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利用Ca(OH)2和H3PO4中和反应制备悬浮聚合分散剂超细羟基磷酸钙(HAP). 通过正交实验法,研究了反应温度、Ca(OH)2浓度、H3PO4滴加速度、表面活性剂十二烷基苯磺酸钠(SDBS)的加入量等各因素对反应产物羟基磷酸钙结晶形态与尺寸的影响. 分别将不同条件下制备的HAP与聚乙烯醇(PVA)组成复合分散体系,通过甲基丙烯酸甲酯(MMA)的悬浮聚合反应,比较了各组的聚合效果. 应用红外光谱及透射电镜对HAP进行了表征,分析了HAP的结晶形态及尺寸对聚甲基丙烯酸甲酯(PMMA)的粒径及其分布的影响. 结果表明,本实验制备的长′宽为140 nm×35 nm的针状结晶HAP与PVA的复合分散体系对MMA悬浮聚合效果最好,可制备出综合性能较好、粒径d32达1.41 mm的PMMA光学小球. 相似文献
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本文以苯酚和甲醛为反应单体,采用聚乙烯醇(PVA1788)作分散剂,三乙胺(TEA)作碱催化剂,六次甲基四胺(HMTA)作交联剂,利用水相悬浮缩聚法制备了球形酚醛树脂。在稳定悬浮缩聚体系引入致孔剂,制备多孔的酚醛树脂微球,并对木质素部分替代苯酚制备多孔酚醛树脂微球进行初步探讨。通过实验确定了水相悬浮缩聚法制备酚醛树脂珠体基本合成工艺:先将苯酚、甲醛、三乙胺加入到一定浓度的PVA水溶液,在95~97℃反应40 min后,加入HMTA,继续反应4 h,再用1 mol/L的盐酸溶液调节pH值至2,固化反应1 h,可得到形态规整的珠体;并发现PVA浓度对酚醛树脂珠体粒度影响很大,粒度分布较宽。甲苯致孔得到多孔球形酚醛树脂微球,粒径分布较无致孔剂时窄,孔径在2μ以上;甲苯用量5 g,PVA浓度为0.375%时,得到的粒径在20~80目间的粒子数量达90%;提高甲苯量能增大多孔球形酚醛树脂微球比表面积,但加宽粒径分布;且高甲苯添加量时,PVA浓度对缩聚产物形态影响非常显著,低PVA浓度下易结块,高PVA浓度下得细粉(粒径小于200目)。邻苯二甲酸二丁酯致孔得到外表面光滑内表面多孔的酚醛树脂中空微球,粒径分布也窄,粒径在20~80目间粒子数量占80%以上。木质素替代苯酚制备多孔球形酚醛树脂,木质素能参与反应成球,但球形度稍差,孔径也更小。 相似文献
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针对聚酰胺微胶囊的制备,设计制作了简易微通道,以对苯二甲酰氯和1,6-己二胺、二乙烯三胺为壁材,吐温80为表面活性剂,聚乙烯醇(PVA)为保护胶体,采用界面聚合法制备出单分散(分散系数<5%)聚酰胺微胶囊。所制备的聚酰胺微胶囊的分散系数ε在0.2%~0.5%范围内,且具有良好的球形度。对影响聚酰胺微胶囊粒径和分布的因素进行了研究,结果表明:随着吐温80和聚乙烯醇用量的增加,连续相流量增大和分散相流量的减小,聚酰胺微胶囊粒径减小、分布变窄。 相似文献
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悬浮聚合用HAP/SDBS无机分散体系的作用机理 总被引:5,自引:0,他引:5
研究了HAP粉末的沉降特性与生成过程,考察了HAP粉末和不同表面活性剂配合在苯乙烯单体分散液中的吸附特性,同时研究了HAP粉末复合不同表面活性剂的无机分散体系用于苯乙烯单体悬浮聚合时的聚合稳定性。对HAP/SDBS无机分散体系用于悬浮聚合时的分散作用机理进行了探讨。简化了用于苯乙烯悬浮聚合用HAP的制备方法:取消缓冲体系,缩短陈化时间,室温制备。且制备的分散剂用于聚合时为常量的1/5。 相似文献
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针对传统悬浮聚合制备聚苯乙烯颗粒粒径分布宽、有效粒子收率低的问题,采用过硫酸铵/磷酸钙复合分散剂体系,在无外加表面活性剂情况进行苯乙烯悬浮聚合,制备了聚苯乙烯珠粒。通过对聚合稳定性、聚苯乙烯珠粒粒径及分布的测定与分析,考察了磷酸钙、过硫酸铵的用量及比例对悬浮聚合的影响,并分析了过硫酸胺对悬浮聚合的分散稳定机理。结果表明,当过硫酸铵和磷酸钙的用量分别为单体质量的0.01%和1.00%时,悬浮聚合体系稳定,得到的粒子透明性好,平均粒径为1.35 mm,粒径分布窄;通过改变过硫酸铵和磷酸钙的用量,可以调节聚苯乙烯珠粒的平均粒径。 相似文献
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以过硫酸钾为引发剂,十二烷基硫酸钠为乳化剂,叔十二烷基硫醇为链转移剂,通过乳液法对溴化苯乙烯、苯乙烯、丙烯腈进行共聚得到溴化苯乙烯-丙烯腈共聚物.考察了引发剂、乳化剂、链转移剂的添加量,反应温度,反应时间,水和单体比例等对聚合反应收率的影响.研究表明:较适宜的反应条件为反应温度80℃,反应时间6h,水与单体质量比4∶1,引发剂质量为单体总质量的0.4%,乳化剂质量为单体总质量的4%,叔十二烷基硫醇为单体总物质的量的2%;上述条件下的产物收率高,相对分子质量4万左右,热分解温度高于350℃. 相似文献
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The crosslinked spherical phenolic beads (PB) were prepared with phenol and formaldehyde in alkaline medium by suspension polymerization technique. Poly(vinyl alcohol) (PVA) hexamethylenetetramine (HMTA), and triethylamine (TEA) were used as stabilizer, crosslinking agent, and basic catalyst respectively. The resulting PB with higher yield (82.5%) and relatively uniform particle size range (0.2–1.8 mm) were formed at 95–97°C, 550 rpm for 4 h, by using varied amounts of PVA as a stabilizer. The particle size and its distribution could be adjusted by selecting a suitable polymerization medium, consisting of monomer added to water, and by varying their relative amounts, mechanical agitation and stabilizer concentration. The yield % of PB was also varied with the concentration of stabilizer, agitation rate, and monomer‐to‐water ratio. The effects of concentration of the stabilizer, agitation rates, and monomer‐to‐water ratio on PB formation and morphology are described. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2323–2330, 2006 相似文献
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采用经Hummers法制成的改性石墨(MG)为阻燃成分,让其与经聚乙烯醇改性的脲醛树脂(MUF)进行原位插层聚合,得到的MG-MUF作为可发性聚苯乙烯(EPS)的包覆阻燃剂。选用最佳预发泡工艺处理的EPS珠粒为芯材,包覆剂在一定含量的复合型固化剂作用下与EPS珠粒共混,经热蒸汽膨胀模压成型。对包覆样板进行阻燃性能、保温性能和力学性能测试。结果表明,阻燃剂MG含量为20 %、包覆比为3:1的样板的极限氧指数为30.5 %,而其水平燃烧等级达HF1级,综合性能较好。 相似文献
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以聚乙烯醇接枝玉米淀粉为主剂的API胶粘剂 总被引:12,自引:2,他引:10
介绍了一种不含甲醛的聚乙烯醇接枝玉米淀粉胶粘剂的合成方法,探讨了改性机理,对聚乙烯醇与玉米淀粉的配比、次氯酸钠的用量、过硫酸钾的用量等影响胶粘剂性能的因素,以及主剂与交联剂PAPI的配比进行了讨论,该胶粘剂可代替脲醛树脂作为木材、胶合板用胶粘剂。 相似文献
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反相悬浮聚合法制备超强吸水树脂 总被引:3,自引:0,他引:3
以环己烷作为分散介质,以司班80作为分散荆,N,N-亚甲基双丙烯酰胺和多元醇作为交联剂,过硫酸铵作为引发剂采用反相悬浮聚合法分两阶段合成了核壳型超强吸水树脂,得到的产品呈颗粒状,吸去离子水倍率为998g/g,吸生理盐水的吸液倍率达到147g/g。探讨了分散荆、交联剂、反应温度、丙烯酸中和度及核壳比对超强吸水树脂物理状态及吸液能力的影响。 相似文献
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Molecularly imprinted polymer beads of bovine serum albumin (BSA) were prepared via inverse phase suspension polymerization, using BSA as the template molecule, a combination of acrylamide and methacrylic acid (MAA) as double functional monomers, and N, N′‐methylene bisacrylamide as the crosslinker. The effect of different monomer ratios and degrees of crosslinking were investigated. When both selectivity and physical properties of the resultant polymer beads were taken into account, the ratio of MAA in the total monomers was chosen at 40% (m/m) and the degree of crosslinking at 30% (n/n), the resultant polymer beads had good selectivity (α = 2.77) and good physical properties. The effects of pH and temperature were studied. It turned out that the functionalization of polymers of BSA prepared via inverse‐phase suspension polymerization exhibited specific recognition for BSA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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High-molecular weight (HMW) poly(vinyl alcohol) (PVA) was prepared via an emulsifier-free emulsion polymerization of vinyl acetate (VAc) using a redox initiation system in low temperatures, and the subsequent saponification with potassium hydroxide in methanol. The effect of the polymerization conditions on the conversion, molecular weight, and branching degree was investigated. PVA with maximum viscosity-average degree of polymerization (DP) of 8270 could be prepared by saponification of poly(vinyl acetate) (PVAc), with DP of 10,660 obtained at temperature of 10°C, monomer concentration of 30%, potassium persulfate molar ratio to monomer of 1/2000, agitation speed of 160 rpm. The conversion was above 90%. From the emulsifier-free emulsion polymerization of VAc in low temperature, PVAc with HMW and high linearity was effectively prepared, which might be useful for the preparation of high-strength and high-modulus PVA fiber. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献