RADIATION CROSSLINKING OF BRANCHED POLY (VINYL ACETATE)

In the present work, radiation crosslinking of different branched poly (vinyl acetate) have beemstudied and the validity of the relationship between sol fraction and radiation dose: R(S+S~(1/2)=1/U_(1qo)+p′_o/q_oR~βto branched poly(vinyl acetate) have been assured.     

富勒烯化聚环氧丙基咔唑的合成与表征

通过Ｆｒｉｅｄｅｌ－Ｃｒｒａｆｔｓ反应制备了富勒烯化的聚环氧丙基咔唑，聚合物中Ｃ６０的含量最高可达７．６ｗｔ％。通过凝胶渗透色谱法测定了聚合物分子量，并采用＾上Ｈ和＾１３Ｃ－ＮＭＲ，ＩＲ，热分析及光谱等手段对其结构进行了分析与表征。     

CALCULATING THE MOLECULAR INTERNAL ROTATING STERIC FACTOR OF POLYMERS BY THE RADIATION CROSSLINKING METHOD

In this paper, calculating the molecular internal rotating steric factor of polymers by the radiation crosslinking method is studied and a relationship between the molecular internal rotating steric factor (σ) and crosslinking parameter βis established~([1]) by taking account of the effect of polymer chain flexibility on βvalue, σvalue of polymer obtained by this method is in agreement with that given with other method.     

CHARACTERIZATION OF RADIATION GRAFT COPOLYMER OF INORGANIC COMPOUND ONTO ALKENE

ＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＲＡＤＩＡＴＩＯＮＧＲＡＦＴＣＯＰＯＬＹＭＥＲＯＦＩＮＯＲＧＡＮＩＣＣＯＭＰＯＵＮＤＯＮＴＯＡＬＫＥＮＥＺｈａｎｇＷａｎｘｉ；ＣｈｅＪｉｔａｉ；ＹａｎＭｅｉｌａｎ（ＣｈａｎｇｃｈｕｎｉｎｓｔｉｔｕｔｅｏｆＡｐｐｌｉ...     

STRUCTURE EFFECTS ON THE SOL FRACTION-DOSE RELATIONSHIP IN RADIATION CROSSLINKING OF POLYMERS

The structure effects of polymers on the relationship between sol fraction and radiation dose arediscussed in detail. In consideration of the deviation of experimental results from Charlesby-Pin-ner's and Chen-Liu-Tang's expressions relating sol fraction to radiation dose, we introduced an ex-ponent βconcerned with the structure and property parameters of a polymer (glass transition tem-perature T_g and molecular internal rotating steric factor δ) and assumed that the fracture density isproportional to R~β(R is radiation dose). Thus, a general expression, formula (9), relating solfraction to radiation dose is derived. When β=1 andβ=0.5, this expression is reduced to the above-said two expressions. Us-ing this general expression, the experimental data of a number of polymers are treated. It is shownthat the expression is in good agreement with the experimental results, βvalue is in the range of 0. 5 to1.0.     

交联聚丙烯酰胺吸水凝胶的强度

高吸水材料是一类新型的功能高分子材料,已有广泛开发和应用。本文讨论了含大量无机填料膨润土的阴离子型交联聚丙烯酰胺(JSWAM)吸水凝胶的强度及其形态结构。 吸水材料JSWAM的制备:将填料搅拌分散于丙烯酰胺水溶液中,同时加入规定量的甲叉基双丙烯酰胺、过硫酸铵、碱,而后聚合并水解。将聚合物胶块造粒、烘干、粉碎。凝胶强度     

表面增强拉曼光谱研究吸附态的变化

测量了吡啶分子在电化学处理的银表面和亚甲基蓝分子在硝酸刻蚀银表面的表面增强拉曼光谱（ＳＥＲＳ）．对ＳＥＲＳ谱线的分析结果表明，吡啶分子在较低的表面吸附分子密度时倾向于平躺方式；而在较高的表面分子密度时，则倾向于向垂直吸附态转化．亚甲基蓝分子在较低浓度时主要是平躺吸附，随Ｃｌ－浓度的增加，亚甲基蓝从“平躺”吸附态转向“站立”吸附态．     

Study on Adsorption States by Surface-Enhanced Raman Spectroscopy

Abstract

SERS has been used as a state-resolving probe to study the adsorption states. in the case of pyridine (Py) adsorbed on the Ag electrode surface, the equilibrium and transition between two adsorbed states, i.e., the perpendicular mode adsorbed through the nitrogen lone-pair electrons and the flat mode through the π electrons of the aromatic ring, were studied. It was found that in the low pyridine concentration or the initial stage of adsorption, the flat mode was favored. While the concentration became higher and the adsorption tended to equilibrium, the adsorbed molecules would transit to the perpendicular mode. The similar phenomenon was also observed when changing the applied electric potential and the pH value of the solution. In the case of the adsorption of Methylene Blue (MB) on the HNO₃-etched silver surface, the influence of Cl^? ions on the adsorption states of MB was investigated. It showed that MB molecules adsorbed on the silver surface tended to transform from the “lying-down” state to the “end-on” state while adding Cl^? ions.     

Structure and Dynamics of Confined Polymer Melts from Attractive Interaction to Repulsive Interaction Between Polymer and Smooth Wall

We studied the static and dynamic properties of unentangled polymer chains which have a variable strength of interaction with the confining smooth walls by means of the lattice Monte Carlo simulation based on the bond-fluctuation model, that is, investigated the wall-polymer interactions which systematically vary from attraction to repulsion. A critical value of attractive potential(ε_wc) is found to be -0.6k_BT, and only below it can the adsorption layer of monomers be formed near the wall. At the critical point of attraction ε_wc, attractive interaction counterba- lances the wall-polymer excluded volume effect, which minimizes the confinement effects on both chain dimension and mobility. Influences on both chain dimension and mobility increase with the increasing of either attraction or repulsion imposed by the walls. Despite of the nature and strength of the wall-polymer interaction, with the decrease of film thickness, configurations more parallelly aligned and flattened are adopted by confined chains, and a systematic trend of deceleration is found. Variations of chain dynamics with both film thickness and wall-polymer interaction can be well explained by the corresponding changes in the confinement of the nearest-neighboring particles that surround the chains. Besides, the thickness of the interfacial layer inside polymer films, where chains adopt a flattened “pancake” shape, is about two times the bulk radius of gyration and independent of the wall-polymer interaction.     

有限变形下单晶变温本构模型

本文构造了单晶热弹粘塑性的本构模型,模拟材料在不同温度下的力学行为。该模型以晶体热运动学作为分析变形的基础,即考虑温度变化情况下总体变形梯度的乘式分解,建立温度影响下的以弹性变形梯度为基本变量的控制方程来描述单晶材料的变形,算法采用隐式积分方法来求解控制方程以保证计算的稳定性。模型能反映单晶材料变形过程中温度对应力-应变响应的影响。