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小角X-射线散射法解析多结构域蛋白质或复合物的溶液结构 被引量:5
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作者 刘帅 胡红雨 《生命科学》 CSCD 北大核心 2009年第1期15-20,共6页
随着同步辐射装置的建设与发展及各种建模方法的产生与完善,小角X-射线散射(small angleX-ray scattering,SAXS)法已经逐渐成为结构生物学中的一种重要的工具。SAXS可以用于研究溶液中生物大分子的结构及构象变化,蛋白质的组装、折叠等... 随着同步辐射装置的建设与发展及各种建模方法的产生与完善,小角X-射线散射(small angleX-ray scattering,SAXS)法已经逐渐成为结构生物学中的一种重要的工具。SAXS可以用于研究溶液中生物大分子的结构及构象变化,蛋白质的组装、折叠等动态过程。本文对SAXS的基本原理、常用的研究技术和建模方法及其应用进行了综述。 展开更多
关键词 小角x-射线散射 多结构域蛋白质 蛋白质复合物 从头计算 刚体建模
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小角X-射线散射与结构预测法研究中国人乳β-酪蛋白的3级结构 被引量:1
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作者 王辰元 李萌 刘宁 《中国食品学报》 EI CAS CSCD 北大核心 2015年第10期223-229,共7页
通过小角X-射线散射与结构预测的方法研究人乳β-酪蛋白的3级结构,并分析其生理功能。通过使用DEAE Sepharose FAST Flow琼脂糖凝胶获得纯度大于90%的β-酪蛋白纯品,并对其溶液进行小角X-射线散射(0.2 mol磷酸盐缓冲溶液,10 mmol DTT,p ... 通过小角X-射线散射与结构预测的方法研究人乳β-酪蛋白的3级结构,并分析其生理功能。通过使用DEAE Sepharose FAST Flow琼脂糖凝胶获得纯度大于90%的β-酪蛋白纯品,并对其溶液进行小角X-射线散射(0.2 mol磷酸盐缓冲溶液,10 mmol DTT,p H 6.7),将获得的人乳β-酪蛋白的结构信息与通过折叠识别及从头预测构建的预测模型进行比较,筛选出在试验条件下与试验结果最相符的人乳β-酪蛋白3级结构模型,该模型结构松散,含有较少的α-螺旋和β-折叠。同时结合模型对人乳β-酪蛋白磷酸化、糖基化及脂质化等蛋白质功能位点进行了分析,认为人乳β-酪蛋白含有12个可以与乳糖或葡萄糖结合的糖基化位点,7个脂质化位点,其磷酸化位点与已知的5个磷酸化位点相符。 展开更多
关键词 人乳β-酪蛋白 3级结构 小角x-射线散射 结构预测
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三种长链季铵盐在低共熔溶剂中胶束结构的小角X-射线研究
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作者 郁晶丹 陈恩慧 +2 位作者 沈可 刘宇煊 李钦堂 《广州化学》 CAS 2022年第5期62-67,共6页
通过小角X-射线散射技术,研究了十二烷基三甲基溴化铵(DTAB)、十四烷基三甲基溴化铵(TTAB)、十六烷基三甲基溴化铵(CTAB)三种阳离子季铵盐表面活性剂在ChG和ChEG低共熔溶剂中的胶束行为并表征胶束的结构。研究结果表明,表面活性剂烷基... 通过小角X-射线散射技术,研究了十二烷基三甲基溴化铵(DTAB)、十四烷基三甲基溴化铵(TTAB)、十六烷基三甲基溴化铵(CTAB)三种阳离子季铵盐表面活性剂在ChG和ChEG低共熔溶剂中的胶束行为并表征胶束的结构。研究结果表明,表面活性剂烷基链长及低共熔溶剂类型对胶束结构影响较大,而温度对其影响较小。所得结果为低共熔溶剂中有序分子聚集体的构建提供参考。 展开更多
关键词 季铵盐表面活性剂 低共熔溶剂 胶束 疏溶剂作用 小角x-射线散射
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聚己内酯在聚己内酯苯乙烯丙烯腈共聚物共混体系中的受限结晶 被引量:10
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作者 王淑云 蒙延峰 +4 位作者 霍红 李宏飞 蒋世春 安立佳 姜炳政 《高分子学报》 SCIE CAS CSCD 北大核心 2005年第2期203-206,共4页
通过示差扫描量热 (DSC)、广角X 射线衍射 (WAXD)和小角X 射线散射 (SAXS)在不同尺度范围研究了聚己内酯 (PCL) 苯乙烯 丙烯腈共聚物 (SAN)共混体系中PCL的结晶行为 .由于该体系中SAN的玻璃化温度高于PCL的熔点 ,从而导致了PCL的结晶... 通过示差扫描量热 (DSC)、广角X 射线衍射 (WAXD)和小角X 射线散射 (SAXS)在不同尺度范围研究了聚己内酯 (PCL) 苯乙烯 丙烯腈共聚物 (SAN)共混体系中PCL的结晶行为 .由于该体系中SAN的玻璃化温度高于PCL的熔点 ,从而导致了PCL的结晶行为是一种受限结晶 .研究结果表明PCL的结晶行为从宏观 (DSC结果 )、介观 (SAXS结果 )到微观 (WAXD结果 )都受到了高玻璃化温度SAN的限制 . 展开更多
关键词 丙烯腈共聚物 聚己内酯 共混体系 苯乙烯 小角x-射线散射 示差扫描量热 x-射线衍射 结晶行为 高玻璃化温度 PCL 研究结果 SAN 介观
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聚合物 PTMPS 和 PTMPS-DMS 的 SAXS 研究
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作者 金祖铨 周嘉芳 +1 位作者 李思滔 李德芬 《天津大学学报》 EI CAS CSCD 1998年第1期41-44,共4页
用小角X-射线散射(SAXS)法研究了聚四甲基苯撑硅氧烷(PTMPS)和聚四甲基苯撑硅氧烷-二甲基硅氧烷(PTMPS-DMS)多嵌段共聚物超分子结构参数——结晶层厚度a、一维结晶度K和长周期C随DMS含量变化的规律.... 用小角X-射线散射(SAXS)法研究了聚四甲基苯撑硅氧烷(PTMPS)和聚四甲基苯撑硅氧烷-二甲基硅氧烷(PTMPS-DMS)多嵌段共聚物超分子结构参数——结晶层厚度a、一维结晶度K和长周期C随DMS含量变化的规律.发现DMS含量为50%时,关系曲线均呈现一个转折点. 展开更多
关键词 小角x-射线散射 聚合物 TPMPS DMS
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织物在非离子表面活性剂反胶束体系中同浴染色及酶处理
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作者 关晋平 杨如馨 《国外丝绸》 2005年第6期1-3,共3页
主要研究了羊毛织物在非离子表面活性剂反胶束体系中的同浴染色及酶处理。所用表面活性剂为聚氧乙烯山梨醇油酸酯(吐温-85)。酶在吐温-85反胶束体系中的溶解性通过小角X-射线散射分析法测定。测定结果表明,吐温-85反胶束体系可以将染料... 主要研究了羊毛织物在非离子表面活性剂反胶束体系中的同浴染色及酶处理。所用表面活性剂为聚氧乙烯山梨醇油酸酯(吐温-85)。酶在吐温-85反胶束体系中的溶解性通过小角X-射线散射分析法测定。测定结果表明,吐温-85反胶束体系可以将染料和酶同时置于该反胶束体系内部而不会改变染料和酶的结构。在该反胶束体系中,羊毛织物对酸性染料和活性染料可有效吸附。不同的酶在该体系中的反应活性不同,染料对酶有负面作用。 展开更多
关键词 反胶束 蛋白酶 小角x-射线散射 染色 非离子表面活性剂
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EH-型催化剂异相聚合聚乙烯结晶性能研究 Ⅰ.稀溶液结晶
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作者 刘佑习 郭誉文 杨始堃 《中山大学学报论丛》 1990年第3期42-47,共6页
用小角X-射线散射、广角X-射线衍射、差示扫描量热法,研究了EH-型钛系催化剂异相聚合聚乙烯稀溶液结晶的熔点、熔化热、结晶度、长周期、晶区厚度和非晶区厚度随分子量与结晶温度的关系,并着重讨论了不同温度下稀溶液结晶聚乙烯的晶体... 用小角X-射线散射、广角X-射线衍射、差示扫描量热法,研究了EH-型钛系催化剂异相聚合聚乙烯稀溶液结晶的熔点、熔化热、结晶度、长周期、晶区厚度和非晶区厚度随分子量与结晶温度的关系,并着重讨论了不同温度下稀溶液结晶聚乙烯的晶体完整性。 展开更多
关键词 聚乙烯 溶液结晶 小角x-射线散射 广角x-射线衍射 差示扫描量热法
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纤维素纳米纤维增强丝素体系的相界面研究
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作者 陈建 张超 +2 位作者 邵惠丽 胡学超 张耀鹏 《合成技术及应用》 2016年第4期13-16,27,共5页
以丝素蛋白为基体,以细菌纤维素纳米纤维束(BCNRs)为增强体,通过冷冻干燥制备出具有插层结构且力学性能显著增强的复合支架。通过同步辐射原位小角X-射线散射研究了BCNRs丝素蛋白混合溶液在剪切下的相界面结构变化,考察了两相之间的界... 以丝素蛋白为基体,以细菌纤维素纳米纤维束(BCNRs)为增强体,通过冷冻干燥制备出具有插层结构且力学性能显著增强的复合支架。通过同步辐射原位小角X-射线散射研究了BCNRs丝素蛋白混合溶液在剪切下的相界面结构变化,考察了两相之间的界面厚度和均方旋转半径变化过程,并通过软件模拟得到聚集体的三维结构变化,进而从微观角度探究其增强机理。 展开更多
关键词 丝素蛋白 细菌纤维素 纳米纤维 小角x-射线散射 微观结构 相界面
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Porous Structure, Salt Component Distribution and Catalytic Preference of Zinc Acetate Catalysts for Vinylacetate Synthesis on Modified Carbon Supports 被引量:2
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作者 Hoang Kim Bong Oleg Naumovich Temkin +1 位作者 Hoang Huu Binh Dorina Ivanova Yamandiy 《Journal of Chemistry and Chemical Engineering》 2011年第5期473-477,共5页
The main problem in an efficient Zn(CH3COO)2/AC (AC-activated carbon) catalyst preparation is the achievement of uniform distribution of highly dispersed salt component on the activated carbon (AC) surface. The ... The main problem in an efficient Zn(CH3COO)2/AC (AC-activated carbon) catalyst preparation is the achievement of uniform distribution of highly dispersed salt component on the activated carbon (AC) surface. The solution of this problem is modification of the AC by hydrogen peroxide (H202) oxidation of the surface and treatment of AC with acetic acid as well as special methods of salt deposition and catalyst drying. The investigations of these ways of AC surface modification (treatment of AC with acetic acid and H2O2) have demonstrated the obtained AC to have both an increased adsorption capacity as to Zn(OAc)2 and optimum volumes of meso- and micro-pores as well as high catalyst activity in vinyl acetate (VA) synthesis. The characteristics of supports and catalysts were found out by benzene, water and acetic acid vapors adsorption. The distribution of the salt on the AC surface was studied by small-angle X-ray scattering (SAXS), by scanning electron microscopy (SEM) and X-ray micro-analysis (XMA). The catalysts were tested in vinyl acetate synthesis in flow-bed isothermal reactor by cyclic method at 175, 205 and 230℃. 展开更多
关键词 Activated carbon kinetic adsorption porosity nanostructures vinyl acetate synthesis catalysts activity.
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Investigation of Temperature Dependency of Morphological Properties of Thermoplastic Polyurethane using WAXS and SAXS Monitoring 被引量:1
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作者 Steffen Thomas Witzleben Katharina Walbrueck +1 位作者 Stephanie Elisabeth Klein Margit Schulze 《Journal of Chemistry and Chemical Engineering》 2015年第8期494-499,共6页
Polyether and polyether/ester based TPU (thermoplastic polyurethanes) were investigated with wide-angle XRD (X-ray diffraction) and SAXS (small angle X-ray scattering). Furthermore, SAXS measurements were perfor... Polyether and polyether/ester based TPU (thermoplastic polyurethanes) were investigated with wide-angle XRD (X-ray diffraction) and SAXS (small angle X-ray scattering). Furthermore, SAXS measurements were performed in the temperature range of 30 ℃ to 130 ℃. Polyether based polymers exhibit only one broad diffraction signal in a region of 2 θ 15° to 25°. In case of polyurethanes with ether/ester modification, the broad diffraction signal arises with small sharp diffraction signals. SAXS measurements of polymers reveal the size and shape of the crystalline zones of the polymer. Between 30 ℃ and 130 ℃ the size of the crystalline zone changes significantly. The size decreases in most of investigated TPU. In the case of Desmopan 9365D an increase of the particle size was observed. 展开更多
关键词 Thermoplastic polyurethanes MORPHOLOGY mechanical properties SAXS WAXS temperature influence CRYSTALLINITY
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Effect of Different Aromatic Fractions on Colloidal Property of Tahe Atmospheric Residue 被引量:1
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作者 Yu Shuanglin Zhang Jiling +3 位作者 Cheng Tao Rong Lili Xue Peng Shan Honghong 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2012年第3期17-23,共7页
Different amounts of FCC slurry oil and HVGO were added to Tahe atmospheric residue respectively. The colloi- dal stability and asphaltene agglomeration of atmospheric residue and mixed oils were characterized by mean... Different amounts of FCC slurry oil and HVGO were added to Tahe atmospheric residue respectively. The colloi- dal stability and asphaltene agglomeration of atmospheric residue and mixed oils were characterized by means of the mass fraction normalized conductivity and the small-angle X-ray scattering technology (SAXS). The results indicated that the sta- bility of Tahe atmospheric residue decreased with an increasing amount of these oil fractions. It was found that the decline of the colloidal stability was attributed to the component polarity difference between oil fractions and the atmospheric resi- due. Though the aromaticity of FCC slurry oil was higher than that of HVGO, the polarity of aromatics and resins of FCC slurry oil was lower than those of HVGO. So the degree of the colloidal stability was more seriously destroyed by FCC slurry oil. The dispersion of asphaltenes in Tahe atmospheric residue was changed by adding FCC slurry oil and HVGO. The particle size of as-ohaltenes increased alon~ with the decline of the colloidal stability 展开更多
关键词 RESIDUE colloidal stability polarity SAXS particle size
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Adsorption behavior of petroleum asphaltenc Adsorption model
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作者 ZHANG Lei QUE Guo-he DENG Wen-an ZHAO Li-wa 《Journal of Chemistry and Chemical Engineering》 2009年第4期53-58,共6页
Asphaltene is one of the most heavy components, asphaltene adsorption is a serious problem in oil production and processing. In this paper, the progress in the investigation of asphaltene adsorption from the aspects o... Asphaltene is one of the most heavy components, asphaltene adsorption is a serious problem in oil production and processing. In this paper, the progress in the investigation of asphaltene adsorption from the aspects of adsorption model and adsorption behavior is reviewed. Asphaltene of adsorption model include the Langmuir, Freundlich, Langmuir-Freundlich, Rcdlich-Pctcrson, BET adsorption isothcrm. The adsorption behavior of asphaltene was characterized by a variety of structure-probing methods such as N:-adsorption, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS) measurements, and FT-IR spectroscopy. To understand better the adsorption progress of petroleum, asphaltene must understand the whole adsorption behavior of asphaltene. 展开更多
关键词 petroleum asphaltene adsorption model Freundlich model Langmuir model
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Complexation of DNA with cationic surfactants as studied by small-angle X-ray scattering 被引量:1
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作者 NIU Lin YAN JingJing +4 位作者 YANG XuYan BURGER Christian RONG LiXia HSIAO Benjamin LIANG DeHai 《Science China Chemistry》 SCIE EI CAS 2014年第12期1738-1745,共8页
The phase behaviors of the complex formed by didodecyldimethylammonium bromide(DDAB)and cetyltrimethylammonium bromide(CTAB)interacting with three different types of DNAs,salmon testes DNA(~2000 bp),21-bp double... The phase behaviors of the complex formed by didodecyldimethylammonium bromide(DDAB)and cetyltrimethylammonium bromide(CTAB)interacting with three different types of DNAs,salmon testes DNA(~2000 bp),21-bp double-stranded oligonucleotides(oligo-ds DNA),and 21-nt single-stranded oligonucleotides(oligo-ss DNA)were studied by synchrotron small-angle X-ray scattering.It was found that the DNA length and flexibility,together with the positive/negative charge ratio,determined the final structure.At higher charge ratios,the DNA length exhibited negligible effect.Both oligo-ds DNA and salmon DNA formed inverted hexagonal packing of cylinders with CTAB,as well as bilayered lamella with DDAB.However,at lower charge ratios,oligo-ds DNA formed a distorted hexagonal phase with CTAB and a new structure with DDAB,which was different from the behaviors of salmon DNA.The flexible oligo-ss DNA formed rich structures that were subject to environmental disturbance.Kinetic study also indicated that the structures of the complex formed by oligo-ss DNA took much longer to mature than the structures formed by oligo-ds DNA.We attributed this result to the conformational adjustment of oligo-ss DNA in the complex. 展开更多
关键词 phase behavior DNA SURFACTANT synchrotron small-angle x-ray scattering kinetics
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Brij35/油酸钠/油酸/水体系的溶致液晶性质——应用偏光显微镜,SAXS,~2H-NMR和流变等方法 被引量:13
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作者 安娅 徐军 +6 位作者 张晋 胡长刚 李干佐 王志宁 王仲妮 张笑一 郑利强 《中国科学(B辑)》 CSCD 北大核心 2006年第3期234-243,共10页
首先研究Brij35(十二烷基聚氧乙烯(23)醚)/油酸钠/油酸/水体系的拟三元相图,发现该体系最大的特点是溶致液晶占相图总面积的2/3.对O/W型微乳液进行流动曲线研究,属于牛顿流体.对溶致液晶体系开展了偏光显微镜,SAXS,2H-NMR等方法... 首先研究Brij35(十二烷基聚氧乙烯(23)醚)/油酸钠/油酸/水体系的拟三元相图,发现该体系最大的特点是溶致液晶占相图总面积的2/3.对O/W型微乳液进行流动曲线研究,属于牛顿流体.对溶致液晶体系开展了偏光显微镜,SAXS,2H-NMR等方法的研究.当体系组成沿着相图中AA′线改变时,其液晶结构变化的顺序是,立方状液晶→立方状与层状液晶共存→层状液晶→层状液晶与六角状液晶共存→六角状液晶.并且对上述体系系统地开展了流变性质的研究.其结果再一次证实液晶结构随着体系中某组分的改变而发生变化.同时还得到立方液晶和六角状液晶的晶格参数,分别为10.53和5.68 nm. 展开更多
关键词 Brij35 溶致液晶 2H-NMR偏光纹理 小角x-射线散射(SAXS) 流变性质
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N-甲基-N-十六烷基溴化物在水中的自组装行为研究(英文)
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作者 李翠华 钱练安 +3 位作者 何晋华 刘剑洪 张黔玲 罗仲宽 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2012年第S3期48-51,共4页
设计合成了非芳香类杂环离子液体N-甲基-N-十六烷基溴化物,并研究该离子液体在水中的自组装行为和液晶结构。该离子液体/水二元体系表现出双向溶致型六角相液晶,液晶范围和外观与离子液体浓度、温度相关。随着浓度增加,离子液体/水二元... 设计合成了非芳香类杂环离子液体N-甲基-N-十六烷基溴化物,并研究该离子液体在水中的自组装行为和液晶结构。该离子液体/水二元体系表现出双向溶致型六角相液晶,液晶范围和外观与离子液体浓度、温度相关。随着浓度增加,离子液体/水二元体系外观由澄清溶液变为透明溶胶,最后变为白色凝胶。溶致液晶在离子液体浓度范围30%~60%、升温过程中温度范围0.5~9.2℃、降温过程中4.8~19.8℃形成。与咪唑类离子液体在水中形成的液晶相比,饱和杂环离子液体分子由于缺少芳香环重叠效应,端头基重叠作用力减弱,使得饱和杂环离子液体分子在水中以较松散的方式组装。 展开更多
关键词 N-甲基-N-十六烷基溴化物 溶致液晶 自组装 小角x-射线散射
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Pore structure of selected Chinese coals with heating and pressurization treatments 被引量:7
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作者 CAI YiDong LIU DaMeng +3 位作者 PAN ZheJun YAO YanBin LI JunQian QIU YongKai 《Science China Earth Sciences》 SCIE EI CAS 2014年第7期1567-1582,共16页
Pore structure of Chinese coals with heating and pressurization treatments was studied using small angle X-ray scattering (SAXS), N2 adsorption/desorption isotherms and scanning electron microscope (SEM). SAXS was... Pore structure of Chinese coals with heating and pressurization treatments was studied using small angle X-ray scattering (SAXS), N2 adsorption/desorption isotherms and scanning electron microscope (SEM). SAXS was performed for some sam- ples after heat treatment at seven elevated temperatures from 25 to 250℃ at 0 MPa and for other samples with hydrostatic pressure treatment at 0, 5, 10, 15 and 20 MPa at the room temperature. The results show that N2 adsorption isotherm together with SAXS could be a comprehensive method to evaluate the pore shape and the pore size distribution: the pore shapes are generally spherical for low rank coal and they are mainly ellipsoidal for high rank coal. All these measurements were then interpreted using the fractal theory to reveal relationship between surface fractals and coal rank, and the evolution of surface fractals under heating and pressurization treatments. The results show that surface fractal dimension (Ds) changes with different treating temperature and pressure and maximum vitrinite reflectance (Ro,m). Especially in the bituminous stage, Ds shows an increasing trend with Ro,m under varied temperatures. Moreover, Ds shows an increasing trend with increasing temperature before 200℃, and a decreasing trend after 200℃. Furthermore, the results show that Ds has a more complex relationship with Ro.m under varied treating temperature than that under varied treating pressure. 展开更多
关键词 SAXS pore structure COALS heating and pressurization treatment surface fractal
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Densely quaternized anion exchange membranes synthesized from Ullmann coupling extension of ionic segments for vanadium redox flow batteries 被引量:8
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作者 Yu Chen Qilang Lin +2 位作者 Yuying Zheng Yan Yu Dongyang Chen 《Science China Materials》 SCIE EI CSCD 2019年第2期211-224,共14页
Membranes with high ion conductivity and selectivity are important for vanadium redox flow batteries.Herein, densely quaternized anion exchange membranes based on quaternary ammonium functionalized octa-benzylmethyl-c... Membranes with high ion conductivity and selectivity are important for vanadium redox flow batteries.Herein, densely quaternized anion exchange membranes based on quaternary ammonium functionalized octa-benzylmethyl-containing poly(fluorenyl ether ketone)s(QA-OMPFEKs) were prepared from the(i) condensation polymerization of a newly developed octa-benzylmethyl-containing bisphenol monomer via Ullmann coupling,(ii) bromination at the benzylmethyl sites using N-bromosuccinimide, and(iii)quaternization of the bromomethyl groups using trimethylamine. The QA-OMPFEK-20 with an ion exchange capacity(IEC) of 1.66 mmolg^-1 exhibited a higher SO42-conductivity(9.62mScm^-1) than that of the QA-TMPFEK-40(4.82mScm^-1) at room temperature, which had a slightly higher IEC of 1.73 mmolg-1but much lower QA density.The enhanced SO42-conductivity of QA-OMPFEK-20 was attributed to the ion-segregated structure arising from the densely anchored QA groups, which was validated by SAXS observation. Furthermore, the QA-OMPFEK-20 showed much lower VO2+permeability(1.24×10^-14m^2s^-1) than QA-TMPFEK-40(5.40×10^-13m^2s^-1) and Nafion N212(5.36×10^-12m^2s^-1), leading to improved Coulombic and energy efficiencies in Vanadium redox flow batteries(VRFBs). Therefore, the Ullmann coupling extension is a valuable approach for the development of high performance anion exchange membranes for VRFBs. 展开更多
关键词 anion exchange membranes quaternary ammonium poly(fluorenyl ether ketone)s Ullmann coupling extension phase separation
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The thermodynamic properties of flow-induced precursor of polyethylene
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作者 Dong Liu Kunpeng Cui +2 位作者 Ningdong Huang Zhen Wang Liangbin Li 《Science China Chemistry》 SCIE EI CAS CSCD 2015年第10期1570-1578,共9页
Flow-induced preordering or precursor(FIP) has been studied in a series of lightly cross-linked high-density polyethylene with a combination of extensional rheology and in situ synchrotron radiation small-angle X-ray ... Flow-induced preordering or precursor(FIP) has been studied in a series of lightly cross-linked high-density polyethylene with a combination of extensional rheology and in situ synchrotron radiation small-angle X-ray scattering(SAXS) and wide-angle X-ray diffraction(WAXD) measurements. Based on the incipient strains of SAXS and WAXD signals during extension in a large temperature range, strain-temperature diagrams for flow-induced preordering and nucleation were constructed and revealed that flow-induced crystallization(FIC) undergoes two stages: melt-precursor transition(MPT) and precursor-nuclei transition(PNT). At different temperatures, FIP with different inner structures and morphologies can be induced by strain; these embryos have shape and structure that are related to those of the corresponding critical nuclei. With the strain-temperature diagrams, the thermodynamic properties of FIP are deduced, which shows that compared with the relative nuclei the FIP always has a lower bulk free energy(?H) and a much lower surface free energy(?e). In extreme cases(high temperature), the ?e of FIP can be negligible. The quantitative estimation of the thermodynamic parameters suggests the existence of variant FIPs, which plays a vital role for the subsequent progress of PNT and the whole process of FIC. 展开更多
关键词 flow-induced precursor(FIP) SHISH-KEBAB thermodynamic parameters SAXS WAXD POLYETHYLENE
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