聚丙烯中硫酯类抗氧剂的质谱分析

采用齐格勒-钠塔催化剂使丙烯催化聚合得到聚丙烯。聚丙烯树脂本身具有优良的性能,如机械强度好,易加工成型,质量轻,成本低等,但也存在一些缺陷,如由于聚丙烯结构中存在叔碳原子,在造粒加工、贮存和使用过程中,易受热、光、氧等的作用而降解,导致材料的性能降低。为了抑制和延缓聚丙烯的氧化降解,需要在造粒阶段加入抗氧剂。本文以一种聚丙烯树脂样品为研究对象,采用溶剂抽提法提取有机添加剂,并用柱层析法对添加剂进行了分离;利用EI-MS分析了添加剂的组成,其中通过谱图解析,鉴定出添加剂中含有硫酯类抗氧剂-硫代二丙酸二(十四)酯(DMTP),并用此类常用化合物进行了验证,分析结果对树脂牌号的开发具有指导意义。     

聚丙烯/层状硅酸盐纳米复合材料的制备、结构和性能

聚丙烯／层状硅酸盐纳米复合材料可通过丙烯单体插层聚合、聚丙烯溶液插层和聚丙烯熔融插层等方法制备，得到插层型或剥离型纳米复合材料，形成了与传统填充型聚合物复合材料不同的微观结构，其机械性能，热性能，阻隔性能和流变性能等明显提高，由于聚丙烯的非极性及层状硅酸盐纳米复合材料制备方法的特殊性，该研究具有一定的理论价值。     

聚丙烯表面光氧化的XPS研究

利用X射线光电子能谱(XPS)研究了光氧老化的聚丙烯(PP)表面的化学结构和组成变化。结果表明:(1)在受光氧老化的PP表面上形成了C-O、C=O及O-C=O官能团;(2)低分子抗氧剂在PP表面发生富集;(3)表面Ols/Cls强度比率可以较好地与冲击强度保留率相关联。     

生物降解高分子材料聚丁二酸丁二醇酯的改性研究进展

生物降解高分子材料被公认为是聚丙烯、聚乙烯等传统高分子材料造成"白色污染"的问题的重要解决方法之一。聚丁二酸丁二醇酯是重要的可生物降解的脂肪族聚酯之一,因与传统的聚丙烯、聚乙烯高分子材料具有相近的物理和力学性能,从而引起科学与工业界的广泛重视。然而,与大多数脂肪族聚酯一样,PBS材料也存在着加工、种类少、性能应用上的缺点。因此,对其通过改性拓宽用途范围的研究报道也随之增多。本文从化学、物理等改性的手段方法为着眼点,分类阐述了近些年来生物降解高分子材料聚丁二酸丁二醇酯改性研究现状与进展。     

掺铽聚丙烯薄膜的研究

合成了化学组成为Ｙ１－ｘＴｂｘＬ３和Ｌａ１－ｘＴｂｘＬ３（Ｌ＝Ｃ８Ｈ７Ｏ２）的两种荧光粉，将其掺杂到聚丙烯中，制得两种聚丙烯荧光薄膜，通过测试机械性能，微分扫描式量热法分析，紫外分光光谱和荧光光谱测定，研究膜的物理和荧光性能。结果表明：这两种掺铽聚丙烯膜在３６５或２５４ｎｍ紫外光激发下，都能发出黄绿色荧光。掺入Ｙ１－ｘＴｂｘＬ３的聚丙烯膜的荧光强度大于掺Ｌａ１－ｘＴｂｘＬ３的聚丙烯膜。     

成核剂对聚丙烯熔融行为的影响

成核剂对聚丙烯熔融行为的影响陈彦徐懋（中国科学院化学研究所高分子物理开放实验室北京１０００８０）关键词成核剂，聚丙烯，平衡熔点聚合物的熔融过程受分子量大小、分子量分布、分子链构型（等规度、分子结构单元的键接序列）、不同的结晶晶型、不同的热历史等...     

贵金属复合纳米粒子的研究进展

贵金属复合纳米粒子具有不同于单组分纳米粒子的独特的光、电和催化等物理与化学性能,是构筑新型功能复合材料的重要单元,在传感器、光学材料、催化剂及生物领域都有着重要应用,已成为当前纳米材料科学研究领域中的前沿和热点。本文主要评述了具有核壳、异质结构以及合金结构的贵金属复合纳米粒子的制备、物理与化学性能及应用等方面的研究进展。     

高分子的光氧老化

高分子在大气中暴露时,主要是以光氧老化为主。当高分子暴露在大气中时,可发生一系列物理的和化学的变化:     

高纯度长径比CaCO3晶须的制备

无机盐晶须材料是高技术新型复合材料中特殊的成员,它具有优良的耐高温、高热、耐腐蚀性能,有良好的机械强度、电绝缘性、轻量、高强度、高弹性模量、高硬度等特性。作为塑料、金属、陶瓷的改性增强材料时显示出极佳的物理、化学性能和优异的机械性能。     

功能纳米材料研究进展——唐智勇研究员及其团队专访

正功能纳米材料是化学、物理、生物和材料科学多学科交叉的前沿,是纳米科技发展的基础。功能纳米材料集中体现了小尺寸、精准控制、高集成度和强相互作用等现代科学技术发展的特点,是将量子力学效应工程化或技术化的最好载体之一,呈现独特的光、电、磁、机械和催化等性质,在物理、生物、化学和材料学领域中都有广泛的研究和应用前景。     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

液晶聚合物/柔性链聚合物共混体系相分离形态

利用元胞动力学方法在二维情况下对浓度、取向序参量的含时Ginzberg-Landau方程进行数值求解,研究了液晶聚合物/柔性链聚合物共混体系的相分离动力学,考察了浓度、取向有序过程的耦合对相分离形态的影响.结果表明,此耦合作用对相分离的时间进程以及相分离图样的空间排布都有影响.液晶聚合物的取向有序相当于增加了两组分间的不相容性而促进两相分离;两个序参量在热力学方面的耦合使液晶聚合物趋向于沿着界面方向取向,而动力学方面的耦合使液晶聚合物分子沿着其取向方向扩散,相分离图样的空间排布由这两种效应共同决定通过极化率张量的定义用数值方法模拟得到了相分离体系的小角光散射图样,结果表明,散射强度分布具有方位角依赖性,它是由浓度、取向序参量的空间变化共同决定的.     

氢气在炭狭缝微孔内吸附的预测

通过边界的平均场近似,推导二平板狭缝孔格子理论Ono-Kondo吸附等温方程.利用格子气模型特性和微观物理学理论,计算氢分子在石墨平面的最大吸附容量.比较由氢分子在石墨平面二典型聚集状态标定的Ono-Kondo方程,并用预测精度较高的方程计算了与文献相同条件下的吸附等温线.在比较了计算结果、试验结果和GCMC分子模拟结果后,对Ono-Kondo吸附等温方程的特点、理论基础作了分析,指出了方程的适用范围.     

Bimodality of molecular mass distribution of polydienes obtained under the action of dilithium initiators in hydrocarbon media: the reasons,mathematical simulations,and their experimental testing

Bimodal molecular mass distribution (MWD) of polymers, obtained upon polymerization of hydrocarbon monomers in the nonpolar media under the action of dilithium initiators, is the consequence of separation of the reaction mixture into two phases. Bifunctional /living/ oligomers produce the insoluble sediment due to tetrameric association of the lithium active sites (the swollen gel-fraction). Part of the active site remains in the solution (the solfraction). Difference in the concentrations of the active sites into the phases leads to difference between the propagation rates of the /living/ chains and, as a result, to Bimodal MWD. The mathematical model of polymerization in the two-phase system is proposed. Satisfactory agreement between the calculations and the experiments is shown for butadiene polymerization in heptane under the action of 1,4-dilithiumpentane. Regulation of MWD up to the complete elimination of bimodality is possible via the programmed dosage of monomer and solvent into the reactor.     

LOW DENSITY POLYETHYLENE/CLAY NANOCOMPOSITES MODIFIED BY ETHYLENE COPOLYMERS： EFFECTS OF FUNCTIONALIZED SEGMENTS ON MORPHOLOGY

Melt extrusion was used to prepare binary nanocomposites of ethylene copolymers and organoclay and trinary nanocomposites of low-density polyethylene （LDPE）, ethylene copolymer and organoclay. X-ray diffraction （XRD） and transmission electron microscopy （TEM） were used to analyze the structure of the clay phase and the morphology of the nanocomposites. Influences of the comonomer in the copolymer and the content of the copolymer on the morphology of the resulting nanocomposites were discussed. The binary and the trinary composites may form intercalated or exfoliated structures depending on the interaction between the copolymer and the clay layers and the content of the copolymer.     

Investigations of the Mechanism of Alternating Copolymerization with Charge-Transfer Interaction of the Monomers

The applicability of the method of Giese to the measurement of the influence of monomer reactivity is examined. The reaction of alkyl mercuric salts with sodium borohydride permits the production of alkyl (cyclohexyl and butyl) radicals. Since hydrogen radicals are present in high concentration, the addition of alkenes to the reaction mixture leads to radicals from the alkenes. Further addition of alkene (polymerization) can be nearly completely excluded in this way. The composition of the reaction products is determined by gas chromatography. The addition rate of the alkenes relative to styrene allows correlation with the e value of the Q-e scheme of Alfrey and Price. The method answers the question of how far addition of the monomer complex occurs in one step or as separate addition of both monomers during copolymerization in the presence of charge-transfer (CT) complexes of the monomers. The investigations are performed by using the styrene/acrylonitrile/ZnCl₂system, and it is demonstrated that the reactivity of the complexed     

Properties of aqueous solution of sodium glycocholate and a nonionic surfactant,and their mixtures

The micellar properties of aqueous binary mixed solutions of sodium glycocholate, NaGC, and octa-oxyethylene glycol mono-n-decyl ether, C₁₀E₈, have been studied on the basis of surface tensions, the mean aggregation number and the polarity of the interior of the micelles. The mean aggregation number, measured by steady state quenching method, decreased with the increase of the mole fraction of NaGC in the mixed system. The polarity of the interior, estimated by the ratio of first and third vibronic peak in a monomeric pyrene fluorescence emission spectrum, suggested that the hydrophobicity of intramicelles increased with the increase of the mole fraction of NaGC in the mixed system. These are considered to be caused by the differences in the chemical structure and the hydrophobic nature between NaGC and C₁₀E₈. The mean aggregation number and the polarity of the interior for each micelle near the CMC in lower total concentration of surfactants showed the tendency approaching those of pure micelle of the nonionic surfactant. This suggests that the ratio of NaGC in the initial micelles in the range of lower total concentration near the CMC is lower than that of the corresponding prepared mole fraction in the mixed system. This lower value was confirmed also from theoretical calculation of the ratio of NaGC at the CMC in the mixed micelle by regular solution treatment of Rubingh in the solution.     

Reliability and uncertainty in the estimation of p<Emphasis Type="Italic">K</Emphasis><Subscript>a</Subscript> by least squares nonlinear regression analysis of multiwavelength spectrophotometric pH titration data

When drugs are poorly soluble then, instead of the potentiometric determination of dissociation constants, pH-spectrophotometric titration can be used along with nonlinear regression of the absorbance response surface data. Generally, regression models are extremely useful for extracting the essential features from a multiwavelength set of data. Regression diagnostics represent procedures for examining the regression triplet (data, model, method) in order to check (a) the data quality for a proposed model; (b) the model quality for a given set of data; and (c) that all of the assumptions used for least squares hold. In the interactive, PC-assisted diagnosis of data, models and estimation methods, the examination of data quality involves the detection of influential points, outliers and high leverages, that cause many problems when regression fitting the absorbance response hyperplane. All graphically oriented techniques are suitable for the rapid estimation of influential points. The reliability of the dissociation constants for the acid drug silybin may be proven with goodness-of-fit tests of the multiwavelength spectrophotometric pH-titration data. The uncertainty in the measurement of the pK _a of a weak acid obtained by the least squares nonlinear regression analysis of absorption spectra is calculated. The procedure takes into account the drift in pH measurement, the drift in spectral measurement, and all of the drifts in analytical operations, as well as the relative importance of each source of uncertainty. The most important source of uncertainty in the experimental set-up for the example is the uncertainty in the pH measurement. The influences of various sources of uncertainty on the accuracy and precision are discussed using the example of the mixed dissociation constants of silybin, obtained using the SQUAD(84) and SPECFIT/32 regression programs.     

PHONONS IN POLYACENIC CHAINS

We have theoretically resolved phonon excitations in quasi-two-dimensional organic crystals of polyacenic semiconductor material which may be obtained by the pyrolytic treatment of phenol-formaldehyde resin. A model for studying the dynamical properties using three polyacene chains is proposed with the aim to present the vibrational properties of this structure. It employs the formalism of solid states in two dimensions which admit phonons. A simulation process of the two-dimensional lattice structure shows that elastic waves may explain the existence of vibrational modes in the frequency range 100-400 cm-1. The presence of acoustic and optical like phonons is discussed in terms of the elastic force constants. A hyperfine resonance structure is obtained. It allows the analysis of the dynamical evolution in thin films of polyacene. It is found that the behavior of the phonon density of states exhibits resonance between modes in the structure.     

MISCIBILITY AND MORPHOLOGY OF THIN FILMS OF BLENDS OF POLYSTYRENE WITH BROMINATED POLYSTYRENES： EFFECTS OF VARYING THE MOLECULAR WEIGHT, BROMINATION DEGREE AND ANNEALING

Thin films of incompatible polymer blends can form a variety of structures during preparation and subsequent annealing process. For the polymer blend system consisting of polystyrene and poIy(styrene-co-p-bromo-styrene), i.e., PS/PBrxS, its compatibility could be adjusted by varying the degree of bromination and the molecular weight of both components comprised, in this paper, surface chemical compositions of the cast and the annealing films were investigated by X-ray photoelectron spectroscopy (XPS) and contact angle measurement; meanwhile, surface topographical changes are followed by atomic force microscopy (AFM). In addition, substantial attention was paid to the effect of annealing on the morphologic variations induced by phase separation and/or dewetting of the thin film. Moreover, the influences of the molecular weight, Aw, as well as the brominated degree, x%, on the sample surface are explored systematically, and the corresponding observations are explained in virtue of the Flory-Huggins theory, along with the dewetting of the polymer thin film.