苯乙烯/丙烯酸丁酯交联体系乳液聚合动力学研究

以十二烷基苯磺酸钠(SDBS)为乳化剂,过硫酸钾(KPS)引发苯乙烯/丙烯酸丁酯(St/BA)乳液共聚,加入二甲基丙烯酸乙二醇酯(EGDMA)、聚丁二烯生胶(PB)作为交联剂,研究了聚合温度、引发剂浓度、乳化剂浓度、单体配比对聚合速率的影响。实验结果表明,共聚体系的表观活化能为70.67kJ/mol,聚合初始速率与引发剂浓度的0.43次方、乳化剂浓度的0.56次方和单体BA的0.49次方成正比。     

Free radical copolymerization and kinetic treatment of styrene with N-phenylmaleimide

The copolymerization of styrene (M₁) with N-phenylmaleimide (M₂) in chloroform with 2,2′-azobis(isobutyronitrile) as an initiator was investigated. The kinetic parameters, such as reactivity ratios, overall activity energy, and the effect of molar fraction of monomers on the initial copolymerization rate, were determined. The bimolecular termination of the copolymerization was proved. The treatment method proposed by Yoshimura and colleagues was used to estimate quantitatively the contribution of the charge-transfer complex (CTC) and the free monomers in the copolymerization process. The propagation reactivity ratios of CTC and free monomers were calculated by a new method. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1535–1542, 1997     

Modeling of bulk copolymerization reactor using chain-length-dependent rate constants

A mathematical model is developed for a batch reactor in which binary free radical copolymerization occurs. The diffusion-controlled features of the propagation and termination reactions are taken into account by applying the free volume theory, whereas the chain-length-dependent termination rate constant is formulated by using the continuous probability function. Application of the pseudokinetic rate constant method, as well as the terminal model, reduces the complex rate expressions for the copolymerization system to those for the corresponding homopolymerization system. In addition, the moment equations of the living and dead polymer concentrations, as well as the equation for copolymer composition, are derived to compute the average molecular weight and the copolymer composition. The model is proven adequate when applied to the copolymerization system of styrene and acrylonitrile with AIBN(2,2′-azobisisobutyronitrile) initiator. The results of model prediction clearly show that even the propagation reaction is limited by the diffusion of monomers at higher conversion and that the azeotropic fraction of styrene is about 0.6. It is noticed that as the monomer conversion increases, the molecular weight distribution tends to become broader because the weight-average molecular weight increases at a faster rate than the number-average molecular weight. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1015–1027, 1997     

HIPS树脂的合成与表征

采用溶液聚合方法将苯乙烯与聚丁二烯接枝合成HIPS树脂。研究了引发剂种类、溶剂种类和用量对接枝聚合反应和HIPS树脂结构的影响。实验结果表明，三元复合引发剂（AIBN、BPO、DP-275B）的接枝效果最好；以纯的乙苯作为溶剂的体系，相转变过程最长而且相转变后表观粘度随时间上升较慢，而以纯的环已烷作为溶剂的体系，相转变过程最短，相转变后表观粘度随时间上升最快，复合溶剂系随乙苯含量的减少相转变过程逐渐变短、相转变后表现粘度随时间上升变快。环已烷的存在使分子量变小，而分子量分布变宽。     

Effect of the carboxylic acid monomer type on the emulsifier‐free emulsion copolymerization of styrene and butadiene

Carboxylated styrene–butadiene rubber latexes were prepared through the emulsifier‐free emulsion copolymerization of styrene and butadiene with various carboxylic acid monomers. The effects of various carboxylic acid monomers on the particle formation process were investigated. The type of carboxylic acid monomer strongly affected the particle nucleation. The number of particles and thus the polymerization rate increased with the increasing hydrophobicity of the carboxylic acid monomers. There was a significant difference in the polymerization rate per particle. The results showed that particle nucleation and growth were dependent on the hydrophilic nature of the carboxylic acid monomers. The average particle diameter of the carboxylated styrene–butadiene rubber latexes in the dry state was obtained through some calculations using direct measurements of the average particle diameter in the monomer‐swollen state by a dynamic light scattering technique. Several parameters, such as the polymerization rate, number of latex particles per unit of volume of the aqueous phase, and polymerization rate per particle, were calculated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Improvement in physical properties of poly(vinyl chloride) by radiation-induced graft copolymerization with mixed monomers

Gamma-ray-induced graft copolymerization of butadiene with vinyl monomers onto PVC was attempted to improve the physical properties of PVC. The Izod impact strength was increased from 2 kg·cm/cm² to more than 100 kg·cm/cm² by grafting ca. 10% butadiene. But the tensile strength and melt flow were decreased by the grafting. The electron micrograph showed that the mass of polybutadiene in the graft copolymer had a convenient diameter (0.1–1 μ) for absorbing the impact energy. The weatherability of PVC grafted with butadiene was improved by cografting of butadiene with acrylates and methacrylates which had long side chains.     

Zur Radikalischen Copolymerisation ungesättigter Isocyanate mit Vinylchlorid

On the Free Radical Copolymerization of Unsaturated Isocyanates with Vinylchloride The free radical copolymerization of vinyl-, isopropenyl- and p-vinyl-phenylisocyanate with vinylchloride in mass and tetrahydrofurane solution at 50°C is investigated. The incorporation of the isocyanate monomers in the copolymers is favoured. These monomers effect a great decrease of the rate of copolymerization and a crosslinking of the formed homo- and copolymers, whose extent depends on the kind and the quantity of the incorporated monomers. The crosslinking is caused by the forming of isocyanurate units.     

Hydroxyl-terminated cotelomers of butadiene and bromostyrene

The synthesis of hydroxyl-terminated cotelomers of 1,3-butadiene and bromostyrene was studied. Hydrogen peroxide was used in solution copolymerization to obtain cotelomers of average molecular weights of 1000–4000. The higher the hydrogen peroxide concentration, the broader the molecular weight distribution. The molecular weight is apparently unaffected by the hydrogen peroxide concentration within the limits studied. The concentration of bromostyrene in the products is correlated with its concentration in the monomers. Microstructure of the cotelomers is analyzed. Vinyl content is about 25% of the butadiene content. A correlation of the glass transition temperatures of the cotelomers with those of pure polybromostyrene and polybutadiene is discussed.     

The polymerization and copolymerization of nitroalkyl acrylates and nitroalkyl methacrylates

Nitroalkyl acrylates and methacrylates involving some new compounds were prepared. The homopolymerization of these monomers in toluene and their copolymerization with styrene in acetone were carried out with azobisisobutyronitrile as initiator. The rate of polymerization of the nitroalkyl acrylates showed a correlation with the number of nitro groups situated on the ester side chain. The apparent activation energies of the polymerization were found to be 22.0–27.5 kcal./mole for the nitroalkyl acrylates and about 11.5–13.0 kcal./mole for the nitroalkyl methacrylates. From the reactivity ratios and Q-e values of the copolymerization the following information was obtained. The copolymerization behavior of nitroalkyl acrylates and methacrylates showed an alternating tendency, and these monomers belong to the conjugative monomer groups. On the reactivities of these monomers, the polarity of vinyl group was affected a little by nitro group of ester bond side, and the resonance affected little. These monomers were crosslinked with 2-methyl-2-nitro-1,3-propylene diacrylate. Some of the polymers showed marked improvement in the physical properties of elastomers.     

Surface photografting polymerization of vinyl acetate,maleic anhydride,and their charge‐transfer complex. VIII. Charge‐transfer complex (4)

In view of the complexity of surface photografting polymerization of vinyl acetate/maleic anhydride (VAC/MAH) binary monomer systems, a novel method was adopted in the present article to obtain insight into the relevant grafting copolymerization mechanism. This method includes two steps: semibenzopinacol dormant groups were first introduced onto LDPE film by UV‐irradiation and then thermally reactivated to produce LDPE macromolecular free radicals, which initiated the grafting copolymerization of VAC and MAH. It was demonstrated that, in the first step, the solvent used to introduce benzophenone (BP) to LDPE film largely affected the subsequent grafting copolymerization, which was closely related to the affinity of the solvent toward the substrate. The monomer feed composition had considerable influence on both the grafting and nongrafting copolymerization; however, the maximum copolymerization rates did not appear in the polymerization system with [VAC]/[MAH] being 1 : 1, but, in the system with a bit more VAC than MAH, as the total monomer concentration was raised, the maximum copolymerization rates tended to appear in the system with [VAC] equal to [MAH]. The relationship between the total copolymerization rate (RP) and monomer concentration was determined to be LnRP ∝ [VAC + MAH]^1.83. All of these results indicated that both charge transfer (CT) complex formed by VAC and MAH and free monomers took part in grafting copolymerization. This feature differentiated the surface grafting copolymerization of VAC/MAH from the well‐studied thermally induced alternating copolymerization of VAC/MAH. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Free radical copolymerization of methyl methacrylate and allyl acetate Part 2 structure and properties

The structure of the product from the free radical bulk copolymerization of methyl methacrylate (MMA) and allyl acetate (AAc) was investigated. The mole fraction of AAc plays an important role in the copolymerization of these two monomers. Molecular weight (MW) and molecular weight distribution (MWD) are completely altered when the feed composition is dominantly AAc. NMR spectroscopy confirmed the incorporation of AAc into the polymer. However, no allyl–allyl linkages were observed at low conversions. T_g was found to be affected by the incorporation of AAc into the polymer. © 2001 Society of Chemical Industry     

Preparation and polymerization of vinyl monomers containing a heterocyclic pendant group

New vinyl monomers having an isoxazole heterocyclic group were synthesized and were polymerized in dimethylformamide using azobisisobutyro-nitrile as a free radical initiator. The dependence of the rate of polymerization on monomer and initiator concentrations was determined, as well as the activation energy of polymerization. The addition of Lewis acid was found to affect the rate of polymerization. The prepared monomers were copolymerized with styrene, vinyl acetate, acrylonitrile and methyl methacrylate. The monomer re-activity ratios of all the systems were determined by linear and non-linear methods, and the Q and e values for the monomers were calculated by considering the four copolymerization systems in each case. ©1997 SCI     

Synthesis and application of poly(butadiene-g-acrylonitrile–styrene) core–shell rubber particles for use in epoxy resin toughening. I. Synthesis of poly(butadiene-g-acrylonitrile–styrene)

Graft copolymers of acrylonitrile (AN)–styrene (ST) onto polybutadiene were prepared via emulsion polymerization method using a redox initiator system, cumene hydroperoxide–tetrasodium pyrophosphate–ferrous sulfate–dextrose. The effects of initiator, reaction temperature, reaction time, polymer/grafting monomer ratio, and monomer dropping frequency on the graft copolymerization reaction were investigated. Transmission electron micrographs confirmed that the synthesized particles had a core–shell shaped structure. The powdery core–shell shaped poly(butadiene-g-AN–ST) particles with various AN contents in their shells and with different shell thicknesses were prepared, which can be incorporated into brittle epoxy resin as impact modifier. © 1996 John Wiley & Sons, Inc.     

Hydrosoluble copolymers of acrylamide‐(2‐acrylamido‐2‐methylpropanesulfonic acid). Synthesis and characterization by spectroscopy and viscometry

Hydrosoluble copolymers containing sulfonic acid groups incorporated into a macromolecule were synthesized. The group of polymers studied was obtained by free radical solution polymerization, using potassium persulfate as an initiator. The copolymerization of the monomers 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) and acrylamide (AA) was carried out at different pH values of the reaction medium of the monomer mix. The copolymers were characterized by proton nuclear magnetic resonance spectroscopy (¹H NMR) and Fourier transform infrared spectroscopy (FTIR). The viscosity behavior of the copolymers in NaCl solution showed a dependency on the pH of the reaction medium, with higher pH leading to lower viscosities. The acidic conditions of this medium affect the initiator decomposition rate, which is a probable cause of the viscosity variation, and the extent of decomposition increases with increasing pH. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 192–198, 2003     

Self‐driven graft polymerization of vinyl monomers on poultry chicken feathers in the absence of initiator/catalyst

An efficient and simple method for graft copolymerization of powdered chicken feather (CF) with vinyl monomers without any free radical initiator is reported. Various vinyl monomers such as glycidyl methacrylate (GMA), styrene (S), and methyl methacrylate (MMA); (20–60 wt % with respect to CF) were successfully grafted to chicken feather (CF) by using sodium dodecyl sulfate (SDS, 0.086–0.5 mmol) in the absence of any catalyst or initiator. Most likely, the hydrophilicity, hydrophobicity, and complex forming properties of chicken feather keratin with surfactant molecules were responsible for efficient grafting of polymers on CF surface. The effect of polymerization conditions, such as monomer concentration, temperature, and time of reaction, on the grafting parameters such as monomer conversion, grafting efficiency, and molar grafting ratio were studied. The described method showed a good potential of using low cost, easily accessible poultry chicken feathers as grafting material and self catalyzing agent for graft copolymerization with vinyl monomers to produce low cost commodity plastic for various end uses. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44645.     

Die polymerisation der lactame VI. Die copolymerisation von 6-caprolactam und 8-capryllactam

The process of incorporating 6-caprolactam and 8-capryllactam into polymer chains was studied during the hydrolytic, cationic, and anionic copolymerization in the case of equimolar ratio of the above mentioned monomers. At the beginning of the hydrolytic copolymerization at temperatures between 200 and 260°C, 6-caprolactam was more rapidly incorporated into the chains. Decreasing temperature led to a decrease in the total rate of polymerization with increasing difference between rates of incorporating the two components. Contrary to this, at the initial stage of the cationic copolymerization, the incorporation of 8-capryllactam was faster by orders of magnitude than that of 6-caprolactam, the changes of the copolymer composition being independent of temperature. Under the conditions of interest, in the course of the anionic copolymerization the two monomers were characterized with the same rates of incorporation into the polymer chains. Different melting points of products separated at various stages of the copolymerization process corresponded to the above mentioned differences in rates of incorporating individual monomers into polymer chains when different reaction mechanisms were employed.     

丁苯乳液共聚合动力学的研究

本文详细考察了高转化率下各种因素对丁苯乳液共聚合速率的影响。以过硫酸钾为引发剂,岐化松香皂和硬脂酸钾的混合物为乳化剂,正十二硫醇为链转移剂,在5升不锈钢高压釜中进行了丁苯乳液共聚合实验。随着乳化剂和引发剂浓度的增大、乳化剂中硬脂酸钾相对量的增加以及温度的升高,聚合速率均加快;加入少量电解质可以提高聚合速率;加入少量硫醇与完全不加硫醇相比,聚合速率有很大提高。另外,还发现氧对聚合有明显的阻聚作用、水油比对单体转化速率影响不大。同时理论推导了乳胶粒数随时间的变化关系,并在自由基聚合机理,乳胶粒中单体浓度连续下降等假设的基础上推导了高转化率下乳液聚合的数学模型,对于丁二烯、苯乙烯共聚体系,模型计算值与实验值能较好的吻合。     

Diffusion of unreacted monomers detected by ATR FTIR spectroscopy in a photosensitive printing plate after the photoreaction

A water‐developable flexographic printing plate consisting of poly(acrylonitrile‐co‐butadiene), polybutadiene, and carboxylated polyurethane as a polymer matrix, hexanediol dimethacrylate and polybutadiene diacrylate as reactive monomers, and benzildimethylketal as a photoinitiator was prepared and its photoreaction followed by structural change caused by the diffusion of unreacted monomers was characterized. Analysis combined ¹³C‐NMR and attenuated total reflection (ATR) FTIR showed the photoreaction occurred predominantly at the surface of exposure to the light at first, and then the reaction proceeded to the direction of the opposite surface with an increase in the exposure time. Diffusion of unreacted monomers after the photoreaction from the unexposed side to the exposed side was monitored by ATR FTIR. The diffusivity of unreacted monomers was dependent on the extent of photoreaction in the plate and the molecular weight of diffusing monomers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2903–2907, 2004     

Unsaturated polyester resins with different allyl ethers as crosslinking built-in monomers

The effect of the structure of allyl ethers used as built-in monomers of unsaturated polyester resins on the properties of the coatings obtained have been studied. It was found that high hardness of the coatings cured in air using photoinitiators was achieved for the resins with polyfunctional allyl ether monomers incorporated into polyester molecules as the end groups or as the pendant geminal groups. The influence of the presence of a cobalt organic salt on the hardness of the coating from unsaturated resins has also been studied. The extent of crosslinking for the copolymerization of fumaric esters with allyl ethers in air increases, and a smaller amount of photoinitiator may be used when cobalt (II) naphthenate is present in the resin. The results are discussed in terms of the oxidation of allyl ethers and redox cleavage of peroxides formed, leading to an increase in the rate of copolymerization of allyl ethers with fumarate esters. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2031–2039, 1998     

Graft copolymerization of vinyl monomers onto silk fibers initiated by a semiconductor‐based photocatalyst

Graft copolymerization onto silk (Bombyx mori) was carried out with vinyl monomers (methyl methacrylate and acrylamide) and initiated by a semiconductor‐based photocatalyst (cadmium sulfide). The utility of a semiconductor as an initiator in free‐radical photografting and the effects of ethylene glycol and triethylamine with cadmium sulfide on graft copolymerization were explored. Depending on the reaction conditions, 10–48% grafting with methyl methacrylate and 4–26% grafting with acrylamide were achieved. The reaction conditions were optimized, and the grafted fibers were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry analysis, and tensile strength measurements. The chemical resistance and water absorption of the grafted fibers were compared with those ungrafted fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007