结果显示:木质素在碱性溶液中的溶解无规律,但在酸性溶液中的溶解却首先是溶胀然后才是溶解,而这两者的分水岭似乎是在80min(25℃条件下),与酸液浓度无关。但值得关注的是这两者引起木质素颗粒的外型从球状改变为长方体。红外光谱显示木质素在酸性溶液中的溶解主要是其芳香环的断裂即分子量降低而无结构变化。