普适平衡缩聚方程的理论处理

从化学平衡角度严格推导出了普适的平衡缩聚方程。首次明确得到了起始官能团浓度、残留小分子浓度及摩尔系数同平衡常数一起影响＾－Ｘｎ的结论。     

普适平衡缩聚方程的理论处理

从化学平衡角度严格推导出了普适的平衡缩聚方程。首次明确得到了起始官能团浓度、残留小分子浓度及摩尔系数同平衡常数一起影响Ｘｎ的结论。     

异丙醇铝水解缩聚动力学

利用水含量在线测定实验与计算机模拟相结合的方法研究了异丙醇铝水解-缩聚动力学。通过对不同异丙醇铝和水物质的量之比和不同温度下反应获得的水含量随时间变化曲线进行分析,采用非线性拟合方法分别求得异丙醇铝水解、脱水和脱醇缩聚的反应速率常数及活化能。利用实验结果及建立动力学模型,由龙格库塔法计算异丙醇铝的水解缩聚过程,并求得不同反应温度和初始反应物浓度比条件下各官能团浓度与反应终止时间的关系,进而获得反应终止时间与反应温度、初始反应物异丙醇铝浓度、异丙醇铝和水物质的量之比之间的关系方程,为制备低成本高纯氧化铝提供有价值的参考。     

PET缩聚过程脱挥方式比较——抽真空及通氮气

抽真空及通氮气是 Ｐ Ｅ Ｔ缩聚过程脱除小分子的两种方式, Ｐ Ｅ Ｔ 间歇缩聚实验研究表明：通氮气脱挥时聚合度一直上升,而抽真空脱挥时聚合度趋向某定值;脱挥速度与通氮位置有关;通氮气脱挥得到的聚合物比抽真空脱挥得到的色泽白。     

长链聚酰胺酸的缩聚动力学研究

以长链二胺4，4’-二(4-氨基苯氧基)二苯砜(BAPS)为单体，在N，N'-二甲基甲酰胺(DMF)中分别与3种二酐于室温下反应，合成了3种长链聚酰胺酸(PAA)。利用GPC研究了PAA相对数均聚和度(Xn)及其分布随缩聚时间的变化关系。结果表明：该反应为自催化逐步缩聚反应，反应级数为三级；在初始阶段，缩聚速率常数随二酐电子亲和性(EA)的递增而增加。     

聚酯固相缩聚技术进展

简略地介绍了聚酯固相缩聚的起源、演变和发展趋势,剖析各种聚酯团相聚合设备的优点和弊端,着重介绍了美国H—Bepex公司第三代结晶器——串联Disc盘状结晶器和第四代结晶器——远红外结晶器,这种远红外结晶器既能有效地避免切片的粘结又能有效地抑制粉尘的产生。并就氮气净化技术对目前国际上采用的种种方法进行了简明扼要的比较。     

尼龙-1010前期缩聚动力学

研究了尼龙-1010盐敞开系统熔融缩聚的前期动力学.结果表明,癸二胺挥发程度低,敞开系统熔融缩聚工艺可行,其动力学符合拟不可逆二级反应机理,活化能为82.7 kJ•mol^-1,尼龙-1010缩聚速率远比密闭体系的尼龙-66快.     

对苯二甲酸与乙二醇缩聚反应过程判别———临界聚合度的研究

对苯二甲酸与乙二醇缩聚反应过程是一反应与传质串联过程，当聚合度小于Ｐｎｃ时，反应为过程控制步骤。通过静止膜实验，在温度２７２～２８３℃，压力１３３～１０６６４Ｐａ范围内建立了与温度、压力的关系式，用于确定缩聚过程处于反应控制的临界聚合度     

CDP固相缩聚的研究

对N_2保护下CDP的固相缩聚进行了基础研究,得出了CDP固相缩聚的一般规律,并对实验结果进行了讨论,与常规PET固相缩聚的一些规律进行了比较,同时还比较了不同反应氛围下CDP的分子量变化情况.     

综述聚磷酸铵平均聚合度测定方法

阻燃剂聚磷酸铵平均聚合度的测定是其结构表征的一个重要内容,介绍对其测定的常用方法及其原理,比较各种方法的优缺点,总结各种方法可准确测定的适用范围。     

The Study of Template Polymerization Kinetics of Multiacrylate

The synthesis of poly(2-acryloyloxyethyl methacrylate) has been performed followed by its polymerization. The kinetics of photochemically initiated template polymerization resulting in a ladder polymer has been examined. Global reaction rate constants within 293–313K, global activation energy, activation entropy and initiation rate have been determined. It has been found that in comparison with a conventional polymerization process of methyl methacrylate, the template process is characterized by reduced activation energy and entropy. It has been observed that in the polymerization of multimonomer (when monomer units are linked with the template by covalent bonds), there are similar regular relationships to those in the template polymerization of methyl methacrylate, where the only forces acting between the template and the growing macroradical are intermolecular. © of SCI.     

Polycondensation kinetics of poly(phenylene ether sulphone)

The synthesis of poly(phenyl ether sulphone) (from the potassium salts of 4,4′-dihydroxydiphenyl sulphone and 4,4′-dichlorodiphenyl sulphone or 4-chloro-4′-hydroxydiphenyl sulphone) was found to have different reaction kinetics according to the route used. By discriminating between rate constants (between monomer/monomer, monomer/polymer, polymer/polymer) a set of multi-parameter kinetic equations is obtained. Experimental and simulated values of the individual rate constants were in good agreement (for both the reaction rate and molecular weight distribution). The polycondensation reaction can be analysed, in terms of the component reactions.     

Polycondensation between p‐dibromobenzene and m‐dibromobenzene

NiCl₂ (bpy)‐catalyzed polycondensation between p‐dibromobenzene and m‐dibromobenzene was carried out under various conditions. With the polycondensation, a series of copolymers with number‐average molecular weights of 2400 (by gel permeation chromatography with polystyrene standards) was formed, and some samples had good solubility in organic solvents. The IR spectra and the ultraviolet spectra measured in a tetrahydrofuran (THF) solution of the copolymer showed that there were p‐phenylene and m‐phenylene units in the copolymer. According to analyses with differential scanning calorimetry, thermogravimetric analysis, and X‐rays, with an increasing molar ratio of m‐phenyl units in the copolymer, the glass‐transition temperature, the temperature of viscous flow, and the crystallizability of the polyphenylene copolymer decreased. The fluorescence spectra of the copolymer measured in a THF solution showed an emission maximum at 373–376 nm, whereas the maximum shifted to 436.6 nm for the film. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2210–2215, 2003     

Polymerization shrinkage,stress, and degree of conversion in silorane‐ and dimethacrylate‐based dental composites

To compare two kind of resin‐based dental composites, the polymerization shrinkage, contraction stress (CS), and degree of conversion (DC) of four dimethacrylate‐based and one silorane‐based composite were investigated. To determine shrinkage, the composites were packed, respectively, into a cylindrical cavity in human teeth and imaged using X‐ray microcomputed tomography to determine the precise volume before and 30 min after photopolymerization. To determine CS, the sample was applied in a similarly sized cylinder in a universal testing machine and monitored for 30 min. FTIR spectroscopy was used to determine DC. The volumetric shrinkage (range: 1.1–3.1%) and maximum CS (range: 1.2–3.5 MPa) differed significantly among the tested composites but not the final DC (range: 62.3–69.1%). The silorane‐based composite displayed the lowest volumetric shrinkage and CS of all composites. No correlation was observed between the stress and volumetric shrinkage values of the dimethacrylate‐based composites. A moderate correlation was found between stress and DC (r = 0.836), which was significant at 20 and 40 s. The silorane‐based composite exhibited superior shrinkage behavior compared with conventional dimethacrylate composites with comparable polymerization kinetics. The CS was dependent on multiple variables, including the volumetric shrinkage, DC, and curing rate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

正丙醇脲醛树脂的合成

本文论述了丙醇脲醛树脂的合成,并对合成条件进行了探讨,采用本法制备的产品,效果好、贮存稳定。     

Polycondensation of tetramethyldisiloxane 1,3-diol catalyzed by trifluoromethanesulfonic acid

The kinetics of polycondensation of tetramethyldisiloxane 1,3-diol (HD₂OH) have been followed by stopping the reaction at increasing times (by neutralization of the acid and trimethylsilylation of the silanol end-groups). Analyses of the linear and cyclic oligomers and of the higher polymer have been made by gas–liquid chromatography and by steric exclusion chromatography. At the beginning of the reaction (e. g. between 1 min and 1 h) the main products are linear oligomer H(D)_2nOH and D₄ (formed by cyclization of HD₄OH). There are only very small amounts of large cycles. Linear high polymer is then formed slowly together with increasing amounts of cycles D₅, D₆, D₇, …, formed by backbiting reactions. After 24h, the yield of D₄ is 40–50% and that of linear polymer 40–30% (M_peak × 10⁴–10⁵). With disilanol concentration 0.45–0.9 mol liter^?1 and CF₃SO₃H concentration about 10^?3 mol liter^?1, the reaction is very rapid during 1–2 min and the medium becomes heterogenous with the formation of an inverse water emulsion. The reaction then slows down considerably, most of the hydrated acid being trapped in the water droplets. Silanol consumption is second order in [SiOH] and first order [TfOH]_o. Polymerizations made in polar and non-polar solvents have similar rates, which however increase moderately in the order toluene<1,2-dichloro-ethane<dichloromethane, this corresponding to an increasing solubility of the hydrated acid in these solvents. Polycondensation occurs in the organic phase near the interface, either by esterification of silanol followed by heterccondensation or by homocondensation catalyzed by the hydrated acid (or both).     

聚醋酸乙烯平均聚合度的实时在线监测

基于Hagen Poiseuille方程 ,结合聚合物溶液粘度与其浓度、温度及聚合的定性关系 ,提出了一种新的实用的在线检测聚醋酸乙烯平均聚合度的方法 ,给出了该聚合度与现场易得参数的定量关系。涉及参数包括管道中横向抽样段的压差、通过选定截面的流量、溶液的浓度和温度。运用此关系得到的线性回归方程来实时在线预测聚合度 ,基本满足工厂的误差要控制在 - 5 0～ 5 0℃的要求 ,对生产过程有实际的应用价值     

高聚合度聚乙烯醇的制备

采用醋酸乙烯酯为单体,以OP-10和十二烷基硫酸钠为复配乳化剂,偶氮二脒基丙烷盐酸盐为引发剂,通过正交实验研究了乳液聚合法制备高聚合度聚醋酸乙烯酯的最佳工艺条件.通过单因素实验验证了最佳工艺条件的可靠性,并分析了乳化剂用量、引发剂用量和反应温度对醋酸乙烯酯平均聚合度的影响规律.在最佳工艺条件下制得了聚合度为5 100的聚醋酸乙烯酯,经醇解得到了聚合度为4 800的聚乙烯醇.     

论高聚物合成工艺学的教学改革

"高聚物合成工艺学"是高分子材料科学与工程专业的核心专业课程,具有十分重要的地位。文章介绍了高聚物合成工艺学的课程特点。并根据教学实践提出了基于学生基础、适应社会发展、侧重实践性环节以及教学方式灵活、多样化的教学改革思想。