共查询到17条相似文献,搜索用时 62 毫秒
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通过悬浮聚合法制取了聚甲基丙烯酸甲酯(PMMA)。主要研究了分散剂、引发剂、温度、搅拌速度以及水和单体的比对聚合物的影响。结果表明:当单体的量为12mL时,水和单体比为5∶1(体积比);引发剂的量为0.16g;分散剂的量为MgCl2:3mL、NaOH:6mL;温度控制在75~78℃,反应约1.5h;搅拌速度为250r/min的实验条件下,制得了颗粒均匀、透明度良好、产率较高的聚甲基丙烯酸甲酯。 相似文献
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《应用化工》2022,(Z1)
利用NaOH和MgCl_2反应制备悬浮聚合分散剂氢氧化镁,以过氧化二苯甲酰(BPO)为引发剂,进行苯乙烯(St)悬浮聚合。研究了分散剂用量、引发剂用量、水和单体比、搅拌速度、反应温度及反应时间对聚苯乙烯(PS)珠粒大小、均匀程度和产率的影响。结果表明:氢氧化镁作为分散剂有很好的稳定作用,当苯乙烯为12 mL,适宜的反应温度为95℃;MgCl_2(1 mol/L)4 mL,NaOH (1 mol/L)8 mL;BPO 0.35g;V(水)∶V(St)=4.0∶1;搅拌速度300 r/min,反应时间80 min,制得的PS珠粒透明度良好,颗粒大小均匀,粒径在1~2 mm,收率可以达到90%。 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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Vent D. P. Lopatin A. G. Brykov B. A. Savel’yanov V. P. 《Theoretical Foundations of Chemical Engineering》2020,54(5):886-893
Theoretical Foundations of Chemical Engineering - The reactor dynamics of suspension polymerization of styrene has been studied in a specially designed unit controlled by a computer. It is found... 相似文献
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The suspension polymerization of styrene in water with hydroxyapatite and calcium carbonate as Pickering emulsifiers and sodium dodecylbenzenesulfonate (NaDDBS) and poly(vinylpyrrolidone) (PVP) as surfactants was investigated. The adsorption of NaDDBS and PVP at the surface of the solids, the surface tensions of the aqueous solutions, the interfacial tensions between the aqueous solutions and styrene and the contact angles versus water and styrene, respectively, were measured in dependence of the surfactant and the solids concentrations. In contrast to assumptions in literature, the adsorption equilibrium was found to be far on the side of desorption. The decrease of surface and interfacial tensions with increasing surfactant concentrations especially in the case of NaDDBS were stronger than expected due to an enhanced dissolution of the solids caused by the surfactant. The contact angles of the binary systems were measured by the Washburn method. Surprisingly their absolute values depended on the packing densities of the solids. The theory of Good and Girifalco was used to calculate the interfacial tensions and the contact angle between solids and water in the ternary system solid/water/styrene. For NaDDBS, the contact angle was higher than 90° even at very low surfactant concentrations, causing unstable suspensions. Therefore, the modulation effect of NaDDBS seems to be very low and developing very slowly due to the slow adsorption process. Also for PVP the contact angle was higher than 90°, however, stable suspensions were obtained. This may be due to the fact that PVP stabilizes polymer suspensions also without any solids and that in such a system the stabilizing effect of solids is of minor importance. In the case of PVP the particle size of polystyrene could be controlled by the PVP concentration and the length of the contact time between PVP and solid. 相似文献
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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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采用自由基原位悬浮聚合方法,由苯乙烯/纳米无机粒子(NIP)聚合制备聚苯乙烯纳米复合材料(PSNC),再以戊烷为发泡剂制备了可发性聚苯乙烯纳米复合材料(EPSNC),筛选了NIP改性剂的种类。利用凝胶渗透色谱仪和热重分析仪对EPSNC进行表征,研究了EPSNC的分子结构和热性能,采用扫描电子显微镜对EPSNC泡体内部微观形貌进行表征,研究NIP含量对其泡体微观形貌的影响规律。结果表明,以钛酸酯偶联剂改性NIP (M NIP)聚合产率最高;M NIP用量在一定范围内对EPSNC的相对分子质量影响不大,但相对分子质量分布变窄;含有M NIP的EPSNC的热稳定性明显提高;EPSNC发泡时NIP起成核作用,M NIP能够均匀地分散在EPSNC中,其泡孔堆积有序,细密一致,且多为闭孔结构。 相似文献