Structural characterization of reactor blends of polypropylene and ethylene‐propylene rubber

Blends of isotactic polypropylene (PP), ethylene‐propylene rubber copolymer (EPR), and ethylene‐propylene crystalline copolymer (EPC) can be produced through in situ polymerization processes directly in the reactor and blends with different structure and composition can be obtained. In this work we studied the structure of five reactor‐made blends of PP, EPR, and EPC produced by a Ziegler‐Natta catalyst system. The composition of EPR was related to the ratio between ethylene and propylene used in the copolymerization step. The ethylene content in the EPR was in the range of 50–70 mol %. The crystallization behavior of PP and EPC in the blends was influenced by the presence of the rubber, and some specific interactions between the components could be established. By preparative temperature rising elution fractionation (P‐TREF) analysis, the isolation and characterization of crystalline EPC fractions were made. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2155–2162, 2004     

Effect of bentonite on the physical properties and drug‐release behavior of poly(AA‐co‐PEGMEA)/bentonite nanocomposite hydrogels for mucoadhesive

A series of nanocomposite hydrogels for mucoadhesive were prepared from acrylic acid, poly(ethylene glycol) methyl ether acrylate, and intercalated bentonite clay by photopolymerization. The microstructures were identified by X‐ray diffraction (XRD). Results showed that the swelling ratio for the present nanocomposite hydrogels decreased with an increase of bentonite, whereas the gel strength and Young's modulus of the present gels increased with an increase of bentonite. However, the adhesive force of the present gels did not decrease with an increase of bentonite. XRD results indicated that the exfoliation of bentonite was achieved in the xerogels and swollen gels. Finally, the drug‐release behaviors for these gels were also assessed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2934–2941, 2004     

The Solid State Postcondensation of PET, 3

Summary: It was demonstrated that it is possible to produce prepolymers with a number‐average degree of polymerisation on the order of 5–40 directly in a liquid‐liquid dispersion in less than three hours. It was also shown that prepolymers made via this route and rapidly crystallised by the addition of a dispersant at ambient temperature are more porous than prepolymers made in an industrial liquid melt process.

SEM micrograph of prepolymers pLL‐PTA with \overline {DP} _{\rm n} = 28, d_p ∈ 63–125 μm.     

从催化裂化干气中提取乙烯

目前国内乙烯资源短缺,从催化裂化干气中提取乙烯是减少浪费、提高乙烯产量的有效途径。本文介绍了深冷分离、吸收分离、水合物分离、膜分离、吸附分离以及联合工艺等分离技术,并对一些主要分离工艺进行了技术经济分析,指出吸附分离工艺具有较好的工业应用前景。     

低黏二氰胺类离子液体乙烯汽液相平衡研究

从工业废气中回收分离乙烯（C₂H₄）具有重要意义,选用了三种低黏度二氰胺类离子液体,分别测定了293.15~333.15 K下其密度、黏度等物化性质,研究了其对乙烯（C₂H₄）吸收性能。采用非随机（局部）双液体模型（NRTL）关联了三种二元体系溶解度数据,实验值与计算值的平均相对偏差均小于3%。结果表明,低黏度二氰胺类离子液体对C₂H₄气体吸收性能良好,其中阳离子侧链长度增加和羟基功能团引入可增强对C₂H₄溶解度。同时,离子液体1-丁基-3-甲基咪唑二氰胺盐（[Bmim][DCN]）经过3次的吸收解吸循环,仍可以保持较好的C₂H₄吸收性能,表明该离子液体循环稳定性好,而1-丁基-3-甲基咪唑二氰胺盐（[Bmim][DCN]）对乙烯吸收量较高,具有作为C₂H₄吸收剂的潜力。     

成核剂对PET结晶行为及形态结构的影响

系统地研究了四种成核剂:N-A、液晶VectraA950、滑石粉(Talc)、乙撑双硬脂酰胺(EBS)对聚对苯二甲酸乙二醇酯(PET)的结晶行为的影响。采用差式扫描量热仪(DSC)研究了PET/成核剂复合体系的非等温结晶行为,通过小角激光散射(Sals)、X衍射(XRD)对PET/成核剂复合体系的晶体尺寸和晶体结构进行了研究。结果表明,引入成核剂后,PET的结晶行为有较大改善,结晶峰向高温方向移动,且变尖锐,结晶尺寸变小,结晶度提高,除EBS外,均使PET结晶诱导时间减少。在这四种成核剂中,离子聚合物成核剂N-A成核效果最好。     

化学交联聚乙二醇水凝胶的制备方法

对化学交联聚乙二醇基水凝胶的研究进展进行了综述.介绍了该类水凝胶的制备方法,包括几种常见的前体制备方法和常用的交联方法,并讨论了影响水凝胶溶胀性能和力学性能的几种因素.     

PET/PTT共混体系的研究进展

综述了PET/PTT共混体系的国内外发展现状,重点对共混体系的相容性,共混体系的结构形态,熔融结晶行为和结晶动力学和结晶熔融行为进行了论述,并对其发展前景进行了展望。     

复合成核剂对PET结晶速率和特性黏数的影响

采用差示扫描量热分析仪和乌氏黏度计研究了不同成核剂及其复配对聚对苯二甲酸乙二醇酯（PET）结晶速率和特性黏数的影响。结果表明,复合成核剂对于提高PET成核结晶速率[半结晶时间（t1/2）为32.3~45.3 s]的效果优于单一成核剂（t1/2为42.9~57.9 s）;同时部分复合成核剂能有效减小PET特性黏数的降低幅度。     

含聚乙二醇长侧链的无磷阻垢剂合成与阻磷酸钙性能

采用过硫酸铵为引发剂,丙烯酸(AA)和烯丙基聚乙二醇硫酸铵(AS10,10是聚乙二醇聚合度)为单体制备了一种用于阻磷酸钙垢的无磷阻垢剂AA/AS10,并利用红外光谱对其结构进行了表征。通过单因素法确定了合成反应的最佳工艺:单体AS10与AA的质量比为2∶1,引发剂用量为反应物单体总质量的3%、反应温度为80℃、聚合时间为1.5 h。同时考察了阻垢剂AA/AS10用量对共聚物阻磷酸钙垢性能的影响。结果表明,阻垢剂AA/AS10用量存在临界值效应,在临界值6 mg/L时,阻磷酸钙垢率约92%。扫描电镜研究表明,阻垢剂AA/AS10减小了磷酸钙固体颗粒的尺寸从而使其分散在水中而不沉积。