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通过采取定期取样的办法,利用紫外分光光度仪测得不同时间下的同一时刻的丙烯酰胺的转化率和光引发剂2-羟基-2-甲基-1-[4-(2-羟基乙氧基)苯基]-1-丙酮在混合物中的含量,可以发现丙烯酰胺的光聚合过程存在明显的3个阶段,根据同一时刻下丙烯酰胺的转化率对应的引发剂的含量,建立以光引发剂消耗量划分聚合过程的三阶段模型,将聚合过程分为聚合前期、聚合中期和聚合后期,通过光照强度、狭缝宽度和旋转速度研究了光引发剂的分解动力学,计算出不同条件下的引发剂的分解速率常数kd.结果表明,实验条件下光引发剂分解速率常数kd在4.00×10~(-4)s~(-1)内可调控,在聚合三阶段模型中存在最佳kd组合,即第一阶段kd为4.00×10~(-4)s~(-1),第二阶段kd为1.90×10~(-4)s~(-1),第三阶段kd为1.90×10~(-4)s~(-1),得到合成聚丙烯酰胺(PAM)的最佳自由基浓度是10.82×10~(-8)~12.56×10~(-8)mol·L~(-1)s~(-1),光引发剂的初始浓度[I]0应控制在100~110 mg/L. 相似文献
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采用丙烯酸,2-丙烯酰胺-2-甲基丙磺酸为功能单体,N,N’-亚甲基双丙烯酰胺为交联剂,正十二醇、1,4-丁二醇及二甲基亚砜为致孔剂,偶氮二异丁腈为引发剂在原位聚合,制备出了以丙烯酰胺类强阳离子交换整体柱为核心的电渗泵.在乙腈-磷酸盐二元流动相体系下,考察了驱动电压,有机调节剂,盐浓度,pH对该泵流量的影响.流量与驱动... 相似文献
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为改善梳形聚醚-聚甲基丙烯酸甲氧基多缩乙二醇酯[P(CH_1=C(CH_3)CO(OCH_2CH_2)_nOCH_3),n=8,22,分子量分别为400,1000,简称PMEO_8,PMEO2_(22)的力学性能,作者曾用等离子体引发聚合代替自由基引发聚合制备了PMEO_8,PMEO_(22)及其与丙烯酰胺(AM),甲基丙烯酰胺(MA)的共聚物,取得了较满意的结果。为系统地研究 相似文献
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以咪唑、丙烯腈和溴辛烷等为原料,合成了新型阳离子型可聚合离子液体表面活性剂单体:氯化-1-正辛基-3-(4-丙烯酸丁酯基)咪唑(PMOIH8)。 以2-氯丙酰胺为引发剂,Cu0粉/三-(2-二甲氨基乙基)-Me-6-TREN为催化体系,采用单电子转移活性自由基聚合法对丙烯酰胺(AM)、PMOIH8进行了二元共聚合反应,合成了一种新型阳离子共聚丙烯酰胺/丙烯酸酯P(AM/PMOIH)。 FT-IR、MS和1H NMR分析表明,所得聚合物为目标产物,采用GPC测得聚合物的相对分子质量为2×103~14×103,相对分子质量分布Mw/Mn在1.21~1.75之间。 考察了催化剂、引发剂等因素对聚合的影响。 结果表明,降低催化剂用量,聚合反应速率变慢,链增长速率常数kappp由0.0168 min-1降低至0.0065 min-1,Mw/Mn由1.25~1.71增加至1.32~1.75,引发效率Ieff=90.24%;增加引发剂用量,Mw/Mn由1.25~1.71减小至1.21~1.68,kappp由0.0168 min-1增加至0.0201 min-1,Ieff增加至93.17%。 相似文献
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I. V. Andreeva V. N. Artemyeva V. V. Nesterov N. V. Kukarkina 《Journal of polymer science. Part A, Polymer chemistry》1979,17(11):3415-3424
Two methods for the polymerization of acrolein are proposed: suspension polymerization in water with the redox system K2S2O8:AgNO3 = 1:0.1 with respect to the monomer and a static method with the system K2S2O8:PA–SO2 adduct. The dependencies of yield, molecular weight, and structure of polyacrolein under investigation on the following factors: the amount and the ratio of the initiator components, the pH of the medium, and the monomer:solvent ratio were investigated. The structure of polyacrolein was studied by infrared spectroscopy, thermogravimetric analysis, and chemical functional analysis. The molecular weight distribution of samples of static and suspension polyacroleins modified under identical conditions was determined by gel permeation chromatography. 相似文献
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Intermolecular association of some polystyrene and poly(methyl methacrylate) (PMMA) samples bearing sulphate and/or sulphonate end-groups prepared by using the redox initiator systems K2S2O8 + NaHSO3, Na2SO3 + Cu2+, NaHSO3 + O2 has been studied for dilute solutions in toluene, chloroform, o-dichlorobenzene, tetrahydrofuran (THF) and ethyl acetate respectively by viscometry and in toluene and THF by osmometry. Significant association of the polymers occurs in toluene, chloroform and o-dichlorobenzene in the dilute solutions used in this work. However, association is significantly reduced in chloroform containing 2% ethanol or in toluene containing 2% methanol. Tetrahydrofuran appears to be the preferred solvent for determining the molecular weights of such polymers, since association is insignificant in this solvent. 相似文献
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V. N. Krasil’nikov 《Russian Journal of Inorganic Chemistry》2007,52(2):258-262
Phase ratios in the three-component oxide system K2O-V2O4-SO3 in the region of the sulfur trioxide concentrations corresponding to its concentrations in the active component of vanadium catalysts for SO2 to SO3 conversion have been studied using powder X-ray diffraction, IR spectroscopy, microscopy, and chemical analysis. Four individual compounds (K2VO(SO4)2, K2(VO)2(SO4)3, K2VO(SO4)2S2O7, and K2(VO)2(SO4)2S2O7) and K2(VO)2(SO4)2S2O7 and VOSO4-base solid solutions of composition K2(VO)2+x (SO4)2+x S2O7 (0 ≤ x ≤ 1.5) were found in the system. K2VO(SO4)S2O7 and K2(VO)2(SO4)2S2O7 lose their sulfur trioxide when heated above 350°C under an inert atmosphere, and convert to K2VO(SO4)2 and K2(VO)2(SO4)3, respectively. This implies that K2VO(SO4)2S2O7 and K2(VO)2(SO4)2S2O7, as well as K2(VO)2+x (SO4)2+x S2O7 solid solution, cannot exist in the active component of real industrial catalysts. 相似文献
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A. S. Badran A. B. Moustafa A. A. Yehia S. M. M. Shendy 《Journal of polymer science. Part A, Polymer chemistry》1990,28(2):411-424
The emulsion polymerization of vinyl acetate using potassium persulfate and cyclohexanone sodium bisulfite as redox pair initiation system was studied. The rate of polymerization, maximum conversion, and the number of polymer particles produced were found to change with redox initiator, monomer and emulsifier concentrations, and temperature variation. The rate of polymerization was found to be dependent on the initiator, the monomer, and the emulsifier concentrations to the 0.88, 0.22, and 0.20 powers, respectively. The K2S2O8–NaHSO3 redox system was found to decrease maximum conversion and doesn't form a stable emulsion. The apparent arrhenius activation energy (Ea) estimated for the polymerization system was 65.6 kJ/mol. The viscosity average molecular weights for some obtained poly(vinyl acetate) were determined. 相似文献
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《Polyhedron》1986,5(10):1531-1536
The reactions of the sulphite radical anion, SO−3, which was generated either from a Ce4+-NaHSO3 system at pH 2.5 or from a Ti3+ (ethylenediaminetetraacetic acid)-H2O2-Na2SO3 system at pH 9 in aqueous solutions, with some olefinic compounds were investigated by use of a rapid-mixing flow technique coupled with ESR which can detect the radicals having a lifetime of 5-100 ms. The SO−3 radical could add to the CO double bond in the olefinic compounds in both acidic and alkaline aqueous solutions, although the SO−3 radical is more active in acidic conditions than in alkaline conditions. From the observed hyperfine splitting constants of the SO−3 adducts of the olefinic compounds, the preferred conformation of the adducts was discussed. 相似文献
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(2-甲基丙烯酰氧乙基)三甲基氯化铵-丙烯酰胺反相微乳液共聚合研究 总被引:14,自引:0,他引:14
采用SPAN-OP复合乳化剂和K_2S_2O_8-Na_2SO_3氧化还原引发剂,进行(2-甲基丙烯酰氧乙基)三甲基氯化铵-丙烯酰胺的反相微乳液共聚合。测得单体的竞聚率r_(DM·MC)=1.11±0.16,r_(AM)=0.53±0.08。在单体总浓度为20—40%(wt),引发剂浓度为0.01—0.05%,乳化剂浓度为10—18%,聚合温度为299K的条件下,得到共聚反应动力学方程:R_p=k[M]~(1.07)[I]~(0.52)[E]~(0.90),文中对上述结果做了解释。 相似文献
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Various crown ethers were used as phase-transfer catalysts for free radical polymerizations of some water-insoluble vinyl monomers such as acrylonitrile, methylmethacrylate and styrene with persulfate as initiator. The catalytic abilities of these crown ethers for free radical polymerization of acrylonitrile with S2O82?ion as an initiator were in the order: 18-crown-6 > 15-crown-4 > 12-crown-4 > benzo-15-crown-5 > dibenzo-18-crown-6. Among various persulfates such as Na2S2O8 K2S2O8 and (NH4)2S2O8, ammonium persulfate was the optimum initiator for the polymerization of acrylonitrile catalyzed by 18-crown-6 or 15-crown-5. Among the organic solvents used, chloroform seems to be the best solvent for the catalytic polymerization of acrylonitrile. An apparent activation energy of 72.9 kJ mol?1 was observed for the polymerization of acrylonitrile. The catalytic reaction rates of free radical polymerization for these hydrophobic vinyl monomers were in the order: acrylonitrile > methylmethacrylate > styrene > isoprene. Effects of concentrations of crown ether, initiator, and nitrogen on the polymerization of these vinyl monomers were investigated. 相似文献
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Abstract The kinetics of phase-transfer-agent-assisted free-radical polymerization of methyl methacrylate using K2S2O8 as the water-soluble initiator and triethylbenzylammonium chloride (TEBA) as the phase-transfer catalyst (PTC) was investigated in toluene-water biphase media at 60°C. The effect of varying [MMA], [K2S2O8], [TEBA], [H+], the ionic strength of the medium, and the temperature on the rate of polymerization (R p) was studied. R p was found to be proportional to [MMA]2, [K2S2O8]1, and [TEBA]0.5. Based on the kinetic results, a mechanism involving initiation of polymerization by phase-transferred S2O8 2- and termination by Q+ (quaternary ammonium ion) is proposed. 相似文献
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A. Gopalan S. Paulrajan N. R. Subbaratnam K. Venkata Rao 《Journal of polymer science. Part A, Polymer chemistry》1985,23(7):1861-1868
Polymerization of the symmetrical nonconjugated diolefin, N,N′-methylene bisacrylamide, was carried out using peroxodisulphate ion -Fe2+ as redox initiator. The rate of polymerization is found to depend on [M]3/2 and [S2O82?]1/2 and independent of [Fe2+] over a range. A polymerization mechanism involving cyclopolymerization in the propagation step is suggested. Evidence in favor of the cyclopolymerization mechanism is discussed. Evaluation of the rate parameters indicates that the deactivation of the primary radical SO4? by Fe2+ ion is a factor to be reckoned with. 相似文献