Reinforced properties of polybenzoxazine-based nanocomposites with siloxane benzoxazine-modified halloysite nanotubes

Siloxane benzoxazine monomer (Ba-s) was synthesized using phenol, 3-aminopropyltriethoxysilane (KH-550), and paraformaldehyde, and then introduced onto halloysite nanotubes (HNTs) surface as a coupling agent to obtain functionalized HNTs (mHNTs). 1, 6-hexanediamine/phenol benzoxazine (Ba-h) was selected as a matrix to blend with mHNTs at the mass ratios of 1:0, 9:1, 7:1, 6:1, 4:1,7:3, and 3:2, respectively. The ring-opening copolymerization behaviors of the nanocomposites were investigated by differential scanning calorimetry. The results implied that the polymerization temperature of Ba-h was decreased by the grafted HNTs. The results of thermogravimetric analysis and dynamic mechanical analysis displayed that the obtained copolymers exhibit different degrees of improvement in the thermal stability and mechanical properties of Ba-h. These enhancements are attributed to the homogeneous dispersion of HNTs and the strong matrix-nanoparticle interactions based on SEM and TEM results. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47882.     

低熔点共聚酯的研究进展

介绍了国内外对低熔点共聚酯的研究现状,着重论述了低熔点共聚酯的熔融结晶行为、流变性、热稳定性以及其纺丝工艺研究,并对其发展前景进行了展望。     

一种新型镍-顺丁烯二酸混配配合物的制备与性质研究

在室温下,顺丁烯二酸(mal)、2,2′-联吡啶(bipy)和硝酸镍反应得到一个未见报道的顺丁烯二酸过渡金属混配配合物:[Ni(bipy)(H<,2>O)<,3>(mal)]?H<,2>O,并培养得到其晶体.用元素分析和红外光谱进行了表征,单晶X-射线衍射技术测定了的晶体结构;热分析方法研究了配合物的热稳定性.     

液态氟橡胶改性端羟基嵌段共聚醚粘合剂及其对铝粉热氧化行为的影响

利用氟化物促进铝粉的燃烧是近年来含能材料领域的热点.选用含氟量较高的端羟基液态氟橡胶作为氟源,将其引入端羟基嵌段共聚醚(HTPE)粘合剂体系中,制备不同氟橡胶含量的改性HTPE胶片,并对改性胶片的微观形貌、力学特性、热稳定性和氧化能力进行测试分析.结果表明:随着液态氟橡胶含量的增加,胶片的力学性能先降低后增加,当氟橡胶...     

花椒总生物碱抑菌作用

采用滤纸片法和试管二倍稀释法测定花椒总生物碱的抑菌活性。结果表明花椒总生物碱具有较宽的抗菌谱,花椒总生物碱对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、黑曲霉和酿酒酵母的最小抑菌浓度分别为3．91mg／mL,3．91mg／mL、7．81mg／mL、15．63mg／mL和31．25mg／mL。热稳定性实验表明花椒总生物碱的抑菌活性基本不受温度的影响。     

碱式硫酸镁晶须/橡胶复合材料的制备

将超声分散后的硅烷偶联剂3-氨丙基三乙氧基硅烷改性碱式硫酸镁晶须（KH550-MgOS_W）分散液加入天然胶乳（NR）中,对其进行补强,制得绿色环保高性能的KH550-MgOS_W/NR复合材料。系统研究了KH550-MgOS_W/NR复合材料的力学性能、阻燃性能及热稳定性能。结果表明,用KH550改性后的MgOS_W与橡胶基体具有很好的相容性。KH550-MgOS_W/NR复合材料的力学性能、阻燃性能及热稳定性能均比纯胶有所提高。当KH550-MgOS_W与NR质量比为4%时,KH550-MgOS_W/NR复合材料的各项性能均达到最佳,300%定伸应力、拉伸强度、撕裂强度、断裂伸长率、交联密度比纯胶胶膜分别提高了25.0%、36.8%、37.3%、11.4%、44.2%,垂直燃烧等级由FV-1提高到了FV-0级,比纯胶的起始热降解温度（T₀）、最大热降解温度（T_p）和终止热降解温度（T_f）分别提高了6.2℃、5.2℃和4.1℃。     

层状HNbWO_6粉体的结构特征及热稳定性研究

采用固相反应法合成前驱体α-LiNbWO6,质子交换后得到HNbWO6粉体,利用粉末X射线衍射、扫描电子显微镜、透射电子显微镜、热重分析及拉曼光谱对HNbWO6的结构、形貌及热稳定性进行研究。结果表明,制备的HNbWO6颗粒具有典型层状结构,层间H+以不同水合形式存在,并与层板骨架有着明显的相互作用;随着热处理温度的升高,层间水分子及层板羟基相继脱除,HNbWO6的特征衍射峰及骨架振动发生明显且有规律的变化。     

炼镁还原罐用钢的耐热机理分析

文章对在1200℃～500℃工作条件下奥氏体耐热钢中σ相产生的原因及防止σ产生的措施进行了相关的金属学分析。σ相是导致炼镁还原罐早中期破坏的主要原因,针对还原罐用钢的使用条件,通过合金化设计,提高材质的热强性、热稳定性及防止有害相的产生,有望大幅度提高炼镁还原罐的使用寿命。     

碳酸羟基磷灰石粉体的热处理研究

以沉淀法制备了碳酸根质量分数为8.5%的碳酸羟基磷灰石(carbonated hydroxyapatite, CHA),研究热处理工艺参数对其热稳定性和碳酸根替代的影响.通过XRD、FTIR和C/S碳硫仪等测试手段表征了CHA粉体的特性.结果表明,随热处理温度的升高,碳酸根的含量减少,而碳酸根的A型替代与B型替代之比则呈现先降后升的趋势.与湿N2气氛相比,湿CO2气氛能减少碳酸根的损失,提高热稳定性.与干CO2气氛相比,湿CO2气氛有利于生成以B型替代为主的CHA.热处理过程中CO2分压越高,碳酸根的损失量越少,热稳定性越好.     

Formation and Thermal Stability of Large Precipitates and Oxides in Titanium and Niobium Microalloyed Steel

As-cast CC slabs of microalloyed steels are prone to surface and sub-surface cracking. Precipitation phenomena initiated during solidification reduce ductility at high temperature. The unidirectional solidification unit is employed to simulate the solidification process during continuous casting. Precipitation behavior and thermal stability are systematically investigated. Samples of adding titanium and niobium to steels have been examined using field emission scanning electron microscope （FE-SEM）, electron probe X-ray microanalyzer （EPMA）, and transmission electron microscope （TEM）. It has been found that the addition of titanium and niobium to high-strength low-alloyed （HSLA） steel resulted in undesirable large precipitation in the steels, i. e. , precipitation of large precipitates with various morphologies. The composition of the large precipitates has been determined, The effect of cooling rate on （Ti, Nb）（C, N） precipitate formation is investigated. With increasing the cooling rate, titanium-rich （Ti,Nb）（C,N） precipitates are transformed to niobium-rich （Ti,Nb）（C,N） precipitates. The thermal stability of these large precipitates and oxides have been assessed by carrying out various heat treatments such as holding and quenching from temperature at 800 and 1 200℃. It has been found that titanium-rich （Ti,Nb）（C,N） precipitate is stable at about 1 200 ℃ and niobium-rich （Ti,Nb）（C,N） precipitate is stable at about 800 ℃. After reheating at 1 200℃ for 1 h, （Ca,Mn）S and TiN are precipitated from Ca-Al oxide. However, during reheating at 800 ℃ for l h, Ca-Al-Ti oxide in specimens was stable. The thermodynamic calculation of simulating the thermal process is employed. The calculation results are in good agreement with the experimental results.