Structure development in melt‐spinning syndiotactic polystyrene and comparison to atactic polystyrene

Syndiotactic polystyrene (s‐PS) and atactic polystyrene (a‐PS) were melt‐spun into filaments. The s‐PS filaments exhibited increasing amounts of crystallinity and orientation with increasing drawdown ratio and spinline stress. The a‐PS filaments were amorphous but exhibited birefringence. The birefringence and Hermans orientation factors for a‐PS were proportional to this spinline stress. In ice water and at low drawdown ratios, the s‐PS is glassy or mesomorphic. At higher drawdown ratios and spinline stresses, it crystallized. The crystalline form was the zigzag TTTT hexagonal α‐form. The birefringence and orientation factors of the s‐PS filaments were higher than those of the a‐PS filaments and the difference of the birefringence increased with increasing spinline stress. Mechanical testing results showed that the Young's modulus and tensile strength generally increased with increasing spinline drawdown ratio for both a‐PS and s‐PS filaments. The elongation to break was enhanced for both materials by increased chain orientation. Polym. Eng. Sci. 44:2141–2147, 2004. © 2004 Society of Plastics Engineers.     

CO2 Hydrogenation to Methanol Over Cu/ZnO/Al2O3 Catalysts Prepared by a Novel Gel-Network-Coprecipitation Method

A novel gel-network-coprecipitation process has been developed to prepare ultrafine Cu/ZnO/Al₂O₃ catalysts for methanol synthesis from CO₂ hydrogenation. It is demonstrated that the gel-network-coprecipitation method can allow the preparation of the ultrafine Cu/ZnO/Al₂O₃ catalysts by homogeneous coprecipitation of the metal nitrate salts in the gel network formed by gelatin solution, which makes the metallic copper in the reduced catalyst exist in much smaller crystallite size and exhibit a much higher metallic copper-specific surface area. The effect of the gel concentration of gelatin on the structure, morphology and catalytic properties of the Cu/ZnO/Al₂O₃ catalysts for methanol synthesis from hydrogenation of carbon dioxide was investigated. The Cu/ZnO/Al₂O₃ catalysts prepared by the gel-network-coprecipitation method exhibit a high catalytic activity and selectivity in CO₂ hydrogenation to methanol.     

Synthesis and properties of poly(aryl ether sulfone ether ketone ketone) (PESEKK)

4,4′‐bis(Phenoxy)diphenyl sulfone (DPODPS) was synthesized by reaction of phenol with bis(4‐chlorophenyl) sulfone in tetramethylene sulfone in the presence of NaOH. Two poly(aryl ether sulfone ether ketone ketone)s (PESKKs) with high molecular weight were prepared by low temperature solution polycondensation of DPODPS and terephthaloyl chloride (TPC) or isophthaloyl chloride (IPC), respectively, in 1,2‐dichloroethane and in the presence of aluminum chloride (AlCl₃) and N‐methylpyrrolidone (NMP). The resulting polymers were characterized by various analytical techniques, such as FT‐IR, ¹H‐NMR, DSC, TG, and WAXD. The results show that the T_g and T_d of PESEKKs are much higher, but its T_m is lower than those of PEKK. The other results indicate that PESEKKs exhibit excellent thermostabilities at 300 ± 10°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 489–493, 2005     

单溴四苯基卟啉吸附在AgCl溶胶表面性质研究

合成了单溴四苯基卟啉—— 5 - (邻溴苯基 ) - 1 0 ,1 5 ,2 0 -三苯基卟啉 (H2 L) ,用元素分析 ,红外光谱、电子吸收光谱和氢核磁共振谱确定了其组成和结构。研究了 H2 L在醋酸中电子吸收光谱和在 Ag Cl溶胶上的表面化学反应。结果表明 ,单邻溴四苯基卟啉在冰醋酸中以二酸形式 H4 L2 + 和游离碱 H2 L形式存在 ,二者之间存在着电离平衡 :H4 L2 + =H2 L+2 H+ ;当 p H=7.0～ 1 1 .0时 ,H2 L在Ag Cl溶胶表面发生配位反应生成 Ag( ) L,并且溶液的 p H增大 ,配位反应的速率增大。     

Effect of thermal history on mechanical properties of polyetheretherketone below the glass transition temperature

Tensile properties of polyethertherketone (PEEK) have been studied at 125, 25, and ?100°C for thin films prepared with different thermal histories. Initial morphology was controlled by rate of cooling from the melt. Amorphous films resulted from quenching the melt, while semicrystalline films were obtained by cooling the melt at different rates, or by crystallization of the rubbery amorphous state. The films were characterized using density, X-ray scattering, differential scanning calorimetry, and infrared spectroscopy. Scanning electron microscopy was used to examine fracture surfaces. Degree of crystallinity and rate of cooling from the melt affected the tensile properties at all test temperatures. For films with nearly the same degree of crystallinity, those which were more slowly cooled from the melt fractured at the lowest strain. The amorphous films were most tough, drawing to 233% at ?100°C and to over 500% at 125°C. Films crystallized from the rubbery amorphous state had stress–strain behavior intermediate between that of the amorphous and melt-crystallized films at all test temperatures. Density measurements on the drawn material indicate that void formation occurs simultaneously with the formation of fibrillar crystals. Necking resulted in density increases for amorphous films, and density decreases for the semicrystalline films.     

Novel nitrogen‐containing epoxy resin. II. Cure kinetics by differential scanning calorimetry

The isothermal and nonisothermal cure behaviors of a novel nitrogen‐containing epoxy resin (XT resin) were studied by differential scanning calorimetry (DSC). Various kinetic parameters and details of cure process were obtained based on the Avrami theory. The results indicated that Avrami method is suitable for calculating the kinetic parameters up to the gel point at least. The apparent activation energy (E_a) for isothermal cure process was in agreement with that for nonisothermal cure process. E_a value in the early stage (78.5–81.0 KJ mol^?1) was about three times than that in the later stage (23.3–26.5 KJ mol^?1). The kinetic results from Avrami theory may present a combined effect of all factors, and which is helpful to understand the cure technique for XT–DDS system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3483–3489, 2006     

基于神经网络和过程机理的热流体系统仿真

构建了一种基于复合神经网络和过程机理特性的热流体系统仿真模型 .该模型在形式上为一种复合人工神经网络模型 ,保证了模型具有十分理想的仿真速度 ;在网络模型设计上较好地考虑了系统输入与输出间的物理基础 ,网络模型在一定程度上由常规的黑箱模型转化为“灰箱模型” ,网络的训练除了具有常规的输入、输出间的纯数值映射关系学习功能之外较好地体现了对象输入与输出间的物理机理学习 ,保证了网络模型具有良好的联想能力、外推能力和时间递推能力 .     

复合薄膜用水性聚氨酯-丙烯酸酯胶粘剂的合成

以聚醚二元醇、甲苯二异氰酸酯(TDI)、二羟甲基丙酸(DMPA)等为原料合成了聚氨酯预聚体,用丙烯酸羟丙酯(HPA)将其部分封端,制得一种水性聚氨酯丙烯酸酯分散体,再加入乙烯基单体进行自由基引发聚合,制备出水性聚氨酯-丙烯酸酯(PUA)复合乳液。用红外光谱仪(FTIR)、差示量热扫描仪(DSC)、热重分析(TG)、马尔文粒度分析等测试手段,对合成产物进行了结构和性能表征。研究了软硬段质量比、亲水基团含量、丙烯酸酯单体的加入对PUA乳液性能的影响。结果表明,m(软段)∶m(硬段)=2∶1,m(PU)∶m(PA)=4∶1,—COOH质量分数为2.8%,以该乳液配制的胶粘剂应用于包装用CPP/CPP薄膜、OPP/VMOPP薄膜的剥离强度分别达31.9N/m和28.1 N/m。     

低热固相合成磷酸铵铜微肥及信噪比控制合成

对合成缓溶磷酸铵铜多元微肥的新方法进行了研究，以聚乙二醇-400 （PEG-400）为模板，CuSO4•5H2O和(NH4)3PO4•3H2O为原料，用低热固相反应一步法成功合成得到磷酸铵铜。用产物XRD图谱数据计算得到的信噪比作为试验的考察指标，试验中应用了均匀设计试验法及数据挖掘技术，在数据挖掘成果的指导下进行了试验。试验结果表明，用最优工艺条件合成得到的产物为51nm的NH4CuPO4 ∙H2O。该合成方法除了得到微溶的磷酸铵铜外，还得可溶的硫酸铵或者硫酸氢铵，这些产物均是肥料，故在实际应用中，用本文的合成法合成磷酸铵铜微肥时，无需分离，其产物混合物就可以作为肥料作用了，不仅合成的工艺甚为简洁，而且生产过程没有废水的产生，无论是从工艺上，还是环保上均比液相法具有优势，是一种颇具工业应用前景的合成法。     

Isothermal crystallization kinetics and morphology development of isotactic polypropylene blends with atactic polypropylene

The crystallization kinetics and morphology development of pure isotactic polypropylene (iPP) homopolymer and iPP blended with atactic polypropylene (aPP) at different aPP contents and the isothermal crystallization temperatures were studied with differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy. The spherulitic morphologies of pure iPP and larger amounts of aPP for iPP blends showed the negative spherulite, whereas that of smaller amounts of aPP for the iPP blends showed a combination of positive and negative spherulites. This indicated that the morphology transition of the spherulite may have been due to changes the crystal forms of iPP in the iPP blends during crystallization. Therefore, with smaller amounts of aPP, the spherulitic density and overall crystallinity of the iPP blends increased with increasing aPP and presented a lower degree of perfection of the γ form coexisting with the α form of iPP during crystallization. However, with larger amounts of aPP, the spherulitic density and overall crystallinity of the iPP blends decreased and reduced the γ‐form crystals with increasing aPP. These results indicate that the aPP molecules hindered the nucleation rate and promoted the molecular motion and growth rate of iPP with smaller amounts of aPP and hindered both the nucleation rate and growth rate of iPP with larger amounts of aPP during isothermal crystallization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1093–1104, 2007