Copolymerization propagation kinetics of styrene with alkyl acrylates

Propagation rate constants have been determined at two temperatures (298 K and 323 K) for the copolymerizations of styrene (STY) with methyl acrylate (MA) and STY with n-butyl acrylate (BA) over a range of monomer feed compositions. A pulsed UV laser was used as an initiation source and gel permeation chromatography (GPC) was utilized to analyse the products. None of the copolymerizations conformed to the Mayo-Lewis model, with respect to their propagation rate constants. The results were interpreted on the basis of a penultimate effect on the propagation reaction. In addition, Mark-Houwink constants were determined for poly(MA) and poly(BA) in tetrahydrofuran (THF) at 298 K. These constants are given as [K(dm³ kg^?1),α]: 7·88 × 10^?3, 0·885 and 8·57 × 10³, 0·865 for poly(MA) and poly(BA) respectively.     

Copolymerization of styrene by diphenylzinc-additive systems. Part II: Copolymerization of styrene/1-alkene by Ph2Zn-metallocene-MAO systems

Summary The copolymerization of styrene with 1-alkene (1-hexene, 1-decene and 1-hexadecene) has been tested using combined diphenylzinc-additive initiator systems, including diphenylzinc (Ph₂Zn), a metallocene and methylaluminoxane (MAO). The metallocene were biscyclopentadienyltitanium dichloride, bis(n-butylcyclopentadienyl)titanium dichloride, cyclopentadienyltitanium trichloride and bisindenylzirconium dichloride. For Ph₂Zn-metallocene-MAO systems, titanocenes gave mainly syndiotactic homo polystyrene irrespective of the styrene/1-alkene proportion in the initial feed. Systems including Ind₂ZrCl₂ were able to copolymerize styrene 1-alkene with the copolymers incorporating alkene in a lower proportion than the present in the initial feed. Keywords: Styrene copolymerization; diphenylzinc; metallocene catalysts; tacticity. Received: 17 November 2000/Revised version: 9 May 2001/Accepted: 10 May 2001     

Copolymerization of styrene and methyl methacrylate. Part I: Experimental kinetics and mathematical modeling

A population balance approach is described to follow the time evolution of molecular properties in free-radical copolymerization. The model formulation is based on the two dimensional orthogonal collocation on finite difference (2-OCFD) and method of generating functions (GF) which was properly adopted to calculate time-conversion behavior of styrene-methyl methacrylate copolymerization. A comprehensive model which uses the free volume theory to account for diffusion controlled termination and propagation reactions as well as the variation of the initiator efficiency with respect to the monomer conversion was developed. The model is capable of predicting the conversion, composition and molecular weight development up to limiting conversions. The plasticizing effect of a blowing agent on the rate of copolymerization has been investigated. The phenomenological aspect of rate data is analyzed for the copolymerization of styrene with methyl methacrylate over a full range of conversion and the gel effect index is used to systematize the observations.     

Copolymerization of polyvinylpyridine macromonomers with styrene

Summary Free radical Copolymerization of ( -methylstyryl) poly (2-vinylpyridine) macromonomers with styrene was performed. After separation of residual macromonomer the graft copolymers were submitted to a careful characterization.The copolymers were generally of rather low molecular weight and the average number of grafts per backbone chain was found close to unity. Nevertheless, these polymeric species tend to give aggregates and/or emulsions in selective solvents of the grafts, a typical behaviour of graft copolymers.     

Copolymerization of elemental sulfur with styrene

Copolymerization of elemental sulfur with styrene in the presence and absence of metallic sodium was studied at 120°C and 138°C. Propagation of the reaction was followed by gel permeation chromatography (GPC). Glass transition temperatures of all samples were obtained by differential scanning calorimetry (DSC). Reaction products were fractionated with a preparative-type GPC, and each fraction was characterized by DSC, vapor pressure osmometry, infrared spectrophotometry, and both proton and carbon-13 nuclear magnetic resonance spectrometry. Results indicate that the product is a true copolymer of styrene and sulfur. Kinetics of the copolymerization were studied using GPC to monitor styrene and sulfur concentrations. The initial rate of copolymerization (as followed by the consumption of styrene and sulfur) decreases with increasing initial styrene to sulfur ratio. From kinetic analyses, ratios of the rate constants of homo- and copolymerization were determined. Copolymerization of the reactants is more spontaneous than homopolymerization. The reactivity ratios obtained are 0.2 for styrene and 0.6 for sulfur.     

Copolymerization reactions of butadiene monoxide with 3-glycidyloxypropyltrimethoxysilane and styrene oxide and their glycol derivatives

Copolymerization reactions of butadiene oxide (BuO) with 3-glycidyloxypropyltrimethoxysilane (GPTS) and styrene oxide (SO) were carried out under solvent free condition by potassium hydroxide catalyst. Copolymers obtained from ring opening polymerization of BuO with GPTS and SO were characterized by ¹H-NMR, ¹³C-NMR, FTIR, DSC, and gel permeation chromatography. High-resolution NMR analysis was particularly effective in the study of copolymers microstructures and revealed the structural and sequence details. Block copolymers were formed because of different polymerization velocity of monomers. Average molecular weights of copolymers were between 1500–13 000 Da and polydispersity index of copolymers is rather low (M_w/M_n = 1.17–1.36). Copolymers were hydrolyzed by 1.0 M tetrapropylammonium hydroxide to form copolyglycol having adhesive and fiber characteristics. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47074.     

异戊二烯和苯乙烯阳离子共聚合成研究

采用阳离子聚合法,以异戊二烯、苯乙烯为单体合成了低分子量的共聚物,探讨了催化剂种类、催化剂用量、反应温度、单体浓度、单体配比、反应时间等条件对聚合反应的影响,对合成产物进行了IR及热重分析。研究表明,较佳的聚合条件为,催化剂用量为单体质量的50％、催化剂（AlCl3）与助催化剂（CCl,COOH）=1：1（mol比）、反应温度为20℃、单体用量为溶剂与单体体积的30．8％、异戊二烯：苯乙烯=3：1（体积比）、反应时间为45min,在此工艺条件下,其转化率达100％。     

Copolymerization of styrene. IV. Copolymerization with esters of benzylidenecyanoacetic acid

Styrene was copolymerized in bulk with a number of esters of benzylidenecyanoacetic acid. The kinetic scheme of all pairs fitted the improved scheme of copolymerization, taking into account the effect of the penultimate unit. The Alfrey-Price Q and e values were calculated. Using the modified Taft equation, log (1/r₁) = ρ^*σ^* + δE_s, it was found that the relative reactivities of the ester monomers toward the polystyryl radical were correlated by the polar substituent constants σ^* of the ester alkyl groups (ρ^* = 0.14) and not by their steric substituent constants E_s (δ = 0.008).     

六亚甲基亚氨基锂引发的丁二烯和苯乙烯的共聚合

研究了以六亚甲基亚氨基锂为引发剂,N,N,N’,N’-四甲基乙二胺(TMEDA)为调节剂．环己烷为溶剂的丁二烯和苯乙烯的共聚合。结果表明．随着TMEDA用量的增加,聚合反应速率加快,丁二烯-苯乙烯共聚物的无规化程度提高。在相同的TMEDA用量下,聚合反应速率与用正丁基锂作引发剂时大致相等。     

光活性体N-马来酰基-L-丙氨酸/苯乙烯的合成

以过硫酸钾为引发剂,在微乳液中合成了具有旋光性的N-马来酰基-L-丙氨酸(AMI)与苯乙烯(St)的共聚物。用元素分析法测定了共聚物内氮摩尔分数,从而确定了共聚物摩尔组成与单体配比之间的关系,进而计算出AMI与St的竞聚率分别是0．05,0．10,并计算出相应的AMI单体活性值为1．59、AMI单体极性值为1.50,讨论了共聚物旋光性的成因以及旋光性共聚物的结构。结果表明,该共聚物具有交替共聚合的倾向。     

Copolymerization of sodium styrene sulfonate with sodium chloroacrylate

Summary Sodium styrene sulfonate was copolymerized with sodium chloroacrylate in water-isopropanol mixtures by radical initiation at 70°C. Analysis of the copolymers showed that due to dehalogenation reaction chloroacrylate units underwent various transformations with predominant formation of lactone structures. The copolymer composition was evaluated from NMR spectra. Monomer reactivity ratios were calculated using the integrated copolymerization equation.     

Copolymerization of styrene and methyl methacrylate with nickel acetylacetonate/methylaluminoxane catalyst system

The present work deals with copolymerization of styrene (STY) and methyl methacrylate (MMA) catalysed by nickel acetylacetonate - Ni(acac) ₂ , employing methylaluminoxane (MAO) as cocatalyst. This catalyst system presented low catalyst activities for STY homopolymerization and very high activities for MMA. It seems that the catalyst system based on Ni(acac) ₂ /MAO is effective for the copolymerization of MMA and STY to give block copolymer but it also produced polystyrene and poly(methyl methacrylate) homopolymers. The polymers were characterized by ¹³ C NMR, GPC and FTIR. The polystyrene homopolymer was identified by IR and NMR analyses of the cyclohexane soluble fraction. The presence of absorption bands correspondent to carbonyl group and aromatic ring was observed in the IR spectrum of the acetic acid soluble part. This result is a clue that STY-MMA copolymer with low molecular weight was produced. The high molecular weight copolymer (acetic acid insoluble fraction) was also characterized by IR analysis which indicated the presence of characteristic absorption bands of carbonyl group and aromatic ring. These results were confirmed by ¹³ C NMR analysis. Received: 6 August 1997/Revised version: 29 December 1997/Accepted: 7 January 1998     

Copolymerization of ethylene and styrene with supported TiCl4/NdCl3 catalyst

The copolymerization of ethylene and styrene was carried out in the presence of TiCl₄/NdCl₃/MgCl₂/AlEt₃ catalyst. The influences of comonomer ratio, concentrations of catalyst and AlEt₃, solvents, and temperature on the copolymerization were investigated. Copolymerization products containing styrene of 4–85 mol % were obtained with good yield. The results of ¹³C-NMR, IR, X-ray diffraction, and solvent extraction show that the products are mainly copolymers with various comonomer sequences and exhibit special mechanical properties. © 1994 John Wiley & Sons, Inc.     

Copolymerization of dehydrated castor oil with styrene: Determination of reactivity ratios

Dehydrated castor oil (DCO) has been used as a comonomer with styrene to determine reactivity ratios. The polymerization was a free-radical process in benzene, and the product was isolated by evaporation of the reaction mixture and by two precipitations into petroleum ether from benzene. The copolymer composition was determined by a saponification procedure. DCO was found to have a high chain transfer constant and a very low reactivity ratio (estimated at 0.086) compared to styrene (11.6). It was found that copolymerization is difficult to achieve in a system where the DCO concentration in the reaction mixture was above 20 mole-%.     

氮官能化多锂引发丁二烯/异戊二烯/苯乙烯聚合动力学

以自制氮官能化多锂(以下简称Li)为引发剂,N,N,N′,N′-四甲基乙二胺(TMEDA)为极性调节剂,环己烷为溶剂,对苯乙烯(St)、异戊二烯(Ip)、丁二烯(Bd)进行负离子聚合,合成了星形集成橡胶丁二烯-异戊二烯-苯乙烯三元共聚物(SIBR),研究了不同TMEDA/Li(摩尔比)下SIBR的聚合反应动力学。结果表明,在三元共聚合反应中,3种单体的反应速率与其各自浓度均符合一级动力学关系;在SIBR的合成体系中,随着TMEDA/Li的增大,Bd的反应速率常数先升高后降低,St的反应速率常数逐渐增加,Ip的反应速率常数逐渐降低;当TMEDA/Li为1·0、二乙烯基苯(DVB)/Li(摩尔比)为0·8、引发剂浓度为7·69×10-4mol/L时,单体Bd,Ip,St的表观增长反应活化能分别为31·59,47·64,31·76kJ/mol,链增长频率因子分别为1·02×104,1·09×106,5·27×103min-1。     

Copolymerization of alpha-methyl styrene with butyl acrylate in bulk

The kinetics of the copolymerization of alpha-methyl styrene (AMS) and butyl acrylate (BA) have been studied for the first time. Reactivity ratios for the system have been assessed over a range of temperatures (60-140 °C). Copolymerization models that account for monomer depropagation have been considered in order to determine the importance of depropagation effects for the chosen set of reaction conditions. Full conversion range experiments have been carried out to assess the effects of feed composition, temperature and initiator concentration on polymerization kinetics.     

Copolymerization of unsaturated polyester with styrene in inverted emulsion

Copolymerization of unsaturated polyester with styrene in water-in-oil (W/O) type emulsion was carried out with the use of various basic compounds as emulsifiers. It was found that a stable, gellike W/O type emulsion of unsaturated polyester resin is formed only when pK_a's of the bases are above 6 and their concentrations are higher than some critical value. In these conditions, water can be dispersed in emulsion up to 900% to the resin. By polymerization, the stable W/O type emulsion is transformed to a white solid copolymer which is dry to the touch and which contains 90–95% of initially added water. It was confirmed that the basic compounds react with the carboxylic group of the polyester to form at the water-resin interface polyester salts, which act as true emulsifying agents. The stabilization mechanism of the emulsion at various concentrations of the polyester salt was investigated, mainly by microscopic observations, and an interpretation of the critical value of emulsifier concentration is proposed.     

阻聚剂对酚醛环氧乙烯基酯的贮存及固化影响

通过正交实验法从4种酚醛环氧乙烯基酯树脂(NEVER)阻聚剂:氮杂环、吩噻嗪、对苯二酚、苄基三乙基氯化铵中确定了最佳复配阻聚剂。采用FTIR和DSC研究了含复配阻聚剂NEVER在热贮存下双键的变化及其固化反应动力学,并对固化后产物的不可溶分含量进行了测定。结果表明,最佳复配阻聚剂为氮杂环化合物和吩噻嗪,用量均占树脂质量的0.03%,此时NEVER在80℃下的贮存期可从11 h提高至60 h;树脂经80℃贮存50 h,总的C==C双键保留率达63.7%,说明选定的复配阻聚剂对NEVER具有良好的阻聚作用。固化的表观活化能从79.00 kJ/mol升高至87.44 kJ/mol,复配阻聚剂不影响最终产物的固化完全度。     

Chemical and mechanical properties of vinyl-ester/ABS blends

Various experimental techniques and finite element modelling (FEM) were employed to assess mechanical and chemical properties of vinyl-ester (VE)/poly(acrylonitrile-butadiene-styrene) (ABS) blends with different ABS particle content. The blends were to be used as a toughening agent for interlayer toughened VE/glass composite material. Firstly, the materials' fracture toughness and tensile properties were examined, the results showing excellent toughening potential of the blends as well as a non-linear trend for fracture toughness as a function of ABS weight content. The tensile testing of the blends served to define the yield point of the materials and to obtain their stress-strain curves, which were then used as input into finite element analysis models. The mechanical testing results suggested that a chemical reaction may have occurred between the constituents of the blends. Based on the Raman spectroscopy results and mechanical testing data, 7% of ABS was believed to be the critical ABS content where significant changes in the materials' chemical composition and consequently in mechanical properties occurred. Finally, FEM was undertaken to further verify the existence of this sudden variation in material's properties.