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1.
Graft polymerization of methyl methacrylate onto acacia gum has been studied in detail. The grafting was found to be optimal under the following reaction conditions: gum at 0.4 g/dL, monomer at 7.52 × 10?;2 mol/dL, ceric ammonium sulfate at 15.81 × 10?;4 mol/dL, H2SO4 at 0.037 mol/dL, temperature at 50 °C and time at 3.0 h. Fourier transform infrared spectroscopy was sed for the confirmation of grafting. Thermal and physical properties of the copolymer were studied. A probable mechanism of polymerization has been suggested based on reaction kinetics. 相似文献
2.
Free radicals induce two principal types of interaction between fluoro-ketones and olefins, both of which lead to polymeric products. Copolym-erization of the fluoroketone through its carbonyl group leads to poly-ethers. Hydrogen abstraction, presumed to be largely intramolecular, also occurs to give highly branched polymers with fluoroalcohol groups at terminal positions on the branches. 相似文献
3.
两种磁性复合微球的制备及其性能对比 总被引:1,自引:1,他引:1
为了得到蛋白吸附性能良好的免疫磁性载体,文章用反相微乳的方法合成了壳聚糖磁性复合微球(Chitosanmagneticcompositemicrospheres简称CMCM),与常用的单体聚合法制备的聚苯乙烯磁性复合微球(Polystyrenemagneticcompositemicrospheres,简称PMCM)从粒径和表观形貌、微球铁含量、磁响应性、表面官能基团等性质做了对比表征,结果表明,CMCM是一种比PMCM更理想的免疫磁性微球载体材料。 相似文献
4.
C. G. Overberger Naoki Yamamoto 《Journal of polymer science. Part A, Polymer chemistry》1966,4(12):3101-3114
Copolymers of styrene and methyl methacrylate prepared with lithium dispersion as initiator do not contain random sequences of both monomers. Fractionation of the copolymers with acetonitrile and the NMR spectra of the insoluble fractions show that these are block copolymers which consist of a polystyrene portion and a poly(methyl methacrylate) portion. When the copolymerization is stopped at low conversion the copolymer has a high styrene content, which sometimes exceeds the value expected for radical copolymerization. This fact would indicate that styrene is preferentially polymerized at the early stages of chain propagation. When the copolymerization is carried to high conversion some crosslinked polymer is formed which contains more styrene than the soluble part of the same experiment. When a piece of metallic lithium is used as initiator, it is found that the crosslinked polymer is formed on the surface of the metal. The addition of lithium phenoxide or β-naphthoxide to the system eliminates the formation of crosslinked polymer. A possible mechanism is proposed. 相似文献
5.
Reactivity ratios and full conversion range data (conversion, copolymer composition, molecular weight averages, glass transition temperature) are presented for styrene (STY)/methyl methacrylate (MMA)/copolymerization at elevated temperatures (130 and 150°C), a region where polymerization studies are scarce for the system, both for purely thermal polymerization and for peroxide‐initiated ones. 相似文献
6.
苯乙烯-甲基丙烯酸甲酯嵌段共聚物的合成与表征 总被引:2,自引:0,他引:2
采用阴离子聚合技术合成了一系列苯乙烯-甲基丙烯酸甲酯的两嵌段共聚物(PS-b-PMMA).采用GPC、FTIR、NMR(1HNMR、13CNMR和固体NMR)和DMA等手段进行了表征.结果表明,所得产物为高分子量、窄分布、具有微相分离结构的两嵌段共聚物. 相似文献
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8.
梳型接枝共聚物的合成(IV)-氯乙酸降冰片烯甲酯引发苯乙烯、甲基丙烯酸甲酯原子转移自由基聚合的研究 总被引:3,自引:0,他引:3
首次报道以自制氯乙酸降冰片烯甲酯(NMCA)为引发剂的苯乙烯、甲基丙烯酸 甲酯的原子转移自由基(ATRP)本体聚合。详细考察了单体转化与反应时间、产物 分子量及分子量分布间的关系。研究发现,此引发引发甲基丙烯酸甲酯ATRP反应所 得聚合物的分子量分布较宽(PDI = 1.80~2.45),且实测值(GPC)与理论值偏差 较大。而NMCA引发的苯乙烯的ATRP反应可得分子量分布较窄(PDI = 1.54)、实验 值(GPC)与理论值基本吻合的产物。单体转化率随反应时间的变化及产物分子量 随单体转化率变化研究证明这一聚合反应具有活性聚合反应特征。产物的NMR分析 证明所合成产物分子中降冰片烯环上双键未参与聚合反应。 相似文献
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10.
Lifen Zhang Jie Miao Zhenping Cheng Xiulin Zhu 《Macromolecular rapid communications》2010,31(3):275-280
Initiators for continuous activator regeneration in atom transfer radical polymerization (ICAR ATRP) is a new technique for conducting ATRP. ICAR ATRP has many strong advantages over normal ATRP, such as forming the reductive transition metal species in situ using oxidatively stable transition metal species and a lower amount of metal catalyst in comparison with the normal ATRP system. In this work, the iron‐mediated ICAR ATRP of styrene and methyl methacrylate are reported for the first time using oxidatively stable FeCl3 · 6H2O as the catalyst in the absence of any thermal radical initiator. The kinetics of the polymerizations and effect of different polymerization conditions are studied. It is found that the polymerization of styrene can be conducted well even if the amount of iron(III ) is as low as 50 ppm.
11.
The cathode-initiated copolymerization of styrene and methyl methacrylate (MMA) in dimethylformamide yielded a copolymer which was found to be a mixture of the high and low molecular weight copolymers. The composition of the former, rich in MMA, was similar to that of a typical anionic copolymer. The latter, of anomalously high styrene content, was assumed to be produced on the cathodic surface via an anionic process, where styrene monomer was preferentially adsorbed. This was confirmed by capacitance measurement of the electrode and sequence analysis of the copolymer. 相似文献
12.
R. Kh. Yumagulova S. V. Kolesov Yu. B. Monakov 《Russian Journal of Applied Chemistry》2005,78(2):291-294
The effect of ferrocene and zirconocene dichloride on the rate and constants of copolymerization of methyl methacrylate with styrene was studied. The results obtained suggest that the metallocenes in the elementary steps of the reaction.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 297–300.Original Russian Text Copyright © 2005 by Yumagulova, Kolesov, Monakov. 相似文献
13.
D. F. Grishin N. B. Valetova L. L. Semenycheva I. S. Il'ichev 《Russian Journal of Applied Chemistry》2005,78(8):1325-1328
The effect of (allylbenzene)tricarbonylchromium on the kinetic parameters of radical polymerization of methyl methacrylate and styrene and on the molecular-weight characteristics of the resulting polymers was studied. 相似文献
14.
甲基丙烯酸甲酯、苯乙烯与顺丁烯二酸二丁基锡三元共聚物的合成与表征 总被引:1,自引:0,他引:1
以过氧化苯甲酰(BPO)为引发剂,将顺丁烯二酸二丁基锡(DBTM)与苯乙烯(St)、甲基丙烯酸甲酯(MMA)进行本体三元共聚反应,探讨了共聚反应条件.用液相色谱、红外光谱、核磁共振氢谱和热重分析对共聚物的结构和性能进行了表征.动态热流变性实验结果表明,在含锡量相同的情况下,共聚物对PVC的热稳定效果优于DBTM,可以作为多功能化的PVC热稳定剂. 相似文献
15.
Flash pyrolysis of the copolymers acrylonitrile-methyl methacrylate and acrylonitrile-styrene has been carried out over the whole range of compositions, and yields of the monomers have been measured. In the first case, all of the methyl methacrylate is recovered as monomer except when a unit is isolated between two acrylonitrile segments. However, the yield in acrylonitrile monomer is lower; it corresponds to the units isolated between long sequences of methyl methacrylate plus the isolated acrylonitrile diads. The agreement between the calculated and experimental yields is excellent only if one takes into account the penultimate effects. In the second case, however, it is not possible to deduce a quantitative interpretation of the yields of either styrene or acrylonitrile monomers. 相似文献
16.
Abstract The monomer reactivity ratios for the copolymerizations of p-isopropylstyrene with styrene and with methyl methacrylate have been determined by the ionization chamber-vibrating reed electrometer radioactivity assay technique. The values from the differential form of the copolymerization equation are r1 (styrene) = 1.22, r2 (p-isopropylstyrene) = 0.89, and r1 (methyl methacrylate) = 0.44, r2 (p-isopropylstyrene) = 0.39. The values from the integrated form of the equation are r1 (styrene) = 1.37 and r2 = 0.99. These values indicate that, in the copolymerization of p-divinylbenzene (p-DVB) with styrene, the p-isopropylstyrene-like unit, formed from having the first vinyl group of p-DVB reacted, takes part in subsequent propagation reactions with styrene less readily than either styrene or p-DVB. 相似文献
17.
《液相色谱法及相关技术杂志》2012,35(3):323-336
Abstract Silica gel and a mixture of chloroform and ethanol were used as the stationary and the mobile phases, respectively. At the isocratic elution mode, the copolymers tended to adsorb on the column with increasing MMA content in the copolymers, with increasing column temperature, and with decreasing ethanol content in the mobile phase. The copolymers appeared always at the position proportional to the interstitial volume in the column, otherwise they adsorbed on the column. The equilibrium distribution of the copolymers between the mobile phase and the stationary phase cannot be considered in this system. Hydrogen bonding of carbonyl groups in MMA units of the copolymers to silanol groups on the surface of silica gel was considered to be the main interaction between the copolymers and the adsorbent. The hydrogen bonding increases with increasing the number of carbonyl groups per unit surface of copolymer coil in solution and with increasing free silanol groups on the silica surface. Ethanol in the stationary phase controls the content of the free silanol groups on the surface and is controlled by the content of ethanol in the mobile phase in addition to column temperature. This phenomena can be explained by introducing the term of the adsorption energy of a copolymer segment with the silica surface. The adsorption energy is proportional to the strength of the hydrogen bonding. Above the critical adsorption energy which is defined to be equal to the dissolution energy of the copolymer to the mobile pahse, the copolymers adsorb on the surface of silica gel and the desorption of the copolymers advances when the adsorption energy approaches to the critical adsorption energy. No adsorption of the copolymers is possible when the adsorption energy is equal or below the critical adsorption energy. 相似文献
18.
High temperature starved feed semibatch solution polymerization is used to produce acrylic resins for automotive coatings. These operating conditions promote secondary reactions that have a strong impact on polymerization rate and polymer molecular weight (MW). This study experimentally investigates high temperature semibatch copolymerization of butyl methacrylate and styrene, a system subject to the combined effect of depropagation and penultimate propagation kinetics. A mechanistic model including these complexities is constructed in Predic®. With the termination rate coefficient fit to the semibatch results and all other coefficients taken from independent experiments, the model provides good predictions of monomer conversion and MW. Various representations of copolymer termination kinetics from the literature are compared to the values fit from experiment. 相似文献
19.
Summary: High temperature semibatch free radical copolymerizations of dodecyl methacrylate (DMA) and styrene (ST) were carried out. A mechanistic model including depropagation and penultimate chain growth was built in Predici®. The comparison between the simulated and the experimental final polymer molecular weights indicates that the initiator efficiency decreases when DMA is used as a comonomer. Using estimated initiator efficiencies and termination coefficients, the model provides good fits to the complete set of experimental data. 相似文献
20.
Heiner Stange Michael Ishaque Norbert Niessner Michel Pepers Andreas Greiner 《Macromolecular rapid communications》2006,27(2):156-161
Summary: Radical homopolymerizations and copolymerizations of styrene were performed in toluene and N,N‐dimethylformamide (DMF) as solvents using different initiators with and without microwave irradiation. Only the homopolymerization of styrene under microwave irradiation in DMF with DtBP showed significantly enhanced styrene conversion whereas other initiators resulted in no or only slight increase of styrene conversion under microwave irradiation. In any case, DMF was required to gain in styrene conversion under microwave irradiation. Significantly higher monomer conversions were observed under otherwise comparable conditions in the copolymerization of styrene and methyl methacrylate (MMA) in DMF. Microwave‐induced selectivity of monomers was not observed in copolymerizations.