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41.
H. A. S. Schoonbrood M. A. T. Van Den Boom A. L. German J. Hutovic 《Journal of polymer science. Part A, Polymer chemistry》1994,32(12):2311-2325
Simple equations describing monomer partitioning in latices during intervals 2 and 3 in emulsion polymerization with any number of low to moderately water soluble monomers were derived from the extended Morton equation by making various assumptions. It appears that it is mainly the combinatorial entropy of mixing that governs the partitioning behavior, and that other contributions to the free energy of the monomers in the polymer particles are marginal. Experimental results with styrene, methyl methacrylate, and methyl acrylate confirm the validity of the assumptions. In interval 3 of emulsion polymerization the sum of all contributions to the free energy of the monomers in the particles other than the combinatorial entropy of mixing can be taken as a constant that is dependent only on the monomer composition in the particles and independent of the degree of swelling of the particles. The only parameters one needs to know to calculate the monomer concentrations in all phases with help of the derived equations, are the saturation concentrations of each monomer in the polymer particles, and the saturation concentrations of each monomer in the aqueous phase. © 1994 John Wiley & Sons, Inc. 相似文献
42.
微波聚合制备单分散、超细聚甲基丙烯酸甲酯微球 总被引:9,自引:0,他引:9
在微波辐照下,通过甲基丙烯酸甲酯(MMA)的无乳化剂乳液聚合,制备出粒径单分散、超细聚甲基丙烯酸甲酯(PMMA)微球。微波显著缩短聚合诱导期,加快聚合反应,其部分原因是微波加快引发剂过硫酸钾(KPS)的分解。实验证明微波辐照下KPS的表观分解活化能(ED)由128.3kJ/mol降低到106.0kJ/mol。单体浓度是影响PMMA乳液粒子尺寸的主要因素,在[MMA]小于0.3mol/L时,平均粒径随单体浓度提高而线形增加;[MMA]为0.3~1.0mol/L时,平均粒径稳定在约200nm;之后随单体浓度进一步增加,乳液稳定性变差。引发剂浓度增加对平均粒径影响较小,但增大引发剂浓度可显著降低粒径分散度。选取[MMA]为0.23~0.3mol/L、[KPS]为3×10-3~6×10-3mol/L可以得到粒径200nm的单分散微球。以丙酮/水(体积比1/3)为反应介质,可制备出数均粒径45nm的PMMA纳米粒子。在体系中加入3.5×10-3mol/L的Cu2+,可制备出数均粒径67nm、单分散的PMMA纳米粒子。 相似文献
43.
消除夹带溶胀的新液膜操作法曹汉瑾,褚莹,何彦涛,吴子生,严忠(东北师范大学化学系长春130024)关键词液膜,油/水乳液,溶胀,夹带,包裹消除液膜操作中的夹带溶胀对液膜的工业化具有重要意义,夹带溶胀分为包裹溶胀和再液化溶胀。前者是乳状液滴上浮时将水相... 相似文献
44.
Polymer colloids based on 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D ‐glucofuranose (3‐MDG) and butyl acrylate (BA) were prepared via free radical mini‐emulsion polymerization. The kinetic and colloidal features of the copolymerization were investigated. The final particle size (D) of the sugar latexes is inversely proportional to the concentration of the anionic emulsifier (sodium dodecyl sulphate, SDS) and the non‐ionic one (alkyl polyglucoside, APG). It was also found that D is independent of the concentration of either the water‐soluble initiator (potassium persulfate, KPS), or the oil‐soluble initiator (2,2′‐azobisisobutyronitrile, AIBN). The rate of mini‐emulsion polymerization is lower in comparison with the conventional emulsion polymerization under the same conditions. The polymerization rate (Rp) and the total number of particles (Np) are proportional to the 0.72th and 0.93th power of the SDS, and to the 1.40th and 2.22th of the APG concentration. Following reaction orders, 0.79/0.06 were obtained for Rp/Np versus the concentration of KPS, and 0.22/?0.01 for AIBN, respectively. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
45.
P. Hazot J. P. Chapel C. Pichot A. Elaissari T. Delair 《Journal of polymer science. Part A, Polymer chemistry》2002,40(11):1808-1817
Monodisperse, thermosensitive poly(N‐ethyl methacrylamide) microgel particles were prepared by the batch precipitation/emulsion polymerization of water‐soluble N‐ethyl methacrylamide and the hydrophobic crosslinker ethylene glycol dimethacrylate initiated by potassium persulfate. Particular attention was paid to the effect of the crosslinker agent on the polymerization process (kinetics, conversion, and water‐soluble oligomer content). Particles were characterized in terms of their size distribution and swelling capacity. A polymerization mechanism for the water‐soluble monomer and non‐water‐soluble crosslinker is proposed and discussed on the basis of a combination of both emulsion and precipitation polymerization processes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1808–1817, 2002 相似文献
46.
N. SanzJ. Zaccaro L. DelmotteC. Le Luyer A. Ibanez 《Journal of solid state chemistry》2002,165(1):25-34
Organic nanocrystals of N-4-nitrophenyl-l-prolinol (NPP) have been grown in sol-gel matrices prepared from silicon alkoxide precursors. Our process is based on the control of the nucleation and growth kinetics of the dye in the pores of dense gels. Nanocomposites gel-glasses are obtained with a high optical quality due to the small size of the nanocrystals (10-20 nm). Differential scanning calorimetry experiments evidenced clearly the melting point of NPP nanocrystals, which is registered 51°C above that of NPP powder. Micro-Raman and solid state NMR spectroscopies allowed us to demonstrate that our nanocrystallization process does not chemically modify NPP molecules. We specified also the nature of interactions existing between the NPP nanocrystals and the xerogels. These strong interactions, which explain the important increase of the melting point of the nanocrystals in comparison to the NPP powder, are hydrogen bonds between nitro groups of NPP and uncondensed silanol functions of the silicate network. 相似文献
47.
原油乳状液破乳的动态法研究 总被引:5,自引:0,他引:5
The stability of different crude oil emulsions from ASP flooding production well is studied by the method of a stirred tank. The demulsifying of crude-oil emulsion by different demulsifying agents is discussed. The breakage of the crude oil emulsions from the well PO11 by the different types and concentrations of the emulsifying agents is also discussed. The breaking mechanism of the demulsifying agent is described microscopically. 相似文献
48.
49.
研究了MMA-St在氧化还原引发剂KPS-CuSO_4-Na_2SO_3存在下的快速无皂乳液聚合.当[MMA]=0.51mol/L、[St]=0.49 mol/L、70℃对,在[KPS]=2.77×10~(-3)mol/L、[CuSO_4]=1.50×10~(-5)mol/L、[Na_2SO_3]=2.77×10~(-3) mol/L条件下反应100min,转化率大于90%;讨论了胶乳的分子量及其分布;求出了聚合反应活化能E_a=81.6 kJ/mol和聚合反应速率常数k_p=321.9 L/mol·s. 相似文献
50.