超声均质微悬浮聚合制备亚微米级聚苯乙烯胶粒

以苯乙烯St为代表性单体,以聚乙烯醇PVA为分散剂,以十六烷HD为助稳定剂,以亚硝酸钠NaNO₂为水相阻聚剂,通过基于超声均质化的微悬浮聚合制得了一系列亚微米级聚苯乙烯胶粒。对亚微米级单体液滴的均质化产生及后续聚合过程中分散相尺寸的变化进行了考察。发现超声均质化和高分子分散剂的结合有利于制备粒径小、分布窄的稳定微悬浮液滴,而吸附于液滴表面的高分子分散剂、油相内的助稳定剂及水相中的阻聚剂的协同作用能使聚合过程较好地保持分散相原有的粒径大小及分布。因而通过改变超声均质强度,可较容易地在0.5～3.5 μm范围内自由调节胶粒的平均粒径。相对于常规的剪切均质微悬浮聚合,超声均质微悬浮聚合可更好地填补（细）乳液聚合与悬浮聚合在粒径分布范围上的间隙,有望高效、高容量地微胶囊化包裹亚微米级目标内容物。     

超声均质微悬浮聚合制备亚微米级聚苯乙烯胶粒

以苯乙烯St为代表性单体,以聚乙烯醇PVA为分散剂,以十六烷HD为助稳定剂,以亚硝酸钠NaNO2为水相阻聚剂,通过基于超声均质化的微悬浮聚合制得了一系列亚微米级聚苯乙烯胶粒。对亚微米级单体液滴的均质化产生及后续聚合过程中分散相尺寸的变化进行了考察。发现超声均质化和高分子分散剂的结合有利于制备粒径小、分布窄的稳定微悬浮液滴,而吸附于液滴表面的高分子分散剂、油相内的助稳定剂及水相中的阻聚剂的协同作用能使聚合过程较好地保持分散相原有的粒径大小及分布。因而通过改变超声均质强度,可较容易地在0.5~3.5μm范围内自由调节胶粒的平均粒径。相对于常规的剪切均质微悬浮聚合,超声均质微悬浮聚合可更好地填补(细)乳液聚合与悬浮聚合在粒径分布范围上的间隙,有望高效、高容量地微胶囊化包裹亚微米级目标内容物。     

氯乙烯SET-DT悬浮聚合动力学和成粒过程的相互关系

以碘仿为引发剂、连二亚硫酸钠/碳酸氢钠为催化体系、聚乙烯醇(PVA)和/或纤维素衍生物(MC)为分散体系,进行氯乙烯单电子转移-蜕化链转移(SET-DT)活性自由基悬浮聚合,采用在线示踪气相色谱法和激光粒度分析系统研究分散剂种类和浓度、搅拌转速等对聚合动力学和单体液滴/聚合物颗粒粒径分布的影响。发现在相同搅拌转速下,以MC为分散剂的氯乙烯聚合速率最大,以PVA为分散剂时反应速率最小;分散剂种类固定时,聚合速率随分散剂浓度增大而增大。SET-DT悬浮聚合过程中,水相连二亚硫酸钠分解产生的自由基向单体液滴的扩散速率与液滴粒径分布和皮膜结构有关,因此聚合成粒过程影响聚合动力学。尽管不同条件下的聚合均经历液-液分散、液滴黏并、树脂颗粒稳定(转化率>30%)等成粒阶段,但各阶段的液滴/颗粒平均尺寸随分散体系和搅拌转速的变化而变化,引起聚合速率变化;采用MC为分散剂得到的PVC树脂皮膜少,有利于水相产生的自由基向单体相的扩散,聚合速率大。     

对原位聚合法制备微胶囊技术的研究

本文讨论了用原位聚合法制备微胶囊的工艺，研究了影响微胶囊粒径大小，分布和影响微胶囊释放性能的各种因素。实验结果表明：随乳化分散剂用量的增加，搅拌速度和搅拌时间的增加，微胶囊粒径变小，粒径分布变窄。微胶囊壁材的聚合反应速率大，交联密度高，则孔隙率大，释放速率快；而壁膜厚度增大，则其释放速率减慢。     

氯乙烯微悬浮聚合成粒机制探讨

以不同均化方式得到微悬浮分散液,再经微悬浮聚合制备了PVC糊树脂。首先以三氯乙烯为氯乙烯单体的模拟液,研究了十二烷基硫酸钠乳化剂/十六、十八混合醇助稳定剂复合胶束和单体亚微液滴的形成过程,发现复合胶束的形成过程和三氯乙烯溶胀进入复合胶束形成亚微液滴的过程均受扩散动力学控制,延长溶胀时间及施加高速剪切分散可以强化溶胀过程,复合胶束对单体具有"超级溶胀"能力。然后采用搅拌溶胀和高速剪切微悬浮聚合得到PVC乳胶粒子,发现两者形貌相同,而前者粒径略大、分布略宽;延长搅拌溶胀时间,可使粒度分布更接近高速剪切均化微悬浮聚合得到的PVC乳胶粒子的粒度分布。     

悬浮聚合法制备PGMA-MMA-EGDMA共聚物交联微球

以甲基丙烯酸缩水甘油酯(GMA)为主单体、甲基丙烯酸甲酯(MMA)为共单体、乙二醇二甲基丙烯酸酯(EGDMA)为交联剂、聚乙烯醇(PVA)为分散剂,采用悬浮聚合法制备了三元共聚交联微球GMA-MMA-EGDMA,采用FT-IR和SEM对其化学结构和微球进行了表征,考察了分散剂用量、搅拌速度、油/水相比、交联剂用量、NaCl用量对交联微球的成球性能及粒度的影响规律. 结果表明,分散剂用量、搅拌速度与油/水相比是影响交联微球制备的主要因素,当分散剂用量<1%、搅拌速度<250 r/min、油/水相比>1:4(j)时,共聚合体系中均不能成球. 在水相中加入电解质NaCl有助于成球,交联微球的粒径随NaCl用量增大而减小. 控制悬浮聚合的反应条件可以制备出球形度好、粒径在100~400 mm范围内可控的交联微球GMA-MMA-EGDMA.     

种子微悬浮聚合法制备微胶囊相变材料

以苯乙烯(St)和二乙烯基苯(DVB)为壁材聚合单体,偶氮二异丁腈(AIBN)为引发剂,羟丙基纤维素(HPC)和碳酸钙(Ca CO3)为复合分散剂,用种子微悬浮聚合法制备交联聚苯乙烯(PS)包覆硬脂酸丁酯微胶囊。用扫描电子显微镜(SEM)、差示扫描热量仪(DSC)、粒度分析仪和热重分析仪(TG)表征了微胶囊的形貌和性能,考察了聚合方法、交联剂和分散剂对微胶囊形貌结构和性能的影响。结果表明,种子微悬浮聚合法制备的微胶囊呈粒径分布均匀、规整的球形结构,与常规悬浮聚合法制备的微胶囊相比,相变潜热提高了41.6%,包覆率提高15.1%;随着DVB用量的增加,壁材的交联度增大,微胶囊密封性和热稳定性提高;采用复合分散剂且m(HPC)∶m(CaCO_3)=2.2∶1时,微胶囊相变潜热提高了26.8%。     

我厂聚合釜搅拌改造初步小结

一、前言 提高PVC树脂质量,改善PVC树脂颗粒形态与PVC生产的工艺配方,聚合釜的搅拌性能均有着密切的关系。 在一定生产工艺配方条件下,适当增强搅拌能力,以使分散体系质点动态平衡次数增加,分散剂溶解度增加,液滴分合过程延长。而在体系稳定情况下,在大液滴内有足够的分散剂起着分散和保护作用时,液滴内所包含着的许多小液滴在引发剂作用下,就形成大颗粒内有许多小颗     

悬浮聚合法合成热膨胀微球

以丙烯腈(AN)、甲基丙烯酸甲酯(MMA)为单体,异辛烷(IO)为发泡剂,纳米二氧化硅为分散剂,采用悬浮聚合的方法制备出了热膨胀型微球。利用红外光谱(IR)、热分析(TGA)等手段对热膨胀微球进行了表征,并对微胶囊的形貌、粒径、发泡倍率等特征进行了研究。研究结果表明,通过悬浮聚合的方法可以得到粒径在1-100 μm的热膨胀微球,其发泡倍率高且粒径分布均匀。     

2％阿维菌素微胶囊水悬浮剂的制备

以甲苯二异氰酸酯和水溶性成膜单体乙二胺为壁材,采用界面聚合法制备阿维菌素微胶囊水悬浮剂.研究了分散剂、溶剂、芯壁比、乳化搅拌速度、聚合反应时间对微胶囊包囊率和包囊形态的影响.结果表明:该法芯材比可达到6-7.5,体系浓度可达到10％,而且制得微胶囊阿维菌素包囊率＞90％,粒径≤10μm,粒径分布均匀,贮存稳定性合格,可...     

In situ polymerization of uniform poly(urea–formaldehyde) microcapsules containing paraffins under the high-speed agitation without emulsifier

In this paper, uniform spherical poly(urea–formaldehyde) (PUF) microcapsules containing paraffins, which can be used as phase change materials for energy storage, were prepared by in situ polymerization method under high-speed agitation (≥10,000?rpm) without emulsifier. The influence of high-speed agitation on particle size of as-prepared microcapsules and the tightness of microcapsules were also investigated. The results show that, all the microcapsules have <10?μm mean particles-size and narrow-size distribution, and the mean particle size decreases with the increase of agitation rate. Furthermore, when the agitation rate is >16,000?rpm, the effectiveness of reducing particle size by high-speed stirring is not as remarkable as that of lower speed agitation. In order to gain good tightness of PUF microcapsules under the high-speed agitation conditions, the final pH value of reaction solution should be lower down compared with that of conventional agitation. In our investigation, when the agitation rate was 10,000?rpm, microcapsules fabricated at pH value <2.0 were sealed and own good tightness, however, those fabricated at pH value >2.2 were not sealed.     

Study of Some Variables Affecting Particle Size and Particle Size Distribution of Suspension Polymerization of Methyl Methacrylate

A laboratory reactor was designed and constructed to study the effect of both speed of agitation and a concentration of suspension stabilizer on particle size and particle size distribution during the suspension polymerization of methyl methacrylate. It was concluded that the average particle size of the prepared polymer powder is directly proportional to the speed of agitation and is inversely proportional to the stabilizer concentration. New empirical equations correlating the average particle size and the particle size distribution (PSD) were derived from the study.     

搅拌转速对悬浮PVC树脂平均粒径的影响

在5L小釜中分别采用恒转速和变转速工艺进行氯乙烯(VC)悬浮聚合,考察粒径随转化率的变化规律,发现两者规律相似,即在低转化率时粒径随转化率的增加而逐渐增大,当转化率约为15%以后粒径几乎不再变化.同时发现搅拌转速、分散剂用量和聚合温度等对上述转化率～粒径变化规律几无影响,只是粒径大小的不同.将变转速工艺应用于大型釜生产中,考察变速时间、前转速及后转速对最终树脂粒径及其分布的影响,计算两工艺的生产能耗,发现变转速聚合除了有利于树脂颗粒的形成外,还可以降低搅拌功率的消耗,节约能源.     

窄粒径分布的液体石蜡相变微胶囊制备及性能表征

目前相变微胶囊的制备普遍采用传统的机械搅拌乳化方法,获得微胶囊的粒径大小难以控制,粒径分布范围较大。本工作采用快速膜乳化技术结合原位聚合法获得窄粒径分布的液体石蜡/密胺树脂相变微胶囊。研究发现,过膜压力和过膜次数对相变微胶囊的粒径大小和分布影响较大,当微孔玻璃膜孔径固定时,调节过膜压力和过膜次数可以控制微胶囊的粒径大小和分布。当使用孔径为10.1 μm的微孔玻璃膜时,采用过膜压力为0.2 MPa、过膜次数为4次时,可以获得粒径分布最窄的液体石蜡相变微胶囊。此时微胶囊的平均粒径为10.84 μm,相对标准偏差仅为0.16,远小于机械搅拌乳化制备的微胶囊的粒径相对标准偏差。且微胶囊表面光滑致密,无明显团聚,具有良好的耐热性能和冷/热循环稳定性,微胶囊包裹率约为80%。此外,快速膜乳化技术的引入大大提高了乳化效率,从而显著提高了微胶囊制备效率,对其他窄粒径分布的低温烷烃相变微胶囊的批量化制备具有重要意义。     

The electric response behavior and microencapsulation of the pigment phthalocyanine green G using interfacial polymerization

The polyamide microcapsules for the electrophoretic display have been prepared via interfacial polymerization. The core material of the microcapsules is electrophoretic fluid consisted of pigment phthalocyanine green G (CAS No. 1328-53-6) modified with octadecylamine, tetrachloroethylene, and polyoxyethylene octylphenol ether (OP-10). The wall of the polyamide is synthesized from paraphthaloyl chloride and diethylenetriamine. FT-IR indicated that octadecylamine was bonded to pigment phthalocyanine green G with the hydrogen bond. The effect of the amount of octadecylamine on the dispersibility of the pigment suspended in tetrachloroethylene was investigated. Compared to the unmodified pigment, the dispersibility of the modified pigment was improved by 66.7%. The modified pigment migrated to the positive electrode under the direct voltage and the electric response time was about 85 s in 20 V/mm. The average particle size of microcapsules decreased from 834.5 to 258.2 nm as the dosage of OP-10 increased, and the microcapsule yield reached maximum of 83.5% at the OP-10 concentration of 1.5 wt%. With the reduction of the core/wall weight ratio in the range from 1:6 to 1:14, the average particle size improved from 267.4 to 554.4 nm. However, the maximum of the microcapsule yield was 87.6% at the core/wall weight ratio of 1:10. The microcapsule yield reached a peak of 87.6% as the pH value was 12. The average particle size of the microcapsules that obtained at 25 °C was 327.4 nm, which was smaller than those prepared in other temperatures. The formed polyamide microcapsules had a regular spherical shape.     

Acrylic latices stabilized by polymerizable non-ionic surfactant

The final latex particle size is controlled by the concentration of polymerizable non-ionic surfactant NE-40 in the emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA). The particle size decreases with increasing NE-40 concentration and increases with increasing persulphate initiator concentration. The dependence of particle size on the initiator concentration does not follow conventional Smith–Ewart theory, which is attributed to the bridging flocculation process during the particle nucleation period. The differences in the particle nucleation and growth stages and colloidal stability observed in the NE-40 and nonyl phenol-40 mol ethylene oxide adduct (NP-40) stabilized systems can be attributed to the different distribution patterns of surfactant molecules in the particles. Experimental data also indicate that the particle size decreases with increasing electrolyte concentration, or agitation speed. The total scrap, presumably caused by the bridging flocculation process, increases rapidly with increase in the NaCl concentration The amount of large flocs formed during polymerization is generally greater for the run operated at higher agitation speed. As expected, the latex products stabilized by non-ionic surfactants show excellent stability toward added sodium salt.     

微流控技术制备聚酰胺微胶囊的工艺研究

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。