Comparison of YAG: Eu phosphors synthesized by supercritical water in batch and continuous reactors

Luminescent yttrium aluminum garnet (YAG, Y₃Al₅O₁₂) nanoparticles doped with Eu (10 at%) were synthesized in batch-type and continuous-type supercritical water (SCW) reactors. In the case of the continuous-type SCW method, the particles of YAG: Eu phosphors were much smaller and demonstrated a uniform spherical-like shape. Inversely, in the case of the batch-type SCW method, a needle-like or elliptical-like shape was formed because a finite amount of time was required to reach SCW conditions from ambient conditions. However, the emission intensity of YAG: Eu phosphors synthesized by using the batch-type SCW method was stronger. Therefore, it is concluded that the continuous-type SCW method is superior to the batch-type SCW method from the viewpoint of the particle size and shape, but the luminescence property of phosphors in the continuous-type SCW method needs to be improved. In addition, a calcination process slightly improved the luminescence intensities of YAG: Eu phosphors generated by using either the batch-type or continuous-type SCW methods.     

Phase inversion and its effect on the properties of polyester polyurethane cationomers

Polyester polyurethane cationomers are prepared using polyester polyol of molecular weight 2000 as soft segments, N-methyl diethanolamine as chain extender, glycolic acid as quaternization agent, methyl ethyl ketone as solvent, and 4,4'-diphenylenemethylene diisocyanate (MDI) as diisocyanate. Properties of the films cast from solutions and emulsions are studied by infrared spectroscopy, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and tensile-elongation testing. Ionization can cause phase separation and produces increased cohesion in the hard domains. The dispersion process can be divided into three stages involving a separation of hard segment aggregates due to adsorption of water on their surface, water entering into hard segment microionic lattics, and finally a rearrangement of agglomerates to form microspheres. The dispersion can disrupt the order in the hard domains and an increased phase separation.     

纳米载体铜基催化剂对低碳醇合成的影响

本文用沉积-沉淀法制备了新型纳米载体低碳醇合成催化剂，并与共沉淀法所制备的催化剂进行了对比，结果表明，纳米载体催化剂活性高、耐热性能好、醇收率高纳米载体对纳米载体催化剂活性大小的影响顺序为：纳米Al2O3＞纳米ZnO-ZnAl2O4＞纳米MgAl2O4＞纳米MgO.工艺参数对反应性能的影响结果表明，反应温度低，甲醇选择性高；但温度太高（＞320℃）CO2。选择性升高，且整个反应为动力学控制；压力升高可提高活性和C1-C2OH选择性，但C4OH选择性下降；结合空速对产物分布的影响，反应可能按Smith和Anderson的缩聚机理进行．     

PVC/NE复合材料的结构流变学及力学性能

采用熔融共混法制备了聚氯乙烯/霞石复合材料(PVC/NE),并测试了其形态、结构流变学和力学性能。结果表明,NE用量存在最佳值,用量过多对复合材料介观结构的贡献不大;NE均匀分散在PVC基体中,且用量约为50phr时,复合材料的冲击强度和表面硬度最佳。     

机械力化学改性硅灰石/聚丙烯性能的研究

利用气流磨对硅灰石进行机械力化学改性，并用IR分析对改性效果进行了预评价；对比了用改性前后的硅灰石填充聚丙烯(PP)的性能。结果表明：改性后硅灰石分别为由亲水疏油性变为亲油疏水性；硬脂酸质量分数为1．5％时，改性硅灰石／PP复合材料的拉伸强度和冲击强度最好。     

原位聚合改性交联LLDPE介电性能的研究

利用原位聚合聚丙烯酸钠(PNaAA)改性交联聚乙烯,增加聚乙烯的极性。采用FTIR和DSC表征了原位聚合后交联聚乙烯的结构形态。讨论了PNaAA、DCP用量对体系力学性能、介电性能的影响,结果表明:随着PNaAA用量的增加,体系拉伸强度略有增加,断裂伸长率下降,体积电阻率随PNaAA用量增加而变小;随着DCP用量的增加,拉伸强度出现一个最大值后开始下降,体系断裂伸长率随DCP用量的增加而下降。从体系组成及分子结构方面分析了介电性能随PNaAA用量增加而变化的原因。     

低阻PTC陶瓷材料的研究

本研究采用传统的固相反应工艺，以国产工业级化工原料，掺杂施主元素Nb、La、Y、Tn以及显微结构调节剂BN和ASTL相，通过实验探讨了低阻PTC陶瓷材料的配方组成、工艺制度对材料电性能的影响，成功制备出性能良好的低阻PTC陶瓷材料。     

高密度聚乙烯／聚碳酸酯共混体系性能的初步研究

本文介绍发不同牌号高密度聚乙烯和聚碳酸酯对ＨＤＰＥ／ＰＣ共混物性能的影响结果。同时以ＰＥ接枝马来酸酐和自ＰＥ接枝烯丙基双酚Ａ醚及ＰＥ接枝烯丙基双酚Ａ作为增容剂，研究了不同增容剂、ＰＣ含量和增容剂含量对ＨＤＰＥ／ＰＣ共混物力学和热性能的影响。     

Effect of SiCnws on flexural strength of SiCf/HfC-SiC composites after impact and ablation

SiC nanowires (SiC_nws) modified SiC_f/HfC-SiC composites were prepared by precursor infiltration and pyrolysis (PIP) and chemical vapor infiltration (CVI) methods. The microstructure, flexural strengths, impact and impact-ablation tests of the composites with and without SiC_nws were investigated. The results showed that after introducing SiC_nws, not only the retention rate of HfC ceramic produced by PIP was increased obviously, but also the fracture displacement of the modified composites was reduced due to the enhancement effect of SiC_nws at interface between SiC fiber and matrix. After impact and impact-ablation, the strength retention of SiC_nws modified composites was 91.6 % and 69.1 % respectively, higher than that of the composites without SiC_nws (85.2 % and 54.8 %). As the impact resistance of the modified composites was improved by the pull-out and bridging of SiC_nws, the ablation resistance of the impacted composites was enhanced as well.     

粉末冶金法浸入式发泡制作泡沫铝的试验研究

研究了浸入法制备泡沫铝的发泡新工艺以及工艺参数对发泡效果的影响，得出以工业纯铝粉和而H2粉为原料，制备气泡均匀、孔隙可控的泡沫铝的工艺参数为：浸入温度为680～760℃，浸入时间为10～30s，保温发泡时间为10～60s。研究结果表明，粉末冶金法浸入式发泡制备泡沫铝的效果好、结构均匀、TiH2利用率高，是一种有较好开发前景的新制备方法。