Kinetics and modeling of the diffusion‐controlled diallyl terephthalate polymerization

Free radical polymerization kinetics of diallyl terephthalate in bulk was investigated in a wide temperature range from 50°C to 150°C with four different peroxide initiators. Conversion points were measured using Fourier Transform Infrared (FTIR) measurements. The initiator efficiencies and the initiator decomposition rate constants were evaluated from special experiments, applying the theory of dead end polymerization. In addition, the ratios between the degradative and the effective kinetic rate constants to propagation rate constants were obtained from molecular weight measurements at various initiator concentrations. The ratio of chemically controlled termination and propagation rate constant k/k_tc of the polymerization system was obtained using the initial rates of polymerization and the number average molecular weight data between 0.25 · 10^?3 and 15.7 · 10^?3 L mol^?1 s^?1. The glass transition temperature of the polymer, 191°C, was measured by the Alternating Differential Scanning Calorimetry (ADSC) technique. Computed conversions from the developed kinetic model were in good agreement with the conversion and molecular weight measured data. The values of diffusion controlled propagation and termination rate constants k_td0 and k_pd0 with clear and physical meaning were the only two parameters obtained from the developed kinetic model fitting. Polym. Eng. Sci. 44:2005–2018, 2004. © 2004 Society of Plastics Engineers.     

超声辐射丙烯腈的无皂乳液聚合

以过硫酸铵为引发剂,用超声波引发丙烯腈单体进行无皂乳液聚合,研究了单体浓度、引发剂浓度、反应时间对单体转化率的影响情况,并对聚合物进行了IR、TEM表征,结果显示聚丙烯腈乳胶粒尺寸均匀,约为50nm。     

Mechanochemical block copolymerization of poly(vinyl chloride) with methyl methacrylate by ultrasonic irradiation

Summary Mechanical degradation and mechanochemical block copolymerization in systems of poly(vinyl chloride)-methyl methacrylate-solvents have been studied by ultrasonic irradiation at 60°C. The effect of the concentrations of poly(vinyl chloride) on mechanical degradation was investigated. In addition, the effects of poly(vinyl chloride) and methyl methacrylate concentrations on mechanochemical block copolymerization were investigated. The rate equation for mechanochemical block copolymerization has been deduced, and the experimental results were in fairly good agreement with the equation. The changes in the composition of the block copolymer and homopolymers in the reaction products were followed by turbidimetric titration.     

Mechanochemical block copolymerization in heterogeneous systems of the solid polyethylene with acrylamide aqueous solutions by ultrasonic irradiation

Summary Mechanochemical block copolymerization in heterogeneous systems of the solid polyethylene-acrylamide-sodium dodecyl sulfate aqueous solutions has been studied by ultrasonic irradiation at 30 °C. An additional effect of the solid polyethylene and the effects of acrylamide, and sodium dodecyl sulfate concentrations on mechanochemical block copolymerization were investigated. The block copolymerization of acrylamide was initiated by free radical produced from the polyethylene particles by ultrasonic waves. The rate of copolymerization R _p increased with increasing additional amount of polyethylene and that value was of the order of 10^-3 mol/l s. In addition, the R _p was given by R _p [Acrylamide] [Sodium dodecyl sulfate].     

Mechanochemical polymerization of acetylene

Gamma alumina, γ-Al₂O₃, was fractured in an atmosphere of acetylene monomer at room temperature to test whether they would be polymerized by mechanochemistry method on the surface of the alumina. The experimental results were obtained by serveral different methods, including CP–MAS ¹³C-NMR, ESR, pressure drop measurements of the monomer, optical absorption spectroscopy, and solvancy. The results proved the mechanochemical polymerization of acetylene monomer on surfaces of the fractured alumina. Several other combinations of either silica and acetylene monomer or polymers and acetylene monomer were tested for mechanochemical polymerization. This process proceeded with less efficiency in the silica system but no mechanochemical polymerization of acetylene was found in the combinations of the polymers and acetylene monomer.     

Bulk polymerization of methyl methacrylate initiated by high intensity ultrasonic irradiation and ESR study

High‐intensity ultrasound was used to initiate the bulk polymerization of methyl methacrylate. The polymerization rate varied with the sonication time, the intensity of the ultrasound, and the initiator concentration of poly (methyl methacrylate) in the monomer. Electron spin resonance (ESR) spectra, obtained by the spin trapping technique, testified that free radicals were produced during the sonication process, and the concentration of radicals also changed with the sonication condition. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1731–1735, 2002     

Mechanochemical synthesis and characterization of poly(vinyl chloride)-block-poly(ethylene-co-propylene) copolymers by ultrasonic irradiation

Mechanical degradation and mechanochemical reaction in heterogeneous and homogeneous systems of poly(vinyl chloride) and poly(ethylene-co-propylene) polymer have been studied by ultrasonic irradiation at 30 °C. The rates of decrease in the number-average molecular weights of the degraded poly(vinyl chloride) and poly(ethylene-co-propylene) polymer were much faster in order of the solid poly(vinyl chloride)—poly(ethylene-co-propylene) polymer solution, the swelled poly(vinyl chloride)—poly(ethylene-co-propylene) polymer solution, and the homogeneous solution systems. On the other hand, mechanochemical reaction occurred by free radicals produced from the chain scissions of both polymers by ultrasonic waves. The changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(ethylene-co-propylene) polymer in individual reaction systems were obtained. In addition, the microscopic observation of the surfaces of the polymers on before and after mechanochemical reaction is carried out. Received: 10 May 2000/Revised version: 1 August 2000/Accepted: 3 August 2000     

Study on bulk polymerization of methyl methacrylate initiated by low intensity ultrasonic irradiation

Methyl methacrylate (MMA) was polymerized in bulk solutions using low intensity ultrasonic radiation of 0.25 W/cm². The polymerization occurred after 1 h of irradiation time was applied. The polymerization rate was greatly accelerated either by increasing the amount of poly (methyl methacrylate) (PMMA) granular added into the system or by elongating the irradiation time. However, it was found that the reaction rate increased with the decreasing of the ultrasonic frequencies when the exposure time of the polymerization under the irradiation was less than 3 h. Experimental results verified that the polymerization was initiated by free radicals, which were mainly generated from the degradation of PMMA macromolecular chains, the friction between the polymer macromolecular chains and the solvent monomer. These findings were obviously different from those obtained when high intensity ultrasonic irradiation was used. The polymers fabricated in this study by using ultrasound irradiation have a narrower molecular weight distribution compared to those obtained from the polymerizations induced by the conventional initiators. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride) with styrene by ultrasonic irradiation

Summary Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride)-styrene-sodium dodecyl sulfate aqueous solutions has been studied by ultrasonic irradiation at 65 °C. The block copolymerization of styrene was initiated by free radicals produced from the poly(vinyl chloride) particles by ultrasonic waves. The initial rate of the block copolymerization Rp was given by Rp α [Styrene] [Sodium dodecyl sulfate]^1/2. Both copolymer and homopolymer were obtained. For example, when 2.506 g of the poly(vinyl chloride) particles, 24.23 g of styrene, and 54.00 g of sodium dodecyl sulfate aqueous solution (0.500 wt%) were added in the reaction system, the weight proportions of the block copolymer and polystyrene after 60 min were approximately 50 and 20%.     

Mechanochemical synthesis and characterization of poly(vinyl chloride) -block- poly(acrylonitrile-co-butadiene) copolymers by ultrasonic irradiation

Summary Mechanical degradation and mechanochemical reaction in heterogeneous and homogeneous systems of poly(vinyl chloride) and poly(acrylonitrile-co-butadiene) polymer have been studied by ultrasonic irradiation at 30 °C. The rates of decrease in the number-average molecular weights of the degraded poly(vinyl chloride) and poly(acrylonitrile-co-butadiene) polymer in the swelled poly(vinyl chloride) — poly(acrylonitrile-co-butadiene) polymer solution were much faster than the homogeneous solution system and the final average chain lengths led to the smaller values than those in the latter system. On the other hand, mechanochemical reaction occurred by polymer radicals produced from the chain scissions of both polymers by ultrasonic irradiation. The changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(acrylonitrile-co-butadiene) polymer in both reaction systems were obtained. Received: 4 September 2001/Accepted: 22 October 2001     

Mechanochemical synthesis and characterization of poly(vinyl chloride)-block-poly(vinyl alcohol) copolymers by ultrasonic irradiation

Mechanical degradation and mechanochemical reaction in heterogeneous systems of the solid poly(vinyl chloride)-poly(vinyl alcohol) aqueous solutions have been studied by ultrasonic irradiation at 30 °C. The rate of decrease in the viscosity-average degree of polymerization of the degraded poly(vinyl chloride) was much faster than that of the degraded poly(vinyl alcohol). Mechanochemical reaction occurred by free radicals produced from the chain scissions of both polymers by ultrasonic waves. The copolymer was obtained and the molar ratio of the vinyl chloride and the vinyl alcohol units in its copolymer can be determined. In addition, the changes in the composition of the total block copolymer, the unreacted poly(vinyl chloride), and the unreacted poly(vinyl alcohol) were obtained. Received: 1 October 1998/Revised version: 9 January 1999/Accepted: 13 January 1999     

Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride) with styrene by ultrasonic irradiation

Summary The effect of several forms of suspension polymerized poly(vinyl chloride) particles on mechanochemical block copolymerization in the solid poly(vinyl chloride)-styrene-sodium dodecyl sulfate solutions has been studied by ultrasonic irradiation at 60 °C. The block copolymerization of styrene was initiated by free radicals produced from the poly(vinyl chloride) particles by ultrasonic waves. The rates of copolymerization increased with increasing the additional amount of the solid poly(vinyl chloride), the porosity, and the average diameter of the grain particles. In particular, the influence of the average diameter was much larger than that of the porosity. When the porosity and the average diameter were increased, the rates of decrease in the viscosity-average degree of polymerization of the degraded poly(vinyl chloride) were much increased. In addition, the changes in the composition of the block copolymer and homopolymers in the reaction products were obtained.     

全谱直读等离子发射光谱仪(ICP)测定蒸馏水中SiO2含量

实验室用一次蒸馏水质量好坏直接影响化验结果的准确性,特别是对微量元素测定的精密仪器室尤为重要。作为测定微量元素配制标准溶液所用的蒸馏水,S iO2含量是一项重要质量控制指标。根据GB/T 6682分析实验室用水规格标准,采用硅钼蓝分光光度法分析。该方法分析时间长,前处理操作繁琐,所用的试剂多,误差较大。而采用全谱直读等离子发射光谱仪(ICP)进行测定,能克服上述弊端,同时能测定多种金属元素。1 ICP分析原理本方法是利用原子发射光谱源作为等离子体进行测定。试样被激发光源蒸发、气化、离解或分解为原子状态,原子状态进一步电离成…     

Mechanochemical polymerization of styrene initiated by the grinding of quartz

The polymerization of styrene mechanochemically initiated by the wet grinding of quartz was attempted by using a vibrating ball mill with a laboratory scale. The effect of the grinding of quartz on the polymerization of the styrene was investigated by characterizing the polymer formed and the quartz ground. The results showed that styrene could also mechanochemically polymerize by the resulting active species of the grinding of quartz as well as methyl methacrylate. The polymerization was found closely related to the total surface area of the ground quartz. The molecular weight distributions of the polymer formed were not simply unimodal and remarkably broader than those of the methyl methacrylate. It was suggested that the polymerization of the styrene proceeded with a cationic active species from the experimental results and discussions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2849–2855, 2001     

Engineering analysis of crosslinking polymerization of diallyl lsophthalate

A kinetic model for crosslinking free radical polymerization of DAIM (monomer diallyl isophthalate) with initiator CHPC (dicyclohexyl peroxydicarbonate) is developed. An improved version of Batch and Macosko's model was used to describe the initiator efficiency (f) and the active radical fraction (F_act). The experimental data of allyl and carbonyl group consumption are used for the optimization of the model and calculating of f and F_act. From the developed kinetic model and experimental results, obtained by FT‐IR measurements of monomer conversion, the introduction of the F_act was proved. Application of this model may be of use in process modeling of DAIM and other crosslinking polymerizations with CHPC as initiator.     

Gelation in the radical polymerization of dimethyl diallyl ammonium chloride

Within the framework of an irreversible aggregation model on a sample of polydimethyl diallyl ammonium chloride, we demonstrated that gelation occurred on a transient part from the autoacceleration stage until the dopolymerization stage. During part of the autoacceleration, the polymer solution was in a sol state on the segment of autoacceleration. Therefore, the use of the term gel effect in reference to the beginning of the reaction did not seem quite justified. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1394–1396, 2004     

Mechanochemical polymerization of methyl methacrylate initiated by the grinding of inorganic compounds

The polymerization of methyl methacrylate mechanochemically initiated by the grinding of several inorganic compounds was attempted using a vibrating ball mill. The inorganic compounds used were quartz, quartz glass, marble, limestone, feldspar, and talc with the particle size range of 149–210 μm. The results demonstrated that all compounds used in these experiments had the activity for mechanochemical polymerization of methyl methacrylate, and that the degree of the activity at the same grinding time remarkably differed with the kind of compound. The existence of the induction period, which is the time until the polymerization started, was also confirmed in all of the compounds. The molecular weight distributions of the polymer formed were unimodal and somewhat broad in the case of any compound, and the number-average molecular weight was similar to that formed by ordinary radical polymerization. It was suggested that there were two types of the initiation mechanism in the mechanochemical polymerization of methyl methacrylate initiated by the grinding of inorganic compounds. © 1995 John Wiley & Sons, Inc.     

超声辐照法合成水不溶性杀菌剂

以氯球为原料,通过胺化和季铵化两步反应,制得水不溶性杀菌剂.其中季铵化反应在超声辐照下进行,通过正交实验研究了各个反应条件对固载量的影响.研究结果表明:氯代十四烷为树脂质量的4倍,异丙醇为溶剂,异丙醇与氯代十四烷体积比为4:1,反应温度70℃,反应时间6 h,超声输出功率200 W,固载量可达1.088 mmol/g,而无超声处理的反应24 h后,固载量仅为1.037 mmol/g.