苯乙烯和丙烯酸丁酯微乳液聚合动力学的研究

进行了苯乙烯和丙烯酸丁酯的微乳液聚合,研究了聚合动力学,引发剂种类和浓度、反应温度对反应的影响。     

苯乙烯/丙烯酸丁酯微乳液共聚物链段分布的研究

以苯乙烯/丙烯酸丁酯(St/BA)为共聚单体,进行了微乳液聚合反应,测定了共聚物组成和共聚单体的竞聚率。由竞聚率计算了共聚物分子的链段分布,分析了共聚物分子的微观结构。     

苯乙烯/丙烯酸丁酯微乳液聚合竞聚率及共聚物链段分布的研究

以苯乙烯/丙烯酸丁酯(St/BA)为共聚单体进行了微乳液聚合反应,测定了共聚物组成和共聚单体的竞聚率。由竞聚率计算了共聚物分子的链段分布,分析了共聚物分子的微观结构。     

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.     

Free radical terpolymerization of butyl acrylate/methyl methacrylate and alpha methyl styrene at high temperature

The free radical initiated terpolymerization of butyl acrylate (BA), methyl methacrylate (MMA) and alpha methyl styrene (AMS) has been examined. Kinetic studies focused on elevated reaction temperatures (115 and 140 °C). The studies were made over the full conversion range and examined the effect of reaction temperature, feed composition and initiator level on reaction rates. The composition of terpolymer products and their molecular weights were also analyzed with respect to monomer conversion levels.     

Emulsion-based pressure sensitive adhesives from conjugated linoleic acid/styrene/butyl acrylate terpolymers

Free radical emulsion terpolymerizations of conjugated linoleic acid (CLA), styrene (Sty), and butyl acrylate (BA) were performed at 80 °C. Terpolymers were characterized for composition, conversion, molecular weight and glass transition temperature, latexes were characterized for viscosity and particle size while adhesives were characterized for tack, peel strength, shear strength, storage modulus, loss modulus and tan delta. One impurity commonly found in CLA, oleic acid, was shown to influence the reaction kinetics significantly. Adhesive performance was tuned using divinylbenzene (DVB) crosslinker to keep the terpolymer molecular weight in a desired range. By using a constrained mixture design, the influence of terpolymer composition, chain transfer agent (CTA) concentration, DVB concentration, molecular weights, viscosity and particle size on tack, peel strength and shear strength was investigated. The final forms of the resulting empirical models allowed the creation of 3D response surfaces for pressure sensitive adhesive (PSA) performance optimization.     

Grafting of styrene onto poly(butyl acrylate) in emulsion

The effect of time, temperature, the concentration of initiator and emulsifier, and the ratio of starting polymer to monomer on the degree of conversion (MC) of styrene and the grafting efficiency (GE) of polystyrene has been investigated. The reaction was initiated with potassium persulphate. It has been found that the degree of conversion of styrene and the grafting efficiency change in opposite directions when plotted as functions of the reaction parameters studied. The graft copolymerization is assisted by short reaction times and weight ratios of poly(butyl acrylate) to styrene greater than unity. The results obtained suggest that higher grafting efficiencies are obtained when the concentration of emulsifier is below its c.m.c. (critical micellar concentration) value. When using two different anionic emulsifiers it has been observed that the effect of initiator concentration on the degree of conversion of styrene and the grafting efficiency is complicated. Both the quantities studied (MC and GE) exhibit extrema in the range of initiator concentration studied (3.7?33.3 × 10^?5 mol dm^?3 of H₂O). No meaningful effect of temperature in the range 60°–90°C or that of dodecyl mercaptan (molecular weight regulator) used in an amount 0–0.4% in relation to poly(butyl acrylate) and styrene has been observed on the MC and GE values.     

Inline monitoring of styrene/butyl acrylate miniemulsion polymerization with attenuated total reflectance/Fourier transform infrared spectroscopy

The copolymerization of styrene/butyl acrylate in a miniemulsion was monitored inline with an attenuated total reflectance/Fourier transform infrared (ATR–FTIR) probe. ATR–FTIR spectroscopy was used to track the concentration of the monomers, thereby providing conversion and polymer composition data. Offline gravimetry and ¹H‐NMR spectroscopy were used to provide a comparison with the ATR–FTIR data. Because of inconsistent results with a univariate method, a multivariate or partial least squares calibration method using the full spectra of the reactions was selected and gave excellent results. No statistically significant differences were found between the offline and ATR–FTIR spectroscopy data coupled with multivariate statistics, and this confirmed that ATR–FTIR spectroscopy is a reliable tool for monitoring the conversion and polymer composition in miniemulsion polymerizations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 46–52, 2007     

A kinetic investigation of styrene/butyl acrylate copolymerization

An experimental investigation of the kinetics of the bulk free radical copolymerization of styrene/butyl acrylate initiated with 2,2′-azobisisobutyronitrile (AIBN) was conducted at 50°C using various initiator concentrations and initial monomer ratios including the azeotropic composition. Reactivity ratios were determined by analyzing composition data using the error-in-variables model. The experiments, designed using the Tidwell-Mortimer criterion, were conducted in sealed ampoules at 50°C to low conversion levels (< 7%). From the calculated reactivity ratios, the azeotropic composition was determined and further experiments were run at these conditions as well as at two other initial monomer feed compositions in order to collect composition, rate and molecular weight data. The experiments were run through the full conversion range at two different initiator concentrations.     

High-rate polymerization of acrylonitrile and butyl acrylate based on a concentrated emulsion

A mixture of acrylonitrile and butyl acrylate was polymerized starting from a concentrated emulsion in water. The polymerization was initiated at room temperature by a redox system, consisting of reductants dissolved in the water phase and an oxidant dissolved in the dispersed phase. The initial polymerization was carried out adiabatically with self-heating until a temperature of about 70 °C was reached; this was followed by additional heating in a water bath at a higher temperature, up to a total polymerization time of 30 min. The conversion thus achieved was higher than that obtained via the adiabatic process alone. An optimum temperature during the additional heating was observed. Because of the gel effect, the molecular weight of the product increased with time and the reaction rate became affected by diffusion. The additional heating enhanced the mobility of the species in the system, thus ensuring a final product with a composition near that of the feed.     

Off‐line monitoring of butyl acrylate and vinyl acetate homopolymerization and copolymerization in toluene

A study of butyl acrylate (BA) and vinyl acetate (VAc) solution homopolymerization and copolymerization in toluene was carried out. The conversion and copolymer composition were monitored using traditional techniques (gravimetry and ¹H‐NMR spectroscopy) and attenuated total reflectance‐Fourier transform IR (ATR‐FTIR) spectroscopy with a diamond‐composite probe and light conduit technology. The peak height of the characteristic absorbances of the monomer(s) during the course of the reaction was used to calculate the conversion and copolymer composition for the ATR‐FTIR monitoring. The data obtained using a ReactIR? 1000 reaction analysis system in the off‐line mode showed very good agreement with data obtained using traditional techniques. The solvent effects on BA and VAc solution homopolymerizations and copolymerizations in toluene were also investigated. Improvement to model predictions was obtained by allowing the lumped constant (k_p/k) to vary with the solvent concentration. Experimental data and model predictions of the number‐ and weight‐average molecular weights for the investigated systems are also presented. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2958–2977, 2001     

Role of mixing in copolymerizations of styrene and n-butyl acrylate

The effect of agitation speed and impeller type on the kinetics of emulsion copolymerization of styrene and n-butyl acrylate was investigated. It was shown that the solids content was an important variable in these studies. At low solids (30%), the impeller type and speed did not have any significant effect on the final number of particles and the overall rate of polymerization. Particle size distributions were unimodal in all the cases. At high solids (50%), some differences were observed when 2 different impellers (Rushton and A310 fluidfoil) were used. The polymerization carried out with the Rushton impeller was faster. Bimodal particle size distributions were obtained for both cases; however, the bimodality was more significant when the A310 fluidfoil impeller was used. Greater numbers of particles and unimodal particle size distributions with high rates of polymerization at 30% solids contrasted the lower numbers of particles and bimodal particle size distributions with lower rates of polymerization seen at 50% solids. These differences were attributed to the partitioning behavior of the surfactant (Triton X-405; octylphenoxy polyethoxy ethanol; Union Carbide, Danbury, CT). © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2277–2289, 1998     

建筑涂料用苯丙乳液的研制

以苯乙烯、丙烯酸丁酯和丙烯酸为主要单体,采用种子半连续乳液聚合法合成了苯丙乳液,研究了软硬单体的配比、硬单体中苯乙烯、甲基丙烯酸甲酯的相对量和丙烯酸的用量等对乳液及乳胶漆性能的影响。     

聚(苯乙烯/马来酸酐/丙烯酸丁酯)的合成

以过氧化苯甲酰为引发剂,在甲苯介质中引发聚合制备苯乙烯(St),马来酸酐(MAH)/丙烯酸丁酯(BA)三元聚合物[P(St/MAH/BA)].探讨了反应时间、温度和单体配比等对P(St/MAH,BA)产量的影响,并对P(St,MAH,BA)的结构和性能进行了表征.结果表明,共聚单体质量比对三元聚合物的产率有决定性的作用.当m(St)/m(MAH)/m(BA)为1.00:1.00:0.78时,聚合物的产率最高,达到70%,相对分子质量为3.5×105,且热稳定性良好.     

Design and control of butyl acrylate reactive distillation column system

In this study, the design and control of a reactive distillation column system for the production of butyl acrylate has been investigated. The proposed design is quite simple including only one reactive distillation column and an overhead decanter. The optimal design is selected based on the minimization of total annual cost (TAC) for the overall system. At this optimized flowsheet condition, output multiplicity was found with reboiler duty or feed ratio as the bifurcation parameter. The highest purity stable steady state was selected as the base case condition for the control study. The overall control of this system can be achieved with no on-line composition measurements. Simple single-point tray temperature control loop is designed to infer final product purity. From results of dynamic simulation, the proposed control strategy performs very well in rejecting various disturbances while maintaining butyl acrylate product at high purity. One of the important finding in this paper is that it is better to operate this reactive distillation column not at the exact feed stoichiometric balance point for better operability reason. The control performances of the proposed operating point and the operating condition right at the exact stoichiometric balance point will be compared.     

The influence of copolymerization with methacrylic acid on poly(butyl acrylate) film properties

The effects of methacrylic acid (MAA) on the physical properties of polymer made by emulsion copolymerization of butyl acrylate (BA) and MAA were examined. Emulsion polymerizations were performed with and without MAA and at temperatures of 0.1 and 50 °C, using redox initiation so that the radical flux was essentially independent of temperature. The presence of methacrylic acid had only a small effect on gel fraction and on molecular weight, but a profound effect on the film properties; changing the synthesis temperature was found to slightly alter the properties of the copolymer films. Latexes containing MAA formed much stronger films (from creep tests), and significantly increased tack and peel adhesion. This was attributed to intermolecular dipole-dipole interactions of the acid groups. Conductometric titration measurements revealed that the acid groups were predominantly located inside the latex particles, with only a small proportion in the aqueous phase and on the particle surface. Temperature was found not to affect significantly the partitioning of the acid groups in the latex.     

Infrared process monitoring of conjugated linoleic acid/styrene/butyl acrylate bulk and emulsion terpolymerization

Free radical bulk and emulsion co‐ and terpolymerizations of conjugated linoleic acid (CLA) with styrene (Sty) and butyl acrylate (BA) were performed at 80 °C. The polymerizations were monitored using an attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopic probe. Bulk polymerizations were monitored off‐line while emulsion polymerizations were monitored in‐line. Absorbance peaks related to the monomers and polymer were tracked to provide conversion and polymer composition data using a multivariate calibration method. Off‐line measurements using gravimetry and ¹H‐NMR spectroscopy were compared to the ATR‐FTIR data and no significant differences were detected between the measurement methods. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43574.     

Guest exchange process in syndiotactic polystyrene thin films measured by ATR-FTIR spectroscopy

Guest exchange and desorption processes in syndiotactic polystyrene(sPS)-solvent complex systems (δ form) were studied by means of ATR-FTIR spectroscopy. The intensities of the bands sensitive to the amount of guest molecules and the conformational order of sPS were followed to clarify the mechanism on the guest exchange. Rapid exchange of the guest molecules was observed on the exposure of the δ form sample to toluene and chloroform vapors. The desorption of guest molecules occurs in two stages, which correspond to the rapid desorption mainly from the amorphous region and the slow desorption mainly from the crystalline region, respectively. The diffusion coefficients of the desorbate molecules were evaluated. The time dependence of the intensities of the sPS bands showed that the conformational regularity of sPS changed during the guest exchange process, and the behavior depended on the combination of sorbate and desorbate.     

Agitation effects in the semicontinuous emulsion polymerization of styrene and butyl acrylate

The effect of agitation on the semicontinuous emulsion copolymerization of styrene and butyl acrylate was investigated. Both neat monomer addition and preemulsified feed were used. Experiments with and without a chain‐transfer agent were carried out. For neat monomer addition, a mild degree of agitation (≥ 0.1 kW/m³) was required to avoid monomer mass‐transfer limitations, but even a moderate degree of agitation (0.3 kW/m³) was not enough to overcome the CTA mass‐transfer limitations. Agitation was much less critical when preemulsified feeds were used. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 841–851, 2001     

In situ ATR-FTIR spectroscopy on Ni-P alloy electrodes

In situ ATR-FTIR spectroscopy has been extended to the study of CO and pyridine adsorptions at crystalline and amorphous Ni-P alloy film electrodes, with an emphasis on the alloying effect of P on their adsorption configurations on Ni sites. The Ni-P films were prepared with initial seeding of a catalytic Pd layer on Si, followed by chemical deposition. Transition from bridge-bonded CO (CO_B) dominant to linearly bonded CO (CO_L) dominant adsorption was found with increasing P content, together with a blue-shift in the CO_L vibrational frequency and an attenuation of the Stark tuning rate of CO_L. As for Py on Ni-P electrodes, essentially the N-end-on adsorption was revealed, in contrast to the edge-tilted adsorption on Ni electrode. Modification in the adsorption configurations as compared to that on Ni electrode is ascribed mainly to the site-blocking effect with alloying P, rather than to partial electron transfer between Ni and P.