PET薄膜非晶区结构的RDF研究

本文将在低角度范围应用的X射线衍射计算机分峰法扩展到含所有非晶峰的广角度范围,用分离的广角度非晶散射导出径向分布函数(RDF);并通过对取向产生的附加分布函数分析,研究了成膜过程聚对苯二甲酸乙二醇脂(PET)膜非晶区结构的变化。     

二维红外光谱法分析聚酰胺-66晶区/非晶区结构

应用变温红外光谱法和二维红外光谱法对聚酰胺-66在303～393K范围内的晶区和非晶区结构及热稳定性进行研究。变温一维红外光谱和变温二阶导数红外光谱的试验结果表明,聚酰胺-66的晶区结构对温度变化较为敏感,而非晶区结构相对稳定。非晶区结构的热稳定性在二维红外光谱试验中得到进一步的证实。从聚酰胺-66的分子结构观察,随着温度的升高,其晶区结构(主要对应O=C-NH-)最先改变,而非晶区结构(主要对应-C-C-)则较为稳定。非晶区的异步二维红外光谱试验结果表明,其晶区结构的吸收波数为1 141cm-1(νamorphous-1)和1 138cm-1(νamorphous-2);而非晶区结构的吸收波数为939cm-1(νcrystal-1)和931cm-1(νcrystal-2)。对聚酰胺-66的非晶区结构和晶区结构还同时进行同步二维红外光谱试验,结果表明:随着温度的升高,两者的红外吸收峰的变化快慢顺序为931cm-1(νcrystal-2)1 141cm-1(νamorphous-1)939cm-1(νcrystal-1)1 138cm-1(νamorphous-2)。     

双轴拉伸PET薄膜成膜过程非晶区分子取向的WAXS研究

本文将常应用于小的角度范围(29_(CuK_α)<50°)的结晶峰和非晶峰的计算机分峰法,推广到PET薄膜的广角度散射范围(2θ_(CuK_α)=5°—140°)。通过对分离出来的表征非晶区分子链间分布的非晶主峰特征参数的分析,探讨了在特定拉伸条件下非晶区分子取向在成膜过程的变化。     

南桐煤镜质组非晶结构的X射线衍射研究

本文对经典煤核结构模型评述后，提出了多元非晶煤结构概念。用Ｘ射线衍射方法研究了南桐煤镜质组的原子径各分布，论证了煤大分子中同时存在芳香结构单元和脂环结构单元，它们对Ｘ射线射射强度均有贡献，非晶煤结构的有序性不在于１ｎｍ。     

等规聚苯乙烯结构与性能研究进展

本文综述了等规聚苯乙烯的结构与性能的研究。着重讨论等规聚苯乙烯的差向立体异构化、结晶行为、凝胶特性及其机械力学性能与结构的关系，同时还讨论了等规聚苯乙烯的加工与应用前景。     

乙烯-丙烯酸共聚物非晶区结构和分子运动的固体核磁共振研究

利用固体高分辨1 3CCP MAS和变温固体质子宽线技术对乙烯 丙烯酸共聚物 (EAA)非晶区的结构和分子运动进行了研究 ,结果发现 ,非晶区中羧基之间可以形成氢键 ,其数量随着共聚物中丙烯酸共聚单体含量的增加而增加 ,使得共聚物中非晶区分子运动能力随非晶区相对含量的增加而减弱 ,这是一种与一般的乙烯共聚物相反的变化趋势 .通过交叉极化方法间接测量了非晶区中乙烯链段的1 H自旋 自旋弛豫时间 (T2 ) ,表明非晶区中乙烯链段的运动同样受到氢键的束缚 .随着温度的升高 ,羧基之间的氢键发生解离 ,非晶区的柔性增强     

用θ—2θ型粉末省射仪精确测定溶液结构的新尝试

发展了用θ－２θ型衍射仪测定电解质水溶液结构的新方法,设计了具有恒温功能的超厚液体样品池并建议池窗口强度的校正规程,获得了令人非常满意的实验结果,θ－２θ型粉末衍射仪测定的径向分布函数与θ－θ型衍射仪的自由表面散射比较,表明径向分布函数分辨率有所提高。     

RDF法对非晶态聚醚砜共聚物的近程有序结构研究

用径向分布函数(RDF)研究了聚醚砜共聚物(PES)在r=1.5 nm范围内的近程结构, 结果表明, 分子链间存在近程有序结构, 有序周期约为0.5 nm; 聚醚砜共聚物经退火处理后, 由g(r)图可以看出, 第一个峰变高、变窄; 由G(r)图可以看出, 分子链间第一个有序区内, 分子链间贡献大于链内贡献; 于200 ℃退火处理后有序畴尺寸(rs)略有增大, 原子平均位移(σ)变小, 使得分子链内原子间距分布更加均匀, 相邻分子链间距(rv)变小. 同时透射电镜(TEM)的形态结构分析表明, 经退火处理后, 其聚集态确实形成了某种局部有序的结构.     

离聚体的结构表征——Ⅳ.径向分布函数法测定含氟锌离聚体的微观结构

本文报道用径向分布函数法对含氟的锌离聚体微现结构进行分析。从所测得的干涉函数、双体相关函数及径向分布函数等结构参量可知,锌离聚体的离子微区是由四配位锌氧四面体结构单元构成,配位数为4,Zn~(2+)-O键长2.24A,离子微区尺寸约为10.47A,其可能结构模式如图6所示。     

大孔交联聚苯乙烯的分形结构研究

采用小角Ｘ－射线散法测定大孔交联聚苯乙烯树脂的结构,发现大多数大孔交联聚苯乙烯在数纳米至数十纳米的标度尺寸范围内具有分形结构,分形维数介于２和３之间。本研究还进一步探讨了交联度、致孔剂,功能基化反应及后处理对大孔交联聚苯乙烯分形结构的影响。     

Short range order of amorphous polymers derived by WAXS

Summary Radial difference distribution functions were calculated for PC anda-PS in a temperature range from 293 K to 455 K using wide angle X-ray scattering. Corrections of experimental scattering curves were examined. An assignment for some distances to intra- and intermolecular correlations was made. Next neighbour distances obtained from RDDFs are in good agreement with theoretically computed distances.

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Zusammenfassung Radiale Dichtedifferenzfunktionen für PC anda-PS werden im Temperaturbereich zwischen 393 K und 563 K aus Röntgenweitwinkel-Messungen berechnet. Die erforderlichen Korrekturen der experimentellen Intensitätsverteilung werden sorgfältig überprüft. Für einige Abstände kann eine erste Zuordnung ihres inter- und intramolekularen Ursprungs gegeben werden. Die Abstandswerte für die nächsten Nachbarn aus der RDDF stimmen mit den theoretisch berechneten Werten sehr gut überein.

     

嵌入Y型分子筛中钯簇合成与结构的研究

Pd clusters encaged in Y-zeolite (Pd0Y) have been prepared by means of exchanging zeolite HY with [Pd(NH3)4]2+ under microwave radiation. The product formed was deaminized by heating, washed sufficiently with de-ionized water and reduced with hydrogen. The crystal phase diffraction of Pd was not found in the XRD spectrogram of Pd0y. According to polycrystal X-ray diffraction data. Radial Electron Distribution Function (REDF) of Pd0Y was calculated to elucidate the structure of Pd cluster. The results show that the Pd clusters are of the Al type closely packed arrangement. The dimension of them is about 12 Å. They are encaged in the supercage of zeolite Y. Their occupancy on the supercage is as small as 0.06 so that the framework structure of zeolite Y is unchanged. Therefore, the high dispersing Pd cluster aggregating in supercage exhibit strong catalytic effect. The CO-conversion of Pd0Y with Pd 0.72% and 6.13% (in mass fraction) is 67 % and 100 % (in volume fraction) respectively. Evaluation conditions:
mixed gas containing 0.02% CO and air,
space velocity 3000 h-1,
reaction temperature 0 ℃.     

高斯多峰拟合在径向分布函数中的应用

利用同步辐射X射线散射法测定了盐水摩尔比分别为1:30和1:14的Rb2SO4和Cs2SO4的水溶液结构. 通过对散射数据的处理, 获得了两种溶液的径向分布函数. 采用多峰拟合中的Gaussian法对径向分布函数中金属离子第一水合层附近的叠加峰进行了处理, 多峰拟合结果与实验结果吻合得很好. 通过将拟合数据与已报道的溶液结构和晶体结构对比分析, 确定了每个拟合峰的归属.多峰拟合结果分析表明, Rb+和Cs+第一水合层配位数为6, 为变形的八面体构型. 两种溶液中都存在着金属离子和硫酸根离子接触离子对: Rb—S 和Cs—S 的特征距离分别为0.407和0.427 nm. 研究证实, 多峰拟合有助于阐述溶液中离子的水合结构.     

Sorption of n‐hexane in amorphous polystyrene

Sorption properties of pure n‐hexane vapor in amorphous polystyrene (PS) were studied at 298 K by thermogravimetry under controlled vapor pressure. Two sorption–desorption cycles were performed by varying the relative pressure between 0 and 0.91. Mixing of PS with n‐hexane resulted in a strong plasticization, which was evidenced by quite significant depression in the glass transition temperature of the polymer as shown by differential scanning calorimetry. Maximum quantity of n‐hexane sorbed in the PS at 298 K and at a pressure close to saturation was about 12.4 wt %. The thermogravimetry yielded an isotherm with a strong hysteresis loop, explanation of which was hypothesized with the help of (a) Flory–Huggins sorption model extended by Vrentas, (b) analysis in terms of modification in the glass transition temperature of the n‐hexane/PS system as a function of sorbed quantity, and (c) change in total volume of the system. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1252–1258     

Development of the crystallinity and rigid amorphous fraction in cold‐crystallized isotactic polystyrene

The phase structure of crystalline isotactic polystyrene (iPS) has been investigated with temperature‐modulated differential scanning calorimetry (TMDSC), wide‐angle X‐ray scattering (WAXS), and Fourier transform infrared (FTIR) spectroscopy. Quenched amorphous samples have been cold‐crystallized at 140 or 170 °C for various crystallization times. The degree of crystallinity obtained from WAXS, with the ratio of the crystal peak intensity to the total peak intensity, shows excellent agreement with the crystallinity determined from TMDSC total heat flow endotherms. For the first time, FTIR results show that the absorbance peak ratio (I/I) has a linear correlation with the crystalline mass fraction (χ_c) for cold‐crystallized iPS according to the following relation: I/I = 0.54χ_c + 0.16. This relationship allows the crystallinity of iPS to be determined from infrared spectroscopy analyses in cases in which it is difficult to perform thermal or X‐ray measurements. On the basis of the measurements of the heat capacity increment at the glass transition, we find that a significant amount of the rigid amorphous fraction (RAF) coexists with the crystalline and mobile amorphous phases in cold‐crystallized iPS. The RAF increases systematically with the crystallization time, and a greater amount is formed at a lower crystallization temperature. A three‐phase model (crystalline phase, mobile amorphous phase, and rigid amorphous phase) is, therefore, appropriate for the interpretation of the structure of cold‐crystallized iPS. The origin of the low‐temperature endothermic peak (annealing peak) has been investigated with TMDSC and FTIR spectroscopy and has been shown to be due to irreversible relaxation of the RAF. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3026–3036, 2003     

嵌入Y型分子筛中钯簇合成与结构的研究

经微波交换-焙烧-氢还原等过程制备了嵌入Y型分子筛中的钯簇化合物（Pd0Y）应用径向电子分布函数法（RedialElectronDistributionFunction），就其钯原子簇化合物进行了结构的研究．结果说明，嵌入Y型分子筛中的钯原子以A1型密堆积方式排列，聚集成约12大小的原子簇，嵌在Y型分子筛超笼之中．分子筛骨架的作用使族之间分立存在．它在超笼之中的占有率仅为0.06因此Pd0Y化合物既有纳米级金属钯的性能，又有分子筛固有的孔道结构特征．如此含有钯簇的分子筛化合物对一氧化碳完全氧化的反应具有超常的催化活性．     

A hyper-cross-linked polystyrene with nano-pore structure

Chloromethylated polystyrene (CMPS) beads were prepared by suspension polymerization of vinylbenzyl chloride (VBC), divinylbenzene (DVB) and styrene (St) in the presence of porogen. The same feed volume ratio of DVB leads to similar cross-linking degree for all CMPS, but decreasing VBC content provided a progressively reduced content of chloromethyl groups in each CMPS. Hyper-cross-linked polystyrene (HCLPS) beads were obtained by post cross-linking reaction of CMPS in dichloroethane (DCE) containing Friedel-Crafts catalyst. The role of porogen and its influence on nano-pore structure of HCLPS were investigated. The results showed that different types of porogen had significant effect on the nano-pore structure of the final products, such as specific surface area, average pore size and total pore volume. Using the mixture of toluene and cyclohexanol as inner porogen can yield the highest specific surface area for HCLPS beads. Moreover, higher amount of VBC lead to greater specific surface area and total pore volume. It was therefore indicated that nano-pore structure of HCLPS can be controllably prepared via changing porogen type and VBC concentration. Finally, the unprecedented swelling capacity was found for the hyper-cross-linked species derived from different porogen types.     

Effect of pressure and temperature history on volume relaxation of amorphous polystyrene

Control of volume changes with time has a critical industrial relevance for the production of objects made of thermoplastic materials (obtained, e.g., by injection molding), but this phenomenon is completely disregarded by commercial codes for simulation of processes. In this work, attention is focused on the relevance of thermomechanical history on volume relaxation at room conditions of an amorphous polystyrene. A set of data of volume relaxation of samples obtained in an extremely wide range of thermomechanical treatments was collected. Data were analyzed with the aim of applying a simplified model on the basis of the well‐known KAHR model, which describes the postprocessing volume relaxation of amorphous polymers by adopting a minimum number of material parameters. Despite the fact that only two relaxation times are considered, the model satisfactorily describes volume evolution (either contraction or expansion) at room conditions after a given thermomechanical treatment if an appropriate partition of free volume into two fractions is provided. Furthermore, in its present form that neglects the effect of pressure on volume relaxation, the model satisfactorily describes the effect of a given thermal treatment (at room pressure), starting from the melt, on both specific volume and its relaxation rate after treatment. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1526–1537, 2003     

Polymorphic crystal forms and morphology of syndiotactic polystyrene in miscible states

X-ray diffraction and optical microscopy characterization were performed to evaluate the phenomenon of alteration of polymorphism of syndiotactic polystyrene (s-PS) in the presence of other blending miscible polymers: poly(2,6-dimethyl-p-phenylene oxide) (PPO) or atactic polystyrene (a-PS). Both α and β crystal forms were observed in the neat s-PS sample, but only β-form crystal was found in miscible blends of s-PS with a-PS or PPO. The order and neighboring chain segments of neat s-PS are different from those of s-PS/PPO or s-PS/a-PS blends; thus, it is plausible that the greater randomness in the melt state of s-PS/a-PS or s-PS/PPO blends might be unfavorable for formation of α-form crystals from melts. The final spherulitic morphology the s-PS/a-PS or s-PS/PPO blends suggests that the amorphous-state miscibility of does not change much the spherulitic structure of s-PS. The radial growth rate is, in general, depressed with the presence of blending miscible polymers in s-PS of equal T_g or PPO of higher T_g. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2725–2735, 1998