PEO／Na-MMT粉体与聚氯乙烯复合材料的制备及性能研究

通过溶胶-凝胶法，制备了聚氧乙烯（PEO）和钠基蒙脱土的复合粉体PMMT，经XRD和透射电镜分析，蒙脱土在聚氯乙烯中基体进行了纳米级的分散：通过对材料力学性能、毛细管流变和TGA测试表明，PMMT对聚氯乙烯具有增韧和增强的效果，同时使PVC的流变性和热稳定性也有一定的提高。     

PA6/季膦盐改性MMT纳米阻燃复合材料的制备及性能研究

首先采用十六烷基三苯基溴化磷改性处理后的蒙脱土(PMMT)与己内酰胺原位聚合,制得聚酰胺6(PA 6)/PMMT纳米复合材料,然后加入三聚氰胺焦磷酸盐(MPP)/季戊四醇(PER)/聚磷酸铵(APP)复合阻燃体系(cMPA),采用熔融共混的方式制备了PA 6/PMMT/cMPA纳米阻燃复合材料,考察了复合材料的阻燃性能...     

聚氯乙烯／蒙脱土复合材料的结构与性能研究

采用熔融共混法制备了聚氯乙烯／蒙脱土复合材料。通过X射线衍射和透射电镜对复合材料的结构进行了表征。研究了钠基蒙脱土和有机铵盐改性的有机蒙脱土对聚氯乙烯／蒙脱土复合材料的结构、力学性能和流变性能的影响。     

聚氯乙烯／蒙脱土纳米复合材料的制备与性能

对钠基蒙脱土进行有机化处理,XRD表明有机阳离子已同钠离子发生离子交换。熔融法制备聚氯乙烯／蒙脱土插层复合材料,用X－射线衍射研究复合材料的结构,聚氯乙烯不能插层于钠基蒙脱土,但能插层于有机蒙脱土,形成剥离型纳米复合材料。采用DSC研究了聚氯乙烯／有机蒙脱土复合材料的玻璃化转变温度,研究结果表明,聚氯乙烯／有机蒙脱土比聚 乙烯／钠基蒙脱土复合材料的力学性能优异。     

PBC/PLA复合材料及其静电纺丝膜的制备与表征

采用双螺杆挤出机熔融共混改性聚碳酸丁二醇酯/聚乳酸(PBC/PLA),并加入成核剂磷系蒙脱土(PMMT)和凹凸棒土,研究了成核剂对共混物结晶性能的影响。采用傅立叶红外分析(FITR)和扫描电镜(SEM)对材料的结构进行表征,通过差示扫描量热法(DSC),热重分析(TG)研究了添加剂对共混材料的结晶性能及热稳定性的影响。结果表明,随着成核剂PMMT添加量的增多,热失重的温度明显降低,加入凹凸棒土成核剂的复合材料的热失重没有明显的变化,但凹凸棒土对共混物的结晶速度影响比较大,对结晶速度有很好的促进作用。     

聚氯乙烯/蒙脱土纳米复合材料研究进展Ⅰ制备原理及表征方法

对插层法制备聚氯乙烯／蒙脱土纳米复合材料的国内外的研究现状作了简要的回顾,并对聚氯乙烯／蒙脱土纳米复合材料的制备原理和表征方法进行了综述。     

聚氯乙烯/蒙脱土纳米复合材料研究进展

简要介绍了聚氯乙烯/蒙脱土纳米复合材料的有机改性机理和制备方法,重点阐述了聚氯乙烯/蒙脱土纳米复合材料的研究进展。     

表面活性剂和硅烷偶联剂有机复合改性蒙脱土的制备及性能表征

为增加蒙脱土与有机物的相容性,采用十六烷基三甲基溴化铵(CTAB)与硅烷偶联剂(KH-560)对蒙脱土进行了有机复合改性。X-射线衍射和红外光谱的结果表明,CTAB已插入蒙脱土片层,平均层间距离从1.54 nm增大到3.98 nm和2.08 nm,而KH-560未插入蒙脱土片层,只是覆盖在蒙脱土表面,未改变蒙脱土的插层结构;分散性实验表明,表面活性剂和硅烷偶联剂有机复合改性的蒙脱土在苯乙烯、液体石蜡中的分散性好于其他改性蒙脱土;有机复合改性不仅增大了蒙脱土层间距,且改善了蒙脱土与聚氯乙烯的界面效果,提高了蒙脱土在聚氯乙烯基体中的分散均匀性,从而使聚氯乙烯/蒙脱土复合材料玻璃化转变温度的提高和力学性能的改善更明显。     

聚氯乙烯／蒙脱土复合材料的结构与性能研究

采用熔融共混法制备得到PVC／蒙脱土复合材料。通过X射线衍射和透射电镜对复合材料的结构进行了表征。研究了钠基蒙脱土和烷基季铵盐改性的有机蒙脱土对聚氯乙烯／蒙脱土复合材料的结构、加工热稳定性、光学性能、力学性能和结构流变性能的影响。     

聚氯乙烯/蒙脱土纳米复合材料的研究进展Ⅱ性能及应用

本文对插层法制备聚氯乙烯/蒙脱土纳米复合材料的力学性能、热性能、玻璃化转变等方面进行了综述,并对聚氯乙烯/蒙脱土纳米复合材料的应用情况作了简单的介绍,最后指出了在目前研究中存在的一些不足及今后研究的方向.     

AP/HTPB复合推进剂用纳米Co粉的制备

以CoCl_2·H_2O和水合联氨(N_2H_4·H_2O)为主要原料,采用化学还原法制备了纳米Co粉.在不同工艺条件下制备了树枝状纳米Co粉和球形纳米Co粉,用TEM和XRD对产物进行了表征,同时用DTA测试了加入球形纳米Co粉后AP的热分解性能.结果表明,反应介质的黏度和分散剂性质对纳米Co粉粒度及形貌影响较大,在最佳工艺条件下制备了颗粒尺寸均匀、粒度为50~60 nm的球形纳米Co粉;球形纳米Co粉能使AP热分解反应的高温分解峰温度显著下降;添加质量分数2%的球形纳米Co粉,复合推进剂的燃速明显提高,压力指数大幅降低.     

UHMWPE/LLDPE/BN复合塑料导热性能研究

将氮化硼(BN)粒子和超高分子量聚乙烯/线性低密度聚乙烯(UHMWPE/LLDPE)分别用熔融辊炼法和粉末混合法制备导热聚乙烯塑料。研究了制备方式、填料含量及偶联剂对填料分散状态及体系热导率、热阻的影响。研究结果表明,粉末法制备的塑料由于BN的高分散效果使得体系的导热性能明显高于熔融辊炼法制备的体系,热导率随填料含量而增加,偶联剂处理有利于提高塑料的热导率。在UHMWPE/LLDPE/BN中添加少量氧化铝短纤维有助于提高体系的力学强度、韧性及热导率。     

超细滑石粉/聚乳酸复合材料的制备与表征

以偶联剂γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH-560)处理后的超细滑石粉为增强相,聚乳酸(PLA)为基体,制备了超细滑石粉/PLA复合材料。通过傅里叶变换红外光谱(FT-IR)、电子扫描显微镜(SEM)、X射线衍射(XRD)、光学解偏振法、温度-形变曲线及热失重(TG)对复合材料进行了表征。结果表明,KH-560成功地包覆在滑石粉表面,滑石粉表面与PLA基体发生了化学键合,处理后的滑石粉粒子与PLA基体之间形成了良好的界面。适量的滑石粉能够提高PLA基体的结晶速率和结晶度,当滑石粉添加量增大到一定程度,PLA基体的晶格参数和晶体结构会发生变化。当滑石粉分散良好时,复合材料的玻璃化转变温度(Tg)和热稳定性显著提高。     

Reaction Processes and Characterization of ZrB2 Powder Prepared by Boro/Carbothermal Reduction of ZrO2 in Vacuum

The present work was concentrated mainly on the reaction processes of boro/carbothermal reduction (BCTR) of ZrO₂ with B₄C and carbon in vacuum, and characterization of morphology and sinterability of the obtained ZrB₂ powder. Combining the thermodynamic calculations, X-ray diffraction results, and the trend of furnace pressure with temperature during synthesis, a detailed explanation of the reaction processes of BCTR was developed. Most of the ZrB₂ particles obtained at 1650°C presented a nearly spherical morphology, whereas those synthesized at 1750°C showed a nearly columnar morphology with an increased size. Compared with the powder synthesized at 1750°C as well as the commercially additive-free powder used in the reported work, the ZrB₂ powder synthesized at 1650°C showed a better sinterability due to its smaller particle size and lower oxygen content.     

Suspension Processing of Al2O3/SiC Whisker Composites

Homogeneous Al₂O₃ powder/SiC whisker compacts were prepared by suspension processing. By optimizing the conditions for particle/whisker codispersion, castable suspensions could be prepared at total-solids concentrations 50 vol%. Green bodies with high relative density (∼66% to 70%) were obtained with SiC whisker contents in the range of 5 to 30 vol%. Although densification was severely inhibited by the SiC whiskers, significantly higher sintered densities were obtained by suspension processing compared to dry processing.     

Sb-SnO2/BaSO4导电粉末的制备与表征

以重晶石粉为基体,采用化学共沉淀技术制得表面包覆掺锑氧化锡的Sb-SnO2/BaSO4导电粉末.用差热/热重分析前驱体的热处理特性.用X射线衍射表征样品的结构.系统研究水解pH值和温度、SnCl4·5H2O/SbCl3摩尔比、SnCl4·5H2O用量和焙烧制度对导电粉末电阻率的影响规律.产物的电阻率为13Ω·cm、平均粒径为3 4μm,具有广泛的应用前景.探讨了锑掺杂氧化锡的缺陷与能级效应,确定了导电粉末中掺杂效应的缺陷反应.这种方法为矿物基功能材料的低成本制备提供了新的思路.     

B位离子共沉-煅烧法制备Ba(Mg1/3Ta2/3)O3微波陶瓷材料

采用钽镁共沉淀法制备ＭｇＴａ２Ｏ６粉体,然后与ＢａＣＯ粉体混合制备Ｂａ（Ｍｇ１／３Ｔａ２／３）Ｏ３（简称ＢＭＴ）微波陶瓷材料,成功地解决了ＴａＣｌ３溶解问题。对钽镁共沉条件和粉体热分解工艺与粉体的平均粒径和钽镁比例关系;ＢＭＴ陶瓷制备工艺与材料的微观结构和微波性能关系进行了研究,制备的ＭｇＴａ２Ｏ６晶相粉体平均粒径为０．３μｍ,最大与最小粒径比为５。制备的ＢＭＴ陶瓷的几乎不含ＢａＴａ２Ｏ６等杂相,     

羊毛粉/PP共混纺丝和复合纺丝纤维的研究

采用高压空气粉碎羊毛制得的羊毛粉,与聚丙烯(PP)熔融共混纺丝和皮芯型复合纺丝,分别制得羊毛粉/PP共混纤维和复合纤维。对比分析了羊毛粉/PP共混纤维、复合纤维及纯PP纤维的结构和性能。结果表明:羊毛粉/PP共混纤维的断裂强度、初始模量高于复合纤维及纯PP纤维,其大小顺序依次为共混纤维、纯PP纤维、复合纤维;羊毛粉/PP共混纤维的表面染色深度(K/S值)高于复合纤维及PP纤维,其大小顺序依次为共混纤维、复合纤维、纯PP纤维;羊毛粉/PP共混纤维和复合纤维的回潮率均高于纯PP纤维,其大小顺序依次为复合纤维、共混纤维、纯PP纤维。     

Phase Stability of Chemically Derived Enstatite (MgSiO3) Powders

A modified Pechini chemical preparation technique was used to produce enstatite (MgSiO₃) powder. By this method, low-temperature stable orthoenstatite (OE) was obtained at 850°C after 2 h of calcination. The effects of annealing temperature/time, initial particle size, chemical dopants, and shear stress on the conversion of protoenstatite (PE) to clinoenstatite (CE) on the powder have been studied. The results indicated that the transformation of orthorhombic PE to monoclinic CE was sensitive to the initial powder particle size as well as to the type and amount of chemical dopant used. Sodium ions (Na₊), which were found to cause the formation of a glassy phase around the PE grains, destabilized the PE phase physically. In comparison, manganese ions (Mn₂₊), were found to preferentially substitute for the smaller Mg₂₊ ions in solid solution and stabilized the PE phase chemically. The powders with different chemical dopants were examined by TEM and EDS.     

Role of Water Vapor in Crystallite Growth and Tetragonal-Monoclinic Phase Transformation of ZrO2

The role of water vapor in crystallite growth and the tetragonal-to-monoclinic phase transformation of ZrO₂ was studied using three specially prepared samples: an ultrafine powder of monoclinic ZrO₂ obtained by hydrolysis of ZrOCI₂, an aggregated powder of tetragonal ZrO₂ obtained by thermal decomposition of Zr(OH)₄ under reduced pressure, and an ultrafine powder of tetragonal ZrO₂ obtained by thermal decomposition of zirconyl acetate dispersed in caramel. The samples were heat-treated up to 1000°C in dry and wet atmospheres saturated with water vapor at 90°C. It was found that water vapor markedly accelerated crystallite growth for both monoclinic and tetragonal ZrO₂ and facilitated the tetragonal-to-monoclinic phase transformation. Water vapor increases surface diffusion and thus enhances crystallite growth and decreases surface energy, which leads to stabilization of the tetragonal phase.