Monomer Reactivity Ratios for the Copolymerization of p-lsopropylstyrene with Styrene and Methyl Methacrylate

Abstract

The monomer reactivity ratios for the copolymerizations of p-isopropylstyrene with styrene and with methyl methacrylate have been determined by the ionization chamber-vibrating reed electrometer radioactivity assay technique. The values from the differential form of the copolymerization equation are r₁ (styrene) = 1.22, r₂ (p-isopropylstyrene) = 0.89, and r₁ (methyl methacrylate) = 0.44, r₂ (p-isopropylstyrene) = 0.39. The values from the integrated form of the equation are r₁ (styrene) = 1.37 and r₂ = 0.99. These values indicate that, in the copolymerization of p-divinylbenzene (p-DVB) with styrene, the p-isopropylstyrene-like unit, formed from having the first vinyl group of p-DVB reacted, takes part in subsequent propagation reactions with styrene less readily than either styrene or p-DVB.     

Monomer Reactivity Ratios for the Copolymerization of Styrene with Pure Meta-and Pure Para-Divinylbenzenes

Reactivity ratios for the copolymerization of styrene (r ₁) meta-divinylben-zene (r ₂–m) and with para-divinylbenzene (r ₂–p) have been redetermined under different reaction conditions and with different radioactivity assay techniques. The copolymers were prepared at two conversion levels [0.55 to 3.7% and 2.7 to 7.5% and at 80° (rather than 100°)] with benzoyl peroxide (in place of τ-butylhydroperoxide) initiator. The ionization chamber-vibrating reed electrometer radioactivity assay technique developed for other copolymerization studies was used in place of the direct counting technique previously used for the styrene/divinylbenzene systems. The new values are r ₁ = 0.605/r ₂-m = 0.88: r ₁ = 0.77/r ₂-p = 2.08 at 0.55 to 3.7% conversion and r ₁ = 1.27; r ₂–m = 1.08 at 2.7 to 7.5% conversion. These are not in close agreement with previous values partly because of the difference in conditions of copolymerization (temperature, per cent conversion, initiator) and in the improved analytical precision. Also the high-DVB-content (80%) para copolymer data are not assumed to be invalid and are not omitted (as they were before) from selection of the r ₂–p values.     

Reactivity Ratios for Microemulsion Copolymerization of N-butyl Maleimide and Styrene

The oil-in-water microemulsion containing N-butyl maleimide(NBMI, M1) and styrene(St, M2) was prepared. The complexation properties of NBMI and St in microemulsion were investigated by means of 1H-NMR. With the participation of charge-transfer complex(CTC), four reactivity ratios and the relative reactivity of free monomers and CTC were obtained. The result was compared with that measured by Mayo-Lewis method.     

Estimation of Reactivity Ratios in the Copolymerization of Styrene and VeoVa‐10

The styrene and vinyl neodecanoate copolymerization system shows a strong tendency to form two separate homopolymers. In order to improve the feeding strategies and hence the copolymer uniformity, it is necessary to know the reactivity ratios between these monomers. The error‐in‐variables‐method (EVM) is the most recommended mathematical procedure for estimating these parameters. Experiments on free‐radical copolymerization in solution in sealed ampoules are carried out to provide data for the conversion (via gravimetry) and fractional monomer compositions (via Fourier transform mid‐infrared (mid‐FT‐IR) spectroscopy). These data allow estimation of the reactivity ratios. EVM appropriately takes into account the experimental errors in the data and allows determination of the reactivity ratio values by the Mayo–Lewis model (r₁ = 28.60 and r₂ = 1.23). The convergence and robustness of the method decrease considerably with a larger discrepancy between the reactivity values.     

Product Relation of Copolymerization Reactivity Ratios

The copolymerization reactivity ratios designated as r_i = k_ii/k_ij are characteristic of thermodynamic conditions, such as temperature, pressure, and concentration, in which the temperature dependence has been demonstrated by kinetic procedures [14]. It is noted that in radical copolymerization the simple product of the reactivity ratios, e.g., r₁, r₂ generally tends to move toward unity with increasing temperature [2] and that for ionic copolymerization it is usually close to unity [5]. Such an inclination, however, involves some ambiguity in evaluating all the reported data [6] concerning the polymerization conditions.     

The Reactivity Ratios of Acrylonitrile Copolymerization

The reactivity ratios of acrylonitrile copolymerization published from 1971to 1982 are tabulated.     

乙交酯与丙交酯共聚反应和竞聚率的测定

乳酸一羟基乙酸共聚物（PLG）是一种很好的生物医用材料，具有良好的生物相容性和生物降解性，对人体无毒害，可用作医用缝合线[1]、药物缓释胶囊[2]、内固定及牙科材料等[3]．Gilding和Reed[4]在乙交酯和丙交酯共聚反应转化率较高（12．9％～16.4％）时，利用二元共聚方?..     

有电荷转移络合物参与的共聚体系竞聚率

从有电荷转移络合物参与的共聚体系增长基元反应出,提出一种有ＣＴＣ参与的共聚体系竞聚率的求法,从中得到４个竞聚率,自由单体和ＣＴＣ的相对活性等信息。     

丙烯腈和丙烯酸酯基团转移共聚的竞聚率

丙烯腈和丙烯酸酯基团转移共聚的竞聚率邹友思，林国良，戴李宗，兰涛，潘容华（厦门大学化工系，厦门，３６１００５）共聚合中最重要的参数是竞聚率，二元共聚竞聚率对反应机理的研究及生产上的控制均有重要作用。丙烯腈是重要的共聚单体，但它参与的基团转移无规共聚至...     

Reactivity Ratios of Butyl Acrylates in Radical Copolymerization with Methacrylates

The reactivity ratios of four butyl acrylates versus methyl methacrylate and tert-butyl methacrylate were determined for their radical copolymerization in 2-butanone solution using the Jaacks method. The reactivity ratios values obtained were positively verified by substituting into the Alfrey-Goldfinger equation, yielding correct copolymer composition for a series of samples obtained from different initial mole fractions of the comonomers.     

丙烯酰胺与4-乙烯基吡啶共聚合反应竞聚率

测定了丙烯酰胺与4－乙烯基吡啶共聚反应的竞聚率。用紫外分光光度法测定了不同浓度的4－乙烯基吡啶均聚物的吸光度，从而求出在低转化率不同初始单体组成的共聚物中4－乙烯基吡啶含量。用FR和KT两种作图法及YBR计算法对单体的竞聚率进行计算和比较。结果表明：KT法和YBR法计算法较为准确，4－乙烯基吡啶的竞聚率和丙烯酰胺的竞聚率分别为γrVP=0.636,γAM=0.379。     

丙烯腈和甲基丙烯酸酯基团转移共聚的竞聚率

丙烯腈和甲基丙烯酸酯基团转移共聚的竞聚率邹友思，郭金全，兰涛，戴李宗，潘容华（厦门大学化工系，厦门，３６１００５）关键词基团转移共聚．竞聚率．丙烯腈．甲基丙烯酸酯近年来对基团转移共聚竞聚率的研究较活跃［１～３］，一般认为甲基丙烯酸酯和丙烯酸酯两类单体...     

二乙基二烯丙基氯化铵与丙烯酰胺、丙烯酸共聚竞聚率

二乙基二烯丙基氯化铵;丙烯酰胺;丙烯酸;共聚合;竞聚率     

Reactivity Ratios for Microemulsion Copolymeriration of N-butyl Maleimide and Styrene

IntroductionReactivityratioscanofferthemessageofrelativereactivityofcomonomers.TWomonomerreactivityratioscanbeacquiredfromtheend-groupmodelproposedbyMayoandLewis,howevef,thereareonlyapparentreactivityratiosavailablefromthiskineticmodelwhencharge-transfercomplex(CTC)participatesinthecopolymerization.Therefore,thecopolymeriZationinwhichCTCexistsisworthyoffurtherresearch.Sofar,therearethreekineticmodelsofcopolymerizationwiththeparticipationofCTCinall,namely,SeinerandLittmodel',Shirotamodel…     

苯乙烯和丙烯酸丁酯自由基共聚合竞聚率测定与研究

苯乙烯和丙烯酸丁酯自由基共聚合竞聚率测定与研究吴平平，吴玉芳，杨全兴，韩哲文朱清仁（华东理工大学高分子材料研究所，上海，２００２３７）（中国科技大学结构分析开放实验室）关键词苯乙烯，丙烯酸丁酯，竞聚率，序列分布苯乙烯和丙烯酸丁酯是重要的共聚合体系。然...     

甲基丙烯酸缩水甘油酯与甲基丙烯酸甲酯的共聚合及竞聚率测定

以N,N-二甲基甲酰胺(DMF)为溶剂,实施了甲基丙烯酸缩水甘油酯(GMA)与甲基丙烯酸甲酯(MMA)的溶液共聚合,测定了共聚物P(GMA-co-MMA)的红外光谱(FT-IR),对其化学结构进行了表征,并采用差示扫描量热法(DSC)测定了共聚物的玻璃化转变温度(Tg).改变两单体投料比进行共聚合,采用化学分析法测定低转化率下(<7%)共聚物组成,重点研究了两单体的竞聚率.结果表明:GMA与MMA的共聚合易于进行,P(GMA-co-MMA)的玻璃化转变温度(Tg)介于均聚物PGMA(72℃)与PMMA(106℃)之间,当n(GMA)/n(MMA)=4/6时,共聚物的Tg为9l℃.采用FR和KT 2种作图法及YBR计算法对单体的竞聚率进行了计算和比较,结果表明:KT和YBR法较为准确,以DMF为溶剂时,GMA与MMA的竞聚率分别为2.14与0.69.     

A Brief Survey of Methods of Calculating Monomer Reactivity Ratios

Abstract

Various published methods of calculating mocomer reactivity ratio sax surveyed in :he light of computer analysis of a large number of experimental data. One typical system, vinyl chloride-methyl acrylzte, is discussed in detail. Some of the earlier methods, such as the Fineaan-Ross method and the graphicai Mayo-Lewis solution, are considered obsolete. The most preferred method for kinetic interpretations of copolymerization data is indicated.     

红外光谱法测定St—BMA的竞聚率

对于共聚合反应中同一对单体的竞聚率,由于采用的实验方法、计算方法不同,可能有几对、甚至上百对不同的数据。在实际生产中已逐渐趋向于在较高温度下进行共聚合,而文献的竞聚率一般均在较低温度下获得,因此缺乏实用意义。本文用FTIR方法测定苯乙烯(St)-甲基丙烯酸正丁酯(BMA)共聚竞聚率参数r_1和r_2,讨论了温度的影响。     

Free‐Radical Frontal Copolymerization: The Dependence of the Front Velocity on the Monomer Feed Composition and Reactivity Ratios

Frontal copolymerization is a process in which a spatially localized reaction zone propagates into a mixture of two monomers, converting them into a copolymer. In the simplest case of free‐radical copolymerization, a mixture of monomers and initiator is placed into a test tube. Reaction is initiated at one end of the tube, and a self‐sustained thermal wave, in which chemical conversion occurs, develops and propagates through the tube. We develop a mathematical model of the frontal copolymerization process and analytically determine the structure of the polymerization wave, the propagation velocity, maximum temperature, and degree of conversion of the monomers. Specifically, we examine their dependence on reactivity ratios as well as other kinetic parameters, monomer feed composition, and exothermicity of the reactions. Our analytic results are in good quantitative agreement with both direct numerical simulations of the model and experimental data, which are also presented in the paper.

Dependence of front velocity on monomer feed composition for different heat release parameters.     

Analysis of Linear Methods for Determining Copolymerization Reactivity Ratios. III. Linear Graphic Method for Evaluating Data Obtained at High Conversion Levels

If copolymerizations are carried to high conversions, the determination of copolymerization parameters involves significant computational difficulties because the exact integrated form of the copolymerization equation has to be applied. A simple method has been developed to transform experimental data, even at high conversions, to be used in the differential form of copolymerization equation. In this method an average monomer composition is assigned to the corresponding experimental average copolymer composition. The proposed approximation extends the use of our linearization technique previously developed for low conversions. It was established that this method yields highly reliable results for practically.