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偏氯乙烯/丙烯腈/苯乙烯悬浮共聚合动力学 总被引:1,自引:0,他引:1
本文研究了偏氯乙烯(VDC)/丙烯腈(AN)/苯乙烯(St)三元悬浮共聚合体系的聚合机理、共聚速率、非聚物组成及其特性粘度的影响因素。实验表明随着投料配比的改变,可分成四个不同聚合机理区域。St对VDC/AN/St三元悬浮共聚有缓聚作用。VDC三元悬浮共聚速率可用半经验模型,dC/dt=αC^β「Ⅰ」o^γexp(-γkdt)描述,由实验得到模型参数γ值为2.24,模型参数α、β是聚合温度与引发剂浓度的函数。VDC-AN-St三元悬浮共聚物存在着较宽的VDC组成分布,并受到单体AN水溶性的影响,经AN动态相平衡校正后,可预测VDC三元共聚物组成。VDC-AN-St共聚物的特性粘度随着转化率的升高而增大。在相同引发剂用量下,高转化率VDC-AN-St共聚物特性粘度的对数与温度的倒数成线性关系。 相似文献
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对以正丁烷(But)为反应介质的新型氯乙烯(VC)非均相聚合动力学和成粒机理进行了研究,根据VC-But二元体系气液平衡方程,由聚合过程气相压力或组成变化计算VC聚合转化率,VC非均相聚合的诱导期不明显,自动加速现象一般发生在聚合前、中期,后期聚合速率较小,新型VC非均相聚合PVC树脂的体粒径与悬浮PVC树脂相当,数均粒径较小,PVC颗粒由基本不熔结的初级粒子组成,颗粒内部初级粒子分布密度大,粒径大,孔隙率高;而在颗粒表层初级粒子分布密度高,粒径小,孔隙率低;树脂的增塑剂吸收率远大于悬浮PVC树脂,根据PVC树脂的颗粒特性和PVC与VC/But混合液的溶解度参数差异,推断聚合成粒机理为:PVC分子链在很低转化率时就从聚合介质中沉析出来并聚集形成微区,初级粒子和颗粒;后期成粒过程包括颗粒内部初级粒子的增长和向表层的离心聚集,颗粒对新形成的大分子链及其初级聚集体的捕捉等。 相似文献
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本文研究了丙烯腈(AN)、丙烯酸甲酯(MA)和甲基丙基烯磺酸钾(MAS)在水介质中的沉淀聚合反应。从基本反应和速率方程出发,应用连续搅拌釜(CSTR)的设计方程和聚合物颗粒表面的吸附方程,导出了丙烯腈连续水相沉积聚合的数模。结果表明,由模型算得的反应器出口处单体转化率和产品的平均分子量与实验值相吻合。 相似文献
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研究偶氮二异丁腈(AIBN)作光引发剂引发丙烯腈(AN)的光聚合,探讨了单体浓度、引发剂浓度、光照时间和环境温度对单体转化率、聚合物黏均相对分子质量的影响。总结出光引发剂C60-(SR)n(C60负载引发-转移-终止剂)与常规光引发剂AIBN引发AN光聚合的区别。 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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丙烯腈连续水相聚合的过程分析及控制 总被引:4,自引:1,他引:4
简要介绍丙烯腈水相聚合过程的机理及其数学模型,从而导出过程的参变数及对聚合过程目标值的影响。在此基础上,提出丙烯腈水相连续(共)聚合过程的控制方案。 相似文献
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用激光散射法对聚氯乙烯糊树脂(PPVC)浆料粒径及其分布和粉料颗粒粒径及其强度进行了测定和研究。结果表明:初级粒子的粒径大小和分布是决定PPVC树脂糊性能的关键因素;在一定范围内(30-60μm),二次粒子颗粒强度即二次粒子的解碎程度是影响PPVC树脂成糊性能的重要因素之一。 相似文献
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The water solubility of acrylonitrile (AN) and its effects on vinylidene chloride/acrylonitrile/styrene (VDC/AN/St) suspension copolymerization were investigated in this study. It shows that the VDC/St ratio and the presence of suspending agent have no obvious influences on AN phase partition between the monomer and aqueous phases, whereas the water solubility of AN increases as temperature increases. Polymerization in the aqueous phase occurs extensively with azobis(isobutyronitrile) (AIBN) as initiator, whereas with lauryl peroxide (LPO) as initiator, polymerization in the aqueous phase is negligible. Theoretical analysis and experimental results indicate that transport of the monomer molecule is possible during polymerization. Both VDC and AN transfer from the monomer phase to the aqueous phase when AIBN is used as initiator. AN transfers from the aqueous phase to the monomer phase for the polymerization system initiated by LPO. Sodium nitrite (NaNO2), but not sodium sulfide (Na2S), can be used to effectively inhibit polymerization in water and exerts less influence on the polymerization in the monomer phase. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1431–1438, 2001 相似文献
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Acrylonitrile/ammonium itaconate [AN/(NH4)2IA] aqueous deposited polymerizations were studied in this work. It shows that the polymerizations were influenced by various factors, especially the water solubility of AN. In the polymerization process, the system was as separated monomer and water phases, and AN transferred from monomer phase to water phase until the monomer phase disappeared. Because of the solubility of AN in water, the reactivity ratios of monomer calculated by Kelen‐Tudos method were different in various monomer contents. Although (NH4)2S2O8 was a water‐soluble initiator, there was a short amount of polymer formed in monomer phase. To inhibit the polymerization in monomer phase, two additives were used in the polymerization and experiment data indicated that the two inhibitors exert inhibitory role effectively in monomer phase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 904–908, 2006 相似文献
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Summary A novel concentrated emulsion polymerization procedure, in which the polymerization is initiated at room temperature and the heat generated by the reaction accelerates the process, is proposed. The polymerization of acrylonitrile (AN) and its copolymerization with vinylidene chloride (VDC) are used as examples. AN (alone or with a comonomer) containing an oxidant was first dispersed in water to generate a concentrated emulsion. The polymerization of the monomers was initiated at room temperature by introducing an aqueous solution containing a mixture of reductants (ferrous sulfate and sodium metabisulfite) into the concentrated emulsion. The heat generated in the system increased its temperature and accelerated the polymerization. The polymerization was completed in one hour with conversions higher than 90%. The small volume of the continuous phase in a concentrated emulsion constitutes an advantage of the procedure, since only a small amount of the produced heat is used for its heating. In addition, because the reductant, which is present in the water phase, together with the oxidant, which is present in the oil phase, constitute the initiator, the large oil-water interfacial area of the concentrated emulsion constitutes an additional advantage. 相似文献
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利用2,2'-偶氮(2-脒基丙烷)二氯化氢(AIBA)引发剂与纳米氧化硅粒子的静电作用而使AIBA吸附在纳米氧化硅表面,进而引发丙烯腈-甲基丙烯酸甲酯(AN-MMA)原位乳液聚合.考察了AIBA浓度和反应温度对AN-MMA原位乳液聚合动力学的影响以及氧化硅含量对AN-MMA共聚物/纳米氧化硅复合乳胶粒径分布和形态的影响.结果表明:聚合速率随AIBA浓度和聚合温度的升高而增大; AIBA浓度相同时,原位乳液聚合速率小于普通乳液聚合;AN-MMA共聚物/纳米氧化硅复合粒子粒径随纳米氧化硅含量增加而增大;原位乳液聚合得到的复合胶粒表面粗糙,当纳米氧化硅质量分数为10%时,纳米氧化硅与聚合物乳胶粒子复合良好;当纳米氧化硅质量分数为20%和30%时,有部分纳米氧化硅粒子与乳胶粒子分离而分散在连续相中. 相似文献
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Mengmeng Yu Hou Chen Ying Liang Hengli Cui Wenying Zhou Xianqiang Cui Dongmei Li 《应用聚合物科学杂志》2009,111(6):2761-2768
Porous acrylonitrile (AN)/itaconic acid (IA) copolymers were successfully prepared by suspended emulsion polymerization for the first time, with potassium peroxydisulfate (KPS) as an initiator, poly(vinyl alcohol) (PVA) as a dispersant agent, and Span80 as an emulsifier. The effects of the water/monomer mass ratio, agitation conditions, KPS concentration, PVA concentration, Span80 concentration,s and IA concentration on the average particle size and size distribution, particle morphology, and porosity of the AN/IA copolymers were investigated. The results show that the final AN/IA copolymers formed with agglomerates of primary particles had a porous structure, low particle density, and uniform particle size and did not agglomerate easily between the particles. The preparation conditions for the AN/IA copolymers were optimized as follows: (1) the water/monomer mass ratio was 0.3 : 1; (2) the concentrations of KPS, IA, PVA, and Span80 were 0.5, 12.4, 0.1, and 0.5 wt %, respectively, based on the weight of AN separately; (3) the agitation rate was 400 rpm; (4) the polymerization temperature was 70°C; and (5) the reaction time was 3 h. The size of the final AN/IA copolymer particles was in the range 200–400 μm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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