WU Tao
,
WANG Ming-zhi
,
GAO Yu-wei
,
LI Xiao-pu
,
ZHAO Yu-cheng
,
ZOU Qin
钢铁研究学报(英文版)
The warm compression tests were performed on the eutectoid steel to investigate the evolution of cementite morphology. Several processing parameters, such as temperature, strain rate and reduction, were changed to analyze the effect of each parameter on spheroidization of cementite. The results showed that the warm compression promoted the fragmentize and the spheroidization of lamellar cementites. When the specimen was compressed with reduction of 50% at 700 ℃ and in the strain rate of 0.01 s-1, the excellent spheroidized cementite was obtained. The mechanism of fragmentation and spheroidization of lamellar cementites during compression was discussed by using transmission electron microscope. The formation of spheroidized cementite was related to the time of compression process. The fragmentize of lamellar cementites was due to the extension of sub-grain boundary in the cementite. The spheroidization of cementite depended on the diffusion of carbon atoms at the tip of bended and breakup cementite.
关键词:
eutectoid steel
,
warm compression
,
lamellar cementite
,
fragmentize
,
cementite spheroidization
于静
,
司高华
,
黄云贵
,
刘东旭
应用化学
doi:10.3724/SP.J.1095.2011.00388
Pu(Ⅲ)、Pu(Ⅳ)、Pu(Ⅴ)和Pu(Ⅵ)在自然水的pH和Eh(氧化还原电势)值范围内能够共存.在自然环境中主要以Pu(Ⅴ)的PuO2(H2O)n+和Pu(Ⅳ)的Pu(OH)4形式存在.采用静态法测定了Pu(Ⅳ)和Pu(Ⅴ)在砂土介质中的分配系数Kd,Pu(Ⅳ)和Pu(Ⅴ)在砂土中的分配系数范围分别为5.5×103～4×104mL/g和3.2×103～1.1×104mL/g.表明在砂土介质中Pu(Ⅳ)的分配系数(Kd)大于Pu(Ⅴ)的,并且分配系数随砂土介质中粘土矿物含量的增加及介质颗粒粒径减小而增大.
关键词:
Pu(Ⅳ)
,
Pu(Ⅴ)
,
砂土
,
分配系数
周向东
,
刘朋生
高分子材料科学与工程
聚氨酯(PU)在氮气保护下经60Co-γ射线照射后表面产生自由基,然后浸入到甲基丙烯酸-β-羟乙酯(HEMA)溶液中接枝,再使PU和HEMA的接枝共聚物(PU-g-PHEMA)在催化剂作用下接枝抗静电剂TN,由此合成表面具有耐久性抗静电的聚氨酯(PU-g-PHEMA-g-TN).通过FT-IR、ESCA、SEM等手段表征了PU辐射接枝HEMA的产物,并研究了影响PU接枝HEMA的主要因素.结果表明,HEMA的接枝率随辐射剂量和单体浓度的增加而增加,随剂量率的增加而减小,低浓度的溶剂(乙醇)有利于接枝.
关键词:
γ-射线
,
聚氨酯
,
接枝
,
甲基丙烯酸-β-羟乙酯
秦东奇
,
王静媛
,
于小强
,
李峰
,
汤心颐
高分子材料科学与工程
采用全自动扭辫仪和驻波管对PU/PMMA IPN 体系的阻尼行为进行了研究.TBA结果表明,填料的最佳填加量为10%.吸音系数测试表明,常温时该种结构的IPN材料的吸音系数与频率近似成峰形,最大吸收在3000 Hz左右.最好的吸音材料的吸音系数峰值为50%以上.
关键词:
阻尼因子
,
吸音系数
,
填料
,
阻尼行为
Dongyan TANG
,
Liangsheng QIANG
,
Zheng JIN
,
Liancheng ZHAO
材料科学技术（英）
Interpenetrating polymer networks (IPNs) composed of acrylate-modified polyurethane (PU)/unsaturated polyester (UP) resin $via$ simultaneous polymerization with various component ratios of PU/UP were prepared. The polymerization processes of IPNs were traced through infrared spectrum (IR) techniques, by which the phase separation in systems could be controlled effectively. Results for the morphology and miscibility among multiple phases of IPNs, obtained by transmission electron microscope (TEM) indicated that the domains between two phases were constricted in nanometer scales. The dynamic mechanical thermal analyzer (DMTA) detection results revealed that the loss factor (tanδ) and loss modulus (E'') increased with the polyurethane amounts in system, and the peak value in curves of tanδ and E'' appeared toward low temperature ranges. Maximum tanδ values of all samples were above 0.3 in the nearly 50℃ ranges. Also, the mechanical properties of PU/UP IPNs were studied in detail.
关键词:
Interpenetrating polymer networks (IPNs)
,
null
,
null
,
null
胡晓宇
,
肖长发
,
安树林
,
王照旭
膜科学与技术
doi:10.3969/j.issn.1007-8924.2007.06.022
采用熔体纺丝后拉伸的方法制备了聚氨酯(PU)/聚偏氟乙烯(PVDF)共混中空纤维膜,研究了拉伸对共混膜形态结构的影响,通过测定水通量随透膜压力的变化讨论了PU/PVDF共混中空纤维膜的压力响应性能,并对不同拉伸倍数所得膜压力响应性能差异进行了研究.结果表明,拉伸过程增大了聚合物间界面微孔的通透性,有效地提高了膜的水通量;且随拉伸倍数的提高,PU/PVDF共混中空纤维膜界面微孔的回复性有所提高.
关键词:
共混中空纤维膜
,
聚氨酯
,
聚偏氟乙烯
,
压力响应
程爱民
,
吴石山
,
沈健
高分子材料科学与工程
制备了不同硬段含量的聚氨酯(PU)及其PU/有机蒙脱土(OMMT)纳米复合材料.研究结果表明,随着PU分子链中硬段含量的增加,PU分子链的刚性提高,进入硅酸盐片层间的位阻增大,使插层变得困难,从而导致进入该硅酸盐片层间的PU分子链减少.OMMT对PU有增强增韧作用,但随着PU分子链中的硬段含量增加,OMMT的增强效果下降.PU及其PU/OMMT纳米复合材料的热稳定性均随着PU分子链中的硬段含量增加而下降.
关键词:
聚氨酯
,
硬段含量
,
蒙脱土
,
纳米复合材料
秦川丽
,
蔡俊
,
唐冬雁
,
张巨生
,
蔡伟民
材料工程
doi:10.3969/j.issn.1001-4381.2003.07.010
采用DMA法研究了热力学、动力学因素及组成比对聚氨酯/乙烯基酯树脂互穿聚合物网络(PU/VER IPN)材料阻尼性能的影响.研究发现:引入丙烯酸酯类单体为VER共聚单体,改善了常规以苯乙烯(St)为共聚单体的PU/VER(St)IPN材料的阻尼性能,含较长酯基的体系具有更优的阻尼性能;通过调整两网络的相对聚合速率及组成比,可使材料出现宽温域阻尼,合成的组成比为80/20、70/30及60/40的IPN材料,在至少近80℃的温域,阻尼因子(tanδ)>0.3.进一步通过TEM检测分析了IPN材料微观结构与阻尼性能的关系.
关键词:
聚氨酯
,
乙烯基酯树脂
,
互穿聚合物网络
,
阻尼材料
李如松
,
何彬
,
张全虎
稀有金属材料与工程
为了对δ相Ga稳定Pu合金中自辐射效应进行分子动力学仿真,本文根据原子分子反应静力学原理.将Pu,Ga和He原子的7Fg(9Fg),2Pu(4Pu]和1Sg(3Sg)分别分解为Pu2(D∞h),PuGa(C∞v),Ga2(D∞h),PuHe(C∞v),GaHe(C∞v),He2(D∞h)的直和,通过直积和约化获得所有可能的电子状态.在Pu原子的相对论有效原子实势(RECP),Ga原子和He原子的6-31IG*全电子基组下,采用Becke-杂化泛函(B3LYP)对Pu-Pu,Pu--Ga,Pu-He,Ga-Ga,Ga-He和He-He势能进行从头算.获得了相应分子的原子间作用势,以及各个分子基态的电子状态.
关键词:
从头
,
原子间作用势
,
多重度
,
泛函
