Polymerization of methyl methacrylate by metallocenes

Attempts at polymerizing methacrylate using metallocenes are reported. Polymerization is successful using ferrocene in a ketone solution, but not in benzene or without a solvent. Ketones are effective in the order: methyl ethyl ketone < cyclohexanone < cycloheptanone. Carbon tetrachloride has an accelerative effect on the polymerization in benzene and methyl ethyl ketone solutions, but no effect in cyclohexanone solution. Some binary systems, which consist of ferrocene and higher valence compounds such as cobalt trisacetylacetonate, are effective redox initiators. Cobaltocene polymerizes methyl methacrylate in the presence of carbon tetrachloride; zirconocene dichloride induces polymerization of methyl methacrylate in a cyclohexanone solution; whereas neither nickelocene nor titanocene dichloride are effective. Styrene and acrylonitrile were not polymerized by the metallocenes examined.     

甲基丙烯酸正丁酯共聚纤维的结构与性能

以甲基丙烯酸β-羟乙酯(HEMA)为第二单体,与甲基丙烯酸正丁酯(BMA)悬浮聚合制得BMA/HEMA二元共聚物,采用冻胶纺丝法制备BMA/HEMA共聚纤维,研究了加入HEMA的对纤维结构与性能的影响。结果表明:随着HEMA含量的增加,BMA/HEMA纤维分子间氢键作用和物理交联作用增强,纤维的玻璃化转变温度升高,但纤维表面变得粗糙,具有疏松多孔结构,其吸附性能提高。当HEMA质量分数为15%时,BMA/HEMA纤维对有机液体三氯乙烯的吸附量达18.5g/g。     

Scaling up the styrene butyl methacrylate copolymerisation reaction

The scale-up of benzoyl peroxide initiated copolymerisation of styrene and butyl methacrylate is studied here. The reaction is carried out in reactors of 3, 10 and 100 1 volume. Increasing the reactor size increase the weight average molecular weight and broadens the molecular weight distribution. Reducing the agitator diameter broadens the molecular weight distribution.     

Polymerization of methyl methacrylate by copper-chelate of polyacrylic hydrazide

Copper-chelate of polyacrylic hydrazide was prepared, and its structure and properties were investigated. It was found that the chelate-polymer initiates radical polymerization of methyl methacrylate in aqueous dioxane at room temperature. The rate of polymerization initiated by the chelate-polymer was much higher than that by monomeric model-chelate of such as acethydrazide. The catalytic activity found in the copper-chelate of polyacrylic hydrazide is perhaps caused by the polyelectrolyte-behaviour of the polymer. The influences of the concentration of copper ion, molecular weight of polymer-ligand, ionic strength, hydrogen ion concentration and composition of solvent on the polymerization were investigated. It was considered that the polymerization is affected not only by stability but also by conformation of the chelate-polymer. The tacticity of the polymethyl methacrylate obtained is also discussed.     

A study of mass transport of linear polystyrene in polyethyl methacrylate gel by dynamic light scattering

Mass [i.e., linear polystyrene (PS) probe] transports in polyethyl methacrylate (PEMA) gels with ethylene dimethacrylate (EDMA) as crosslinker were studied by dynamic light scattering (DLS). For PEMA gels in toluene, we have established that it is a very well matched system, so that it is very convenient to study the mass transport of the PS macromolecule in such a system. Experiments show that the obstruction effects of PEMA gels for the mass transport of PS are obvious. Reasonably, the lower the gel obstruction for mass transport, the higher the diffusion coefficient D_t of PS in gel. Moreover, the larger the molecular weight of PS, the greater the obstruction effect of the gel. Furthermore, we traced quantitatively the evolution of D_t of PS during the crosslinking copolymerization of PEMA. The results show that, after the reaction, the obstacle for mass transport in the gel develops gradually. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2062–2066, 2002     

Reaction catalyzed by montmorillonite: Polymerization of methyl methacrylate

The polymerization of methyl methacrylate (MMA) was carried out in aqueous media having various concentrations of potassium persulfate as initiator in the presence or the absence of montmorillonite (Texas) at various temperatures. The rate of polymerization increased with increasing initiator concentration. Thermal stabilities of the resulting composite materials were studied and the activation energies of polymerization and degradation were determined. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 367–372, 1997     

Semibatch emulsion copolymerization of methyl methacrylate and butyl acrylate

The concentration of sodium lauryl sulfate (SLS) in the initial reactor charge is the most important parameter in determining the particle size of a semibatch emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA). The number of particles formed is proportional to the concentration of SLS to the 0.5–1.2 power and it is proportional to the concentration of the nonyl phenol–40 mol ethylene oxide adduct to the 0.014–0.72 power. The number of particles is almost independent of the concentration of the initiator. The solubility of monomer in water has an important effect on the nucleation mechanism according to the literature. However, the ratio of MMA to BA does not show any significant effect on the latex particle size in our laboratory. The particle size also increases with increasing ionic strength or agitation speed. Experimental data of particle-size distribution and molecular weight distribution support the coagulative nucleation mechanism when the concentration of SLS is way below its critical micelle concentration (CMC). © 1995 John Wiley & Sons, Inc.     

Study of mechanical damage in rubber-toughened poly(methyl methacrylate) by single and multiple scattering of light

As glassy polymers are usually somewhat brittle, several blending techniques are used to toughen these materials and to increase their impact strength. The microstructures of toughened polymers are complicated, as are their mechanical damage mechanisms. Moreover, these materials are mostly opalescent or even opaque, which renders difficult any optical investigation of the damage process. The scale of the damage generally ranges from nanometers to several micrometers, thus requiring a large panel of experimental techniques to investigate its microstructural evolution. When illuminated with a light beam, any non-perfectly transparent body will scatter light with a scattering pattern depending on the size, shape, and location of the microscopic light scatterers it contains. If the body is highly opaque, an incident light beam, if not absorbed, is scattered successively by several scatterers before emerging again at the front surface of the body. It has recently been shown that there is a coherent interference enhancement of the randomly multiple scattered light in a small angle range around the exact reverse direction of the incident light. This so-called coherent backscattering cone can be analyzed in terms of the size, shape and density of the scatterers. In this work, this technique is applied to a rubber-toughened PMMA containing core-shell (hard core) particles, an initially transparent material that becomes progressively opaque during mechanical damage under stress. The damage mechanism within the rubber particles is compared with the size and shape of the light scatterers inferred from coherent backscattering and light transmission measurements.     

Organotin polymers. IV. Binary and ternary copolymerizations of tributyltin acrylate and methacrylate with styrene,allyl methacrylate,butyl methacrylate,butyl acrylate,and acrylonitrile

The monomer reactivity ratios for the copolymerization of tributyltin acrylate with styrene and allyl methacrylate have been found to be r₁ = 0.213, r₂ = 1.910 and r₁ = 0.195, r₂ = 2.257, respectively. Also, the copolymerization parameters of tributyltin methacrylate with styrene and allyl methacrylate were as follows: r₁ = 0.256, r₂ = 1.104 and r₁ = 2.306, r₂ = 1.013. Copolymerization reactions were carried out in solution at 70°C using 1 mole % AIBN, and the copolymer compositions were determined by tin analysis. Ternary copolymerization of the three systems butyl methacrylate–tributyltin methacrylate–acrylonitrile, butyl acrylate–tributyltin methacrylate–acrylonitrile, and styrene–tributyltin acrylate–acrylonitrile have been studied, and the terpolymer composition of each system was determined through tin and nitrogen analyses. The variation of instantaneous and average terpolymer composition with conversion fit satisfactorily the experimental results over a wide range of conversion.     

甲基丙烯酸甲酯与丙烯酸正丁酯乳液聚合的研究

以甲基丙烯酸甲酯与丙烯酸正丁酯为主要原料,过硫酸铵为引发剂,OP-10、十二烷基硫酸钠(K12)为乳化剂,用乳液聚合法合成了聚丙烯酸酯类共聚乳液,考察了聚合条件对乳液聚合的影响。实验结果表明,在单体、引发剂、水用量一定时,合适的反应条件为乳化剂(OP-10∶K12=1∶1)2%,单体滴加时间以60~90min,80℃反应2h左右。     

Preparation and properties of poly(butyl methacrylate/lauryl methacrylate) and its blend fiber

The functionalized copolymers, based on butyl methacrylate (BMA), and lauryl methacrylate (LMA) with crosslinking agent HEMA (hydroxyethyl methacrylate) or DVB (divinyl benzene), have been innovatively synthesized by suspension polymerization for oil absorption. Further, the copolymers and polypropylene (PP) blend fiber were attained via melt spinning. Swelling behaviors were evaluated by equilibrium swelling experiment, oil absorbency test, gel fraction measurement, and optical observations in toluene. The thermal properties and morphologies of the blend fibers were analyzed by thermogravimetry (TGA) and a field-emission scanning electron microscope, respectively. The results show that the copolymers and their blend fibers have an impressive absorbency. PBMA/LMA/HEMA can be up to 35.18?g/g, showing the highest absorption in trichloroethylene. Optical images of swollen polymers in toluene depicted a colloidal translucence with gel structure. Thermogravimetric measurement demonstrates that the copolymer and PP are incompatible and PBMA/LMA/DVB component possesses more thermal stability. The micrographs of the blend fibers exhibit coarse surface and porous cross-section, which leads to the fibers being much more readily wetted by oil and provides a huge space for oil storage.     

丙烯酰胺/甲基丙烯酸丁酯改性纤维素的研究

以纤维素为基体,丙烯酰胺(AM)、甲基丙烯酸丁酯(BMA)为接枝单体,过硫酸钾为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,聚乙烯吡咯烷酮为分散剂,通过悬浮接枝聚合法制备出了纤维素基吸水吸油材料;考察了单体用量、引发剂用量、反应时间、反应温度及交联剂用量等因素对接枝聚合物的吸水、吸油性能的影响。结果表明:在单体与纤维素的质量比为3.0∶1.0,AM∶BMA的质量比为2.0∶1.0,相对于单体,引发剂质量分数为6.0%,交联剂质量分数为0.5%,分散剂质量分数为0.5%,反应温度为70℃,反应时间为4 h的条件下,得到纤维素-AM-BMA接枝共聚物,其吸油倍率为11.55 g/g,吸水倍率为23.51 g/g,聚合度为534.6。     

Soapless emulsion polymerization of butyl methacrylate through microwave heating

Soapless emulsion polymerization of n‐butyl methacrylate (BMA) was carried out through microwave heating with potassium persulfate (KPS) as an initiator at 73 ± 2°C. The influence of the monomer amount, the initiator amount, and the addition of ethanol on the monomer conversion, the particle size, and its distribution were studied. The results indicate that microwave polymerization had a much higher rate and produced smaller particles with a slightly broader size distribution compared with normal polymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2455–2459, 2001     

氯丁橡胶接枝甲基丙烯酸丁酯的热降解动力学

用热重法和微商热重法研究了甲基丙烯酸丁酯与氯丁橡胶的接枝共聚物(CR-g-BMA)的热降解过程。结果表明,该接枝共聚物热降解过程分3个温度范围完成,第1热降解温度为553~653 K;第2热降解温度为653~793 K;第3热降解温度大于793 K,其中第3热降解温度的终止温度明显受升温速率的影响。CR-g-BMA的第1温度范围热分解过程符合Avrami-Erofeev降解机理,即随机成核和随后生成机理,热分解过程平均活化能为234.9 kJ/mol;对于热降解的积分机理函数,其频率因子的自然对数为33.48;对于热降解的微分机理函数,其频率因子的自然对数为48.90。     

Uralkyd and poly (butyl methacrylate) interpenetrating polymer networks

ABSTRACT:: Hydroxyl terminated alkyds synthesized from castor oil, glycerol, and different dibasic acids were used to develop uralkyds and their interpenetrating polymer networks (IPNs) with polybutyl methacrylate (PBMA). Glass transition temperature measurements gave the evidence of interpenetration. The IPNs were characterized for their physicomechanical properties and their phase morphology was studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). As the concentration of the uralkyd in IPNs increases, a gradual increase in elongation, density, and swelling with a consequent decrease in the hardness were observed for all IPNs. Swelling is relatively more prominent in methyl ethyl ketone (MEK) and toluene than in water. From SEM it was observed that IPNs of PBMA‐uralkyd containing phthalic anhydride (UA‐P) as an acid part showed greater compatibility than those containing dimethyl terephthalate (UA‐D). From thermogravimetric analysis (TGA) no significant change was observed in the degradation behavior of the IPNs. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 825–832, 2000     

Polymerization of methyl methacrylate by iron(II) pyridinebisimine complexes

Fe(II) pyridinebisimine complexes activated with trialkylaluminium or modified methylaluminoxane (MMAO) as catalysts were employed for the polymerization of methyl methacrylate. Polymer yields, activities and polymer molecular weights as well as molecular weight distributions can be controlled over a wide range by the variation of the structures of the Fe(II) pyridinebisimine complexes and the reaction parameters such as Al/Fe molar ratio, monomer/catalyst molar ratio, monomer concentration, reaction temperature and time applied to the polymerization of methyl methacrylate. Under optimum condition, the catalytic activity of Fe(II) complex is of up to 74.5 kg_polym/mol_Fe h.     

Polymerization of methyl methacrylate by catalyzed peroxide decomposition without applied heat

The exotherm for the polymerization of methyl methacrylate was monitored by a simple thermal technique to gain useful information about the effect of several factors on the polymerization rate and the degree of completion. All reactions were begun at room temperature (24°C) and no external heating was provided. Initiation was by decomposition of benzoyl peroxide (and mixtures with lauroyl peroxide) catalyzed by the accelerator N,N-dimethyl-p-toluidine. Specific factors examined were peroxide and accelerator levels, sample size, peroxide combinations, and crosslinking agents. The results are discussed in terms of the stoichiometry of the initiator system; the balance of heat generation, heat capacity, and heat loss; and the autoacceleration effect.