Recent advance in research on halloysite nanotubes-polymer nanocomposite

Halloysite nanotubes (HNTs) are novel 1D natural nanomaterials with predominantly hollow tubular nanostructures and high aspect ratios. Due to their high mechanical strength, thermal stability, biocompatibility, and abundance, HNTs have a number of exciting potential applications in polymer nanocomposites. In this article, we review the recent progress toward the development of HNTs-polymer nanocomposites, while paying particular attention to interfacial interactions of the nanocomposites. The characteristics of the HNTs relative to the formation of the polymer nanocomposites are summarized first. The covalent or non-covalent functionalization methods for HNTs and various fabrication approaches for HNTs-polymer nanocomposites are introduced afterward. Polymer nanocomposites reinforced with HNTs possess highly increased tensile and flexural strength, elastic moduli, and improved toughness. HNTs-polymer nanocomposites also exhibit elevated thermal resistance, flame retardance and unique crystallization behavior. Due to the tubular microstructure and the biocompatibility of HNTs, HNTs-polymer nanocomposites have demonstrated good drug encapsulation and sustained release abilities, gaining them extensive use as tissue engineering scaffolds and drug carriers. Finally, we summarize the characteristics of HNTs-polymer nanocomposites and predict for the development of the potential applications in high-performance composites for aircraft/automobile industries, environmental protection, and biomaterials.     

Effects of mesoporous silica particles on the emulsion polymerization of methyl methacrylate

Rod‐like and spherical mesoporous SBA‐15 silica particles were synthesized as pure silicas and surface modified by organosilane coupling agents firstly, and then the effects of these mesoporous materials on the critical micelle concentration (CMC) of sodium dodecylsulfate (SDS), the stabilities of batch and semi‐continuous MMA emulsion polymerizations, and the molecular weights and molecular weight distributions of the polymer products were studied. The incorporation of both unmodified and silane‐modified forms of the mesoporous silica particles in the polymerization reaction increased the CMC of SDS. The presence of the unmodified mesoporous silica in the polymerization process led to instability in the batch emulsion polymerization process, as indicated by the formation of increased amounts of coagulum, and a decrease in the molecular weight of the polymer product. However, in comparison to the polymer formed in the absence of particle additives the molecular weight of the PMMA polymer increased with the amount of emulsifier and the addition of silane‐modified SBA‐15 particles, suggesting the growth of the polymer chains is facilitated at least in part by reaction in the pores of the particles. The improvement in molecular weight indicates that semi‐continuous MMA emulsion polymerization is best suited for the preparation of PMMA–mesoporous silica composites. POLYM. ENG. SCI., 54:2746–2752, 2014. © 2013 Society of Plastics Engineers     

地方高校材料大类复合型人才培养模式研究与探索

地方高校材料大类专业复合型人才培养是实现材料大类专业的可持续性发展和为地方经济发展服务的重要保障。文章从课程体系、实践教学体系、师资队伍建设和创新能力培养等方面对材料大类专业的复合型人才培养模式进行了系统的研究与探索。     

新钢10~#高炉优化高炉操作的生产实践

为稳定炉况,改善高炉操作指标,新钢10~#高炉进行了优化操作实践,取得了较好的效果。     

Transformation of induction heating deposited monetite coating to hydroxyapatite coating on HT-C/C composites by hydrothermal treatment in two types of solution

Monetite coatings on H₂O₂-treated carbon/carbon composites were prepared by induction heating deposition method and then converted to HA coatings by hydrothermal treatment in an autoclave with two different types of solutions, respectively NaOH aqueous solution and ammonia solution. The structure, morphology and chemical composition of the as-achieved HA coatings were characterized by XRD, FTIR SEM and EDS. The adhesion of HA coatings to the HT-C/C substrates was evaluated by a scratch test. The results showed that there are no obvious changes in the structure and morphology for the as-achieved HA coatings except to their compositions. The average critical load of the ammonia hydrothermally treated HA coatings is 10.9 N, while the NaOH hydrothermally treated HA coatings show the average one of 51 N, and the reason for it was suggested.     

Dielectric and microwave absorbing properties of low power plasma sprayed Al2O3/Nb composite coatings

Al₂O₃/Nb composite coatings were sprayed on graphite substrates by low power atmospheric plasma spraying (LPAPS) with an internally fed powder torch. The composite particles were agglomerated with different mass fractions by spray-drying technology. The microstructure and dielectric properties of coatings were investigated. The microstructure of composite coatings shows a uniform dispersion of metal particles in the composite coatings. Both the real (?′) and imaginary (?″) parts of the complex permittivity increase with increasing Nb content over the frequency range of 8.2-12.4 GHz, which is ascribed to space charge polarization and conductance loss, respectively. By calculating the microwave-absorption as a single-layer absorber, reflection loss values exceeding −10 dB can be obtained in the frequency range of 10.0-11.8 GHz with 10 wt% Nb content coating when the coating thickness is 1.5 mm.     

丙烯腈反应器新型两级旋风分离器大型冷模试验研究

针对丙烯腈装置扩能的要求 ,分析了用新型两级旋风分离器取代原三级旋风分离器的必要性 ,采用PV型和PV E型旋风分离器组成新型两级旋风分离器。根据旋风分离器尺寸分类优化设计法 ,设计了一种工业尺寸规模的两级旋风分离器 ,并将它和Ducon型三级旋风分离器在冷态条件下进行了对比试验。结果表明 ,新型两级旋风分离器不仅性能优异 ,而且结构简单、占据空间小、工作可靠 ,适合现有丙烯腈装置扩能改造的需要。     

Cr粒子含量对Al2O3/Cr复合材料力学性能及介电性能的影响

以热压烧结的方法制备了Al2O3／Cr复合材料，探讨了Al2O3／Cr复合材料显微结构、力学性能及微波介电性能随Cr粒子含量变化的规律。SEM结果表明，在垂直于压力方向上，Cr粒子有明显的受压拉伸现象；当Cr粒子含量从10vol％增加至30vol％时，复合材料中Cr粒子的分布由孤立向桥连方式转变。随Cr粒子含量的增加，复合材料致密度略有下降，抗弯强度明显降低。与纯氧化铝陶瓷相比，含10vol％Cr粒子Al2O3／Cr复合材料的断裂韧性提高了81％以上。复介电常数测试结果表明，在8．2～12．4GHz频率范围内，复合材料复介电常数的实部和虚部随Cr粒子含量的增加大幅度上升，且存在明显的频散效应。当Cr粒子含量达到30vol％时，由于Cr粒子之间的部分桥连现象而使介电常数虚部在一定频段出现负值。     

我国对流层波导环境特性研究

描述了我国对流层波导环境特性研究的方法和结果。对于我国陆上大气波导，详细介绍了波导气侯区的划分结果和这些地区大气波导随季节和月份的变化情况。重点描述了我国海上蒸发波导的研究方法和研究结果，在叙述了利用海面气象数据得到我国海上蒸发波导特性参数的理论方法之后，说明了我国东海和南海的海区划分，给出了这些海区蒸发波导出现的概率、波导高度、强度的年际变化情况。