非极性烷烃溶剂在聚乙烯膜中无限稀释扩散系数的测定

气相色谱法研究小分子溶剂与聚合物材料之间的相互作用是一种快速、准确、方便的方法,该方法可以用来研究多种小分子溶剂在聚合物中的溶解和扩散行为.通过气相色谱法测定了3种小分子烷烃溶剂(正庚烷、正壬烷和正癸烷)在固定液聚乙烯中的保留时间和半峰宽,用vanDeemter模型进行数据处理,得到3种小分子在聚乙烯膜中的无限稀释扩散系数.     

水、甲醇和乙醇溶剂在PVA膜材料中无限稀释扩散系数测定

用气相色谱法研究小分子溶剂与聚合物材料之间的相互作用是一种快速、准确和方便的方法,该方法可以测量多种小分子溶剂在聚合物中的溶解和扩散行为.采用该方法测定了水、甲醇、乙醇在固定液PVA中的保留时间和半峰宽,运用van Deemter模型进行数据处理,得到了上述几种小分子在PVA膜材料中的无限稀释扩散系数,获得了有意义的结果.     

超临界二氧化碳中不同聚合物吸附小分子的比较

研究了超临界二氧化碳中聚氨酯,乙烯醋酸乙烯共聚物和低密度聚乙烯等3种聚合物对几种小分子的吸附作用,观测了吸附小分子后的聚合物的形态变化以及无水乙醇和乙酸乙酯在这3种聚合物中的解吸,实验表明低密度聚乙烯吸附能力较差,不适作吸附的基体材料,而聚氨酯,乙烯醋酸乙烯共聚物吸附小分子能力较强。小分子在聚合物中按时间的自然指数形式递减规律解吸,解吸扩散系数数量级达10-7cm2/s。     

三种芳烃溶剂在低密度聚乙烯膜材料中无限稀释扩散系数的测定

用气相色谱法测定了苯、甲苯和乙苯在固定液低密度聚乙烯中的保留时间和半峰宽,运用vanDeemter模型进行数据处理,得到3种芳烃小分子在低密度聚乙烯膜材料中的无限稀释扩散系数.     

液-固扩散法制备可交联聚乙烯

基于小分子在聚合物中的扩散原理,采用液-固扩散法,将液态小分子交联剂、抗氧剂从固态低密度聚乙烯(LDPE)颗粒表面扩散到内部,实现小分子助剂与聚合物的均匀、温和混合,得到品质优良的可交联聚乙烯.采用DSC、FTIR等手段,分析不同扩散条件时LDPE颗粒表层和芯层的交联热焓、特征吸收峰强度的变化规律,探索小分子助剂向聚合...     

空气在二甲基硅油和液压油中的溶解度

对于诸多工程运用场合, 获得空气在硅油以及液压油中溶解度可靠的数据至关重要. 针对已有测量装置及方法的不足, 建立了一种基于理想气体状态方程来确定气体溶解量的新型精密活塞式装置. 获得了温度为293.2及353.2 K, 压力在0-350 kPa范围内, 空气在500cSt 二甲基硅油中的本生溶解度表达式. 测量了298.2 K时20cSt二甲基硅油及国产32#抗磨液压油在多种气相压力下的本生溶解度. 精度及可靠性分析表明实验数据的误差范围为6%. 本生溶解度与气相压力呈较好的线性关系, 以摩尔分数表示的溶解度与压力呈非线性关系, 但可用Krichevsky-Ilinskaya方程拟合. 发现空气在相对分子质量差异很大的两种二甲基硅油中的本生溶解度很接近, 由此提出, 对于小分子的非极性溶质在聚合物溶剂中的溶解度, 用聚合物单体的摩尔数而不是聚合物分子摩尔数来表示摩尔浓度更有利于实验数据的外推和工程应用. 对于相对分子质量差别较大或无法确定相对分子质量的溶剂, 工程应用中适宜采用本生溶解度.     

手性溶剂诱导非手性物质手性的研究进展

手性溶剂诱导非手性物质产生手性是目前合成手性物质的主流方法之一。与传统的手性物质合成方法相比,手性溶剂诱导法不仅避免了使用昂贵的手性试剂,还能扩大合成手性物质的结构范围,具有潜在的应用前景。目前,手性溶剂诱导方法适用范围已经涵盖了有机小分子、低聚物和聚合物体系。本文主要对手性溶剂诱导方法发展的历史背景,手性溶剂诱导小分子及低聚物的手性,手性溶剂诱导非手性聚合物产生超分子手性,主要包括π-共轭聚合物和σ-共轭聚合物这几个方面展开了综述。     

复杂样品痕量极性小分子化合物的样品前处理及分析方法研究进展

核苷、胺、氨基酸等极性小分子化合物是生物、食品、环境等领域重要的研究对象,但各种复杂基体中痕量极性小分子的分离分析需要高效的前处理介质和技术以及快速灵敏的分析方法。本文综述了硅胶材料、有机聚合物、炭材料和硼酸材料等样品前处理分离介质及反相液相色谱、亲水作用色谱等分析方法在复杂样品痕量极性小分子化合物分析中的应用,并展望了其发展趋势。     

非极性溶剂微波萃取-气相色谱-质谱法测定白豆蔻中挥发油成分

提出了非极性溶剂微波萃取-气相色谱-质谱法测定白豆蔻中的挥发油成分的方法。优化的试验条件如下:①微波吸收介质为0.35g石墨粉;②提取溶剂为正己烷;③样品质量与溶剂容积之比为2g比25mL;④提取时间为30min。在气相色谱分离中用DB-5石英毛细管柱为固定相,在质谱分析中采用全扫描检测模式。以α-甲基苯甲醇丙酸酯为内标物。方法用于白豆蔻样品的分析,共鉴定出60种挥发性化学成分,主要化合物为桉油精(70.34%)、β-蒎烯(6.81%)、α-松油醇(3.36%)和α-蒎烯(2.54%)等。     

凝胶渗透色谱/气相色谱-质谱法测定塑料玩具中16种多环芳烃

建立了塑料玩具中16种多环芳烃（PAHs）的凝胶渗透色谱-气相色谱-质谱测定方法。称量0.25 g塑料材质样品，以四氢呋喃为溶剂溶解，采用凝胶渗透色谱实现多环芳烃小分子与塑料聚合物大分子的分离净化，以气相色谱-质谱法对PAHs进行定性、定量检测。16种PAHs的检出限为0.06～0.12 mg/kg，在1.0～30.0μg/mL范围内具有良好的线性关系，线性相关系数不小于0.998，基体加标回收率为70%～92%，相对标准偏差均不高于15%(n=7)。检测方法简便、快速、灵敏度高，适用于不同聚合物塑料中PAHs的测定。     

Measurement of the infinite dilution diffusion coefficients of small molecule solvents in silicone rubber by inverse gas chromatography

The infinite dilution diffusion coefficients of n-hexane, n-heptane and n-decane in crosslinked silicone rubber with different crosslinking agent concentrations were measured in the temperature range of 348.15 K-368.15 K by inverse gas chromatography. The crosslinked silicone rubber was obtained by dissolving PDMS prepolymer, crosslinking agent and catalyst in n-heptane solvent and characterized by FTIR spectra. The Van Deemter equation was used to determine diffusion coefficients from the variation in chromatographic peak width with carrier gas flow rate. The good linear relation indicated the Van Deemter equation used in this work was reliable. The influences of small molecule solvent, crosslinking agent concentration and temperature on the infinite dilution diffusion coefficient were investigated. The results showed that the infinite dilution diffusion coefficient decreased with an increasing number of CH₂ group in the alkane series. The increase in crosslinking agent concentration resulted in decrease of the infinite dilution diffusion coefficient. The infinite dilution diffusion coefficient increased with the rising of temperature. The interdependence on the infinite dilution diffusion coefficient and temperature accorded with Arrhenius equation well. Diffusion constant and activation energy obtained from the Arrhenius equation provided straight lines with the specific critical volume and crosslinking agent concentration.     

Temperature and concentration dependence of diffusion coefficients in ethylene–propylene-diene copolymers

Self-diffusion and partition coefficients were measured for two commercial ethylene–propylene-diene copolymers (EPDM) and five solvents at infinite dilution using inverse gas chromatography. Mutual diffusion coefficients for solvents in EPDM also were measured for finite concentration using gravimetric sorption for three of the solvents. From the inverse gas chromatography experimental values for self-diffusion coefficients were obtained. Free-volume parameters were obtained through regression of the self-diffusion coefficient as a function of temperature. Mutual diffusion coefficients as a function of concentration were predicted using free volume theory and compared with experimental data obtained using gravimetric sorption. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1713–1719, 1998     

Diffusion and partition coefficients of small organic solvents in molten miscible polymer blends: Correlations with thermodynamic interactions

The transport properties of small organic molecules in molten poly(vinyl chloride) (PVC)/atactic poly(methyl methacrylate) (PMMA) blends and their homopolymers were studied with inverse gas chromatography. The elution profiles resulting from various organic solvents and different experimental conditions were used for measuring diffusion and partition coefficients. With the van Deemter equation and retention volumes at infinite dilution, diffusion coefficients of 10^?7 to 10^?8 cm²/s and partition coefficients of 10–50 were calculated. The dependence of the diffusion and partition coefficients on experimental variables such as the blend concentration, temperature, and solute nature was examined. The presence of PMMA in PVC blends affected the sorption behavior of the PVC matrix up to a certain concentration. Beyond that, it was hard to derive any composition–diffusivity dependence. On the contrary, the diffusion and partition coefficients were greatly influenced by changes in the temperature and by the nature of the solute. For those solutes (e.g., chlorinated hydrocarbons) showing stronger interactions with polymer blends (higher negative values for the Flory–Huggins interaction parameter χ₁₍₂₃₎), higher diffusion and partition coefficients were obtained. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 267–279, 2004     

四臂星形聚苯乙烯在良溶剂和0溶剂中分子扩散的光子相关光谱的研究

用光子相关光谱研究了四臂星形聚苯乙烯在良溶剂(四氢呋喃THF)和θ溶剂(环己烷CH)中扩散系数与溶剂的浓度和温度的依赖关系。用累积量方法分析光子相关数据给出了多分散样品的Z均扩散系数。在θ溶剂中,高于或低于θ温度时,聚合物在溶液中的分子扩散分别表现出具有在良溶剂与不良溶剂中的行为。外推浓度至零,得到无限稀时不同温度的分子扩散系数,借助Stokes-Einstein方程,给出了聚合物的流体力学半径。通过InD对I/T作图,得到了星形聚苯乙烯在THF与CH中的扩散活化能。     

Phase equilibrium and diffusion of solvents in polybutadiene: A capillary‐column inverse gas chromatography study

The capillary‐column inverse gas chromatography method was used to measure the diffusion and partition coefficients of ethylbenzene, styrene, and acrylonitrile in polybutadiene (PBD) at infinite dilution of the solvents. Experiments were performed over a temperature range of 50–125 °C. At temperatures well above the glass‐transition temperature of PBD, the diffusivities were correlated using an Arrhenius expression. The Arrhenius parameters in turn were intercorrelated and shown to be a function of the occupied volume, thus providing a method for predicting the diffusion of other solvents in the same polymer. Further, the activation energy was predicted using the Duda‐Vrentas free‐volume approach. The activation energy thus obtained was compared with the activation energy of the Arrhenius approach. The weight‐fraction activity coefficient data were compared to the predictions of the group contribution, lattice‐fluid equation‐of‐state, and the UNIquac Functional‐group Activity Coefficient (UNIFAC) free‐volume models. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1046–1055, 2002     

反气相色谱测定双阳离子型离子液体的溶解度参数

采用反气相色谱法,于343.15 K到363.15 K温度下测定了双阳离子型离子液体1,10-双(N-甲基咪唑鎓)癸烷六氟磷酸盐［C10(MIM)2］［PF6］2的溶解度参数。以正辛烷、正十二烷、正十四烷和正十六烷为探针溶剂,计算了探针溶剂的特性保留体积(V0g)、摩尔吸收焓(ΔHS1)、无限稀释摩尔混合焓(ΔH∞1)、摩尔蒸发焓(ΔHv)、无限稀释活度系数(γ∞12)以及探针溶剂与［C10(MIM)2］［PF6］2的Flory-Huggins相互作用参数(χ∞12),测得该离子液体的溶解度参数(δ2)为15.01 (J\5cm~3)1/2。这一结果对研究离子液体的溶液性质和应用有指导作用。     

An Alternative Method for Correlation and Evaluation of Mutual Diffusion Coefficients of Solutes in Organic Solvents at Infinite Dilution

Based on the linear free energy relationships theory and empirical equations, correlations of mutual diffusion coefficients of solutes in organic solvents at infinite dilution at various temperatures are proposed. Four homologues in 743 binary systems have been regressed and correlation equations for the diffusion coefficients are obtained. The mean relative deviations of the four equations are 8.63%, 8.57%, 2.96%, and 4.85%, and all of the squared correlation coefficients (R²) are larger than 0.96, indicating that the fittings are good. The results reveal that a simple form of the equation exhibits high estimation accuracy, definite theory meaning, wide applicability and wide temperature range. This study successfully combines macroscopic physical properties of substances with their molecular microstructure, providing an alternative approach for calculating of mutual diffusion coefficient.