Copolymerization of bromophenylmaleimide with ethyl or butyl methacrylate

N‐p‐Bromophenylmaleimide (BrPMI) does not polymerize in solution by conventional free radical mechanism. However, it readily polymerized in bulk when mixed with a free radical initiator and heated in a microwave oven for 7–8 min. Copolymerization of ethyl methacrylate or butyl methacrylate with BrPMI was conducted in dioxane. The copolymers were characterized by IR and ¹H NMR spectroscopy and gel permeation chromatography. The monomer reactivity ratios were calculated by a non‐linear least‐square analysis. Thermal analysis indicated a great improvement in thermal stability of the copolymers compared with the methacrylate homopolymers. BrPMI was also polymerized in bulk in the DSC pan, which allowed the calculation of the activation energy of its polymerization. Copyright © 2003 Society of Chemical Industry     

Preparation of ion‐exchange membranes by hydrolysis of radiation‐grafted polyethylene‐g‐polyacrylamide membranes

Polyethylene‐g‐polyacrylamide membranes were prepared by graft polymerization of acrylamide onto polyethylene films using a preirradiation method. The ion‐exchange membranes were obtained by the hydrolysis of grafted films so as to transform amide groups into carboxyl groups. The fraction of amide groups transformed into carboxyl groups was limited to ～0.5. The characterization and thermal behavior of membranes with different degrees of grafting were evaluated by FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) measurements. The heat of fusion and the crystallinity of polyethylene decreased considerably in the hydrolyzed membranes depending on the degree of grafting. It was found that the grafting of acrylamide led to the reduction in crystallinity due to disruption of the crystallites (crystal defects) and dilution of the inherent crystallinity (dilution effect). The contribution of the hydrolysis step to the crystallinity decrease was negligible. The thermal stability of the membranes as obtained from TGA showed considerable enhancement after hydrolysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 149–154, 2003     

核壳乳液聚合中甲基丙烯酸用量对印花制品的影响

采用核壳乳液聚合法合成涂料印花粘合剂，考察了甲基丙烯酸(MAC)用量的改变对印花产品的牢度和色光的影响：在核中，当MAC的用量分别为0．0g，0．2g，0．4g，0．6g时，干摩牢度分别为25，2．5 ，3,0，3．5，色光由暗变亮；在壳中当MAC的用量分别为0．0g，0.2g，0．4g，0．6g时，干摩牢度分别为2.5，2．5 ，3．0，3．5，色光变亮，对得色量和鲜艳度影响不大。     

Crystallization of Polymer-Derived Silicon Carbonitride at 1873 K under Nitrogen Overpressure

The chemical stability of an amorphous silicon carbonitride ceramic, having the composition 0.57SiC·0.43Si₃N₄·0.49C is studied as a function of nitrogen overpressure at 1873 K. The ceramic suffers a weight loss at p _N2 < 3.5 bar (1 bar = 100 kPa), does not show a weight change from 3.5 to 11 bar, and gains weight above 11 bar. The structure of the ceramic changes with pressure: it is crystalline from 1 to 6 bar, amorphous at ∼10 bar, and is crystalline above ∼10 bar. The weight-loss transition, at 3.5 bar, is in excellent agreement with the prediction from thermodynamic analysis when the activities of carbon, SiC, and Si₃N₄ are set equal to those of the crystalline forms; this implies that the material crystallizes before decomposition. The amorphous to crystalline transition that occurs at ∼10 bar, and which is accompanied by weight gain, is likely to have taken place by a different mechanism. A nucleation and growth reaction with the atmospheric nitrogen is proposed as the likely mechanism. The supersaturation required to nucleate α-Si₃N₄ crystals is calculated to be 30 kJ/mol.     

乙炔黑吸附聚合制导电聚苯胺

用乙炔黑吸附化学聚合新工艺制备导电聚苯胺，可保持电导率不变，但转化率和堆密度提高，并明显改善了聚苯胺的颗粒形态和制膜加工性，使由其制备的聚苯胺复合正极膜和固体聚苯胺锂蓄电池的电化学性能得以改进。     

双环戊二烯聚合反应热力学和动力学研究

研究了ＤＣＰＤ－ＷＯＣｌ４－ＡｌＥｔ３体系前阶段的反应动力学，采用ＧＣ法分析了不同反应条件下的动力学数据，发现ｌｇ（［ＤＣＰＤ］０／［ＤＣＰＤ］）￣ｔ存在线性关系，说明该体系在前段的聚合反应为一链式反应符合二级反应模型。同时还对该体系聚合反应热力学也进行了研究；对聚合反应的ΔＨｐ、ΔＳｐ、ΔＧｐ进行了讨论。     

高分子材料辐射接枝苯乙烯的研究进展

对各高分子材料辐射接枝苯乙烯的动力学，接枝方法及接枝材料的应用进行了综述，讨论限辐射剂量，剂量率，温度，后效应，溶剂，添加剂和高分子材料厚度及结晶性等方面对接枝反应的影响。     

Non-steady-state model for kinetics of free radical polymerization, 4. Direct thermal initiation

This paper deals with the non-steady-state kinetics of direct thermal initiated polymerization. The initiation is assumed to be a bimolecular reaction of the monomer. The relationship between the radical concentration and the monomer conversion is rigorously derived. In further treatment a few very close approximations are introduced based on the fact that the number of monomer molecules reacting in the initiation step is much less than that consumed in the propagation step for a process producing high polymer, and the value of the rate constant for propagation or chain transfer is much lower than that for chain termination. Expressions for various molecular parameters, such as molecular weight distribution, number-average and weight-average degrees of polymerization, and dispersity, are given. Several numerical examples are provided.     

用复合烷基锂引发丁二烯聚合

对以环己烷为溶剂、四氢呋喃为微观结构调节剂、复合烷基锂为引发剂的丁二烯聚合反应过程进行了研究，考察了不同引发温度、不同配比的复合烷基锂对聚合反应的影响，并与以正丁基锂为引发剂的丁二烯聚合反应过程进行了比较。