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有机硅微乳液的研究进展 总被引:8,自引:0,他引:8
近年来大量研究表明,有机硅微乳液与有机硅乳液相比,具有许多优异的性能,如优异的热稳定性、渗透性等。本文主要阐述了有机硅微乳液的形成原理、制备方法及制备过程中的影响因素。在有机硅微乳液的形成原理里,详细介绍了增溶理论和界面张力理论;在有机硅微乳液的制备中,着重讨论了表面活性剂、助表面活性剂、催化剂等对有机硅微乳液形成的影响。 相似文献
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硅氧烷乳液聚合过程中大颗粒形成机理的研究:Ⅱ.聚硅氧烷乳液的耐酸碱… 总被引:5,自引:0,他引:5
研究了阴离子型与阳离子型聚硅氧烷乳液的耐酸碱稳定性,发现阴离子型乳液对酸碱都相当稳定,在乳液制备过程中,酸性催化剂不会引起乳液颗粒的凝聚;而阳离子型乳液的耐酸三稳定性性差,尤其是引起乳液颗粒慢速凝聚的碱浓度下限值很低,碱是制备阳离子型乳液的化剂,碱引起乳液颗粒的慢速凝聚是阳离子型乳液中大颗粒形成的主要原因,在乳液聚合过程中所发生的相当部分的乳化剂从水相向有机硅相的转移也是影响阳离子型乳液稳定性的一 相似文献
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有机硅高分子乳液在工业上有很广泛的应用,例如用作织物处理剂、润滑剂、涂层等。经有机硅高分子乳液处理后的纺织品,可以提高柔软、防皱、防缩、手感等诸方面性能。用机械设备乳化本体聚合的有机硅高聚物制得的乳液往往不够理想;而用乳液聚合方法制备的有机硅乳液,其颗粒小而均匀, 稳定性好, 有利于提高乳液的应用效果 相似文献
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有机硅改性丙烯酸酯共聚乳液合成方法及胶膜性能的研究 总被引:59,自引:0,他引:59
用一次投料法、单体乳液滴加法和引发剂滴加法有机硅改性丙烯酸酯共聚乳液,聚合过程、胶粒形态及乳液稳定性的观测结果表明:单体乳液滴加法是合成该类乳液的最佳方法,研究了单体乳液滴加法中有机硅含量与聚合反及胶膜性能的关系,结果表明:有机硅含量在15%以下时,聚合反应可以顺利进行,胶膜性能不仅依赖于聚合时有机硅单体的总量,而且还依赖于有机硅单体中活性硅氧烷所占的比例。 相似文献
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八甲基环四硅氧烷阴离子乳液聚合反应的研究 总被引:2,自引:0,他引:2
研究了八甲基环四硅氧烷(D_4)在十二烷基本磺酸(DBSA)及其钠盐(Na-DBSA)作用下的阴离子乳液聚合反应,讨论了温度、乳化剂和催化剂用量对反应速度及聚合物分子量的影响。认为该聚合反应包括D_4的水解开环、D_4和羟基硅氧烷的加成及羟基硅氧烷之间的缩合三类基本反应,乳液颗粒表面是主要反应区。 相似文献
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This work focused on the anionic polymerization of octamethylcyclotetrasiloxane (D4, D = Me2SiO2/2) initiated by a new kind of initiator hexamethyldisilazyl-lithium (MMNLi). 29Si-NMR spectroscopy and gas chromatography (GC) were used to characterize the polymerization products. The process was accelerated by adding a small amount of high activity monomer D3 and by raising the polymerization temperature. At the end of polymerization more than 95% of the monomer was converted to polymer and only a very small amount ofD4 and D5 remained in the polymers. 相似文献
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四氢呋喃开环聚合的研究——Ⅲ.本体聚合的总生长反应速度常数 总被引:1,自引:0,他引:1
用溴丙烯-高氯酸银或癸二酰氯-高氯酸银引发四氢呋喃在0℃进行本体聚合,测得总生长反应速度常数(k_p)分别为0.32×10~(-3)及0.38×10~(-3)升·克分子~(-1)·秒~(-1)。这样低的k_p值认为是由于ClO_4~-抗衡负离子具有强的亲核性所致。在溴丙烯-高氯酸银催化体系配此中加大银盐用量(到过量51%),引发诱导时间缩短,聚合速度加快,而k_p值的增大不明显。 相似文献
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研究探讨了己内酰胺和八甲基环四硅氧烷两种完全不同的环单体的共聚过程。在反应初期,环硅氧烷快于己内酰胺而先聚合,随后己内酰胺很快达高转化率。随聚合反应时间延长和环硅氧烷单体配比的增加,共聚体中的硅氧烷含量都相应增加。研究提出并证实了聚合过程中的一些主要反应,并由此推断了共聚产物的结构表达式。 相似文献
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J. D. Petke Gerald M. Maggiora Lester L. Shipman† Ralph E. Christoffersen 《Photochemistry and photobiology》1980,32(5):661-667
Ab initio configuration interaction wavefunctions and energies are reported for 16 doublet states of the anion radical of ethyl bacteriopheophorbide a (Et-BPheo a-˙), and are employed in an analysis of the electronic absorption spectrum. The lowest excited doublet state D1 is predicted to lie 8601 cm-1 above the ground state D0; the D1← D0 transition is nearly forbidden, with a computed oscillator strength f= 0.002. The visible absorption spectrum is shown to consist of transitions to three 2(π, π*) states, D2, D3, and D4. The D4← D0 transition (y-polarized, f= 0.91) appears to account for observed intense absorption at 15 800 cm-1. The Soret band of Et-BPheo a-˙ is shown to consist of transitions to several 2(π,π*) states, D7-D15. Transitions of particularly high intensity include D7← D0 (y-polarized, f= 0.72), D10← D0 (y-polarized, f= 1.1), D12← D0 (xy-polarized, f= 0.86) and D15← D0 (y-polarized, f= 0.83). Spin density data and plots are used to describe and compare the general features of the unpaired spin distributions in D0 and D1, which are in reasonable agreement with other reported calculated values and available experimental data for D0. 相似文献
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A novel highly active catalyst of TiCl_4/MgCl_2--Al(C_2H_5), system (called SN-1 catalyst, in whichrare earth compound NdCl_3, is included) was used for studying stereospecific polymerization of styrenein benzene solution. Highly isotactic polystyrene was prepared with far better yield and higher cataly-tic efficiency than the results ever reported in literatures. The influences of concentration of mono-mer, catalyst, triethyaluminum as well as polymerization temperature on the catalytic efficiency, yield,tacticity and molecular weight of polystytene have been investigated. 相似文献
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In this paper, the stereoselective homogeneous catalysis polymerization of phenylacetylene by using two kinds of catalysts W(CO)_5CH_3I and W(CO)_4I_2 produced from UV laser photolysis of W (CO)_6 in CH_3I, I_2—C_6H_6 and CHI_3—C_6H_6 respectively was studied. The effects of laser energy, laser irradiation time and lifetime of catalyst on the polymerization of phenylacetylene were discussed. The photoproducts of W (CO)_6 in CH_3I, I2—C_6H_6 and CHI_3—C_6I_6 were determined by IR spectra. The structures of polyphenylacetylene obtained by W (CO)_5CH_3I and W (CO)_4I_2 catalysts were characterized by IR spectra and ~1H NMR spectra. 相似文献
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The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by " cage " vanadyl polycarboxylate (P=VO)-thiourea (TU) complex was investigated. The overall rate ofpolymerization isThe relationship between the induction period (τ) and the temperature of polymerization as well as the concentrations of reactants can be expressed as follows :The molecular weight of polyacrylonitrile increases with increasing monomer concentration and decreases with increasing temperature of polymerization and concentrations of vanadyl polycarboxylate and thioureaThe polymerization mechanism was proposed and discussed. 相似文献