PBA/PMMA核壳结构乳胶粒子粒径分析

采用种子乳液聚合制备出了PBA/PMMA核壳结构乳胶粒子，研究并分析了MMA在3种不同投料方式（间歇法、半间歇法和平衡溶胀法）下粒子粒径变化情况。实验发现第二单体采用间歇法投料可获得较理想的核壳结构乳胶粒。     

不同粒径的PBA/PMMA乳液的合成及表征

采用乳液聚合合成了以聚丙烯酸丁酯(PBA)为核,聚丙烯酸甲酯(PMMA)为壳的胶乳。重点研究了聚合条件对核层粒径的影响。通过粒度分析对其进行表征。结果表明:通过改变聚合工艺可以得到粒径不同的PBA/PMMA胶乳,且具有明显的核壳结构。     

悬浮-乳液耦合聚合制备大粒径核-壳结构PS/PMMA复合粒子

采用在苯乙烯(St)悬浮聚合不同时期滴加甲基丙烯酸甲酯(MMA)乳液聚合组分的悬浮-乳液耦合聚合方法,制备大粒径核-壳结构复合粒子。研究发现：在St悬浮聚合初期和宏观成粒基本完成的聚合后期滴加MMA乳液聚合组分,分别得到由初级粒子凝并的非核-壳结构粒子和核-壳结构不完整的复合粒子,粒径分布较宽;在St悬浮聚合中期滴加MMA乳液聚合组分,MMA和PMMA乳胶粒子易于向PS粒子扩散或粘并,制备得到平均粒径大于100gm、粒径分布窄和核-壳结构良好的PS／PMMA复合粒子。     

PMMA/PAN核-壳粒子制备工艺研究

加入适量的引发剂,通过无皂乳液聚合,以聚甲基丙烯酸甲酯( PMMA)核体为种子乳液,制备了PMMA/PAN核-壳乳液.实验中分别对引发剂量、丙稀腈( AN)滴加量对PMMA/PAN壳层厚度及其粒径和粒径分布的影响进行了较详细的研究,确定了种子乳液聚合法制备PMMA/PAN核-壳结构聚合物粒子的实验方法及条件.通过激光粒度仪、扫描电镜和透射电镜对核-壳粒子的形态结构进行了表征,证明了PMMA/PAN复合粒子的核-壳结构.     

核壳结构聚合物乳液乳胶粒粒径及重量分布测试

对核壳结构聚合物乳液乳胶粒的粒径及其分布进行了测试,并与同一聚合物体系的其它乳液加以比较、分析,得出其粒径最小、分布最均匀的重要结论.     

多层核壳结构丙烯酸酯乳液的粒径控制

研究了加料工艺、引发剂体系、乳化剂用量及复配比、聚合温度等因素对多层核壳结构乳胶粒子粒径的影响,采用连续滴加单体的加料工艺,选用复配乳化剂体系,在较低的乳化剂用量条件下,使用高效低温引发剂,在50℃引发聚合,合成了固含量为42%,平均粒径为64.9 nm,窄分布的具有多层核壳结构的聚丙烯酸酯乳液。     

PBA/PMMA核壳结构乳液聚合的动力学研究

采用重量分析法对PBA／PMMA体系核壳结构乳液聚合物动力学进行了研究，并计算了乳化剂用量，引发剂浓度与第一单体和第二单体聚合速率的定量关系。同时研究了温度对第一单体和第二单体聚合速率的影响。聚合速率，特别是第二单体的聚合速率对核壳结构的形成有很大的影响。     

核壳聚合与核壳结构聚合物乳液

对核 /壳乳液聚合机理、方法、工艺以及核 /壳结构聚合物乳液的制备和性能进行了综述 ,重点讨论了各种因素对核 /壳结构聚合物乳胶粒子形态的影响 ,并回顾了核 /壳乳液聚合最新的研究动态。     

PBA/MMA-MAA核-壳型乳液聚合研究

本文以种子乳液聚合法制备了PBA／MMA－MAA核－壳型复合取合物乳液。讨论了复合聚合物时引发剂用量和补加乳化剂用量对聚合反应及乳胶粒及其分布的影响。结果表明，引发剂用量控制在0．2％（wt)，乳化剂用量在0．75％（wt)，可制得粒径分布较窄且性能良好的核－壳型聚合物乳液用于毛面剂中。     

Study of the synthesis and properties of PBA/PS/PMMA latex interpenetrating polymer networks

In this article, we use the technique of multistage emulsion polymerization to synthesize the LIPN PBA/PS/PMMA and use the gravimetric analysis method to study the apparent kinetics of the reaction process and to investigate the influence of the concentration of the initially emulsifying agent, the initiator, and the extent of the crosslinking on the distribution of the particle diameter and the dynamic mechanical properties of the products.     

Particle size distribution control in emulsion polymerization

Effects of the operating policies—the initial initiator amount; the initial emulsifier amount; the monomer addition mode: batch or semibatch; and the monomer addition rate under “monomer‐starved conditions” for the control of particle size distribution (PSD)—were studied through a model that simulates batch and semibatch reactor operations in conventional emulsion polymerization. The population balance model incorporates both the nucleation stage and the growth stage. The full PSDs were reported, which have normally been omitted in earlier studies. It was shown through simulations that the broadness of the distributions, both initial (obtained after the end of nucleation) and final (after complete conversion of monomer), can be controlled by the initial initiator amount and the emulsifier amount. The higher initiator amounts and the lower emulsifier amounts favor narrower initial and final distributions. The shape of the initial PSDs and the trends in the average size and range were preserved with subsequent addition of monomer in the batch or in the semibatch mode, although the final PSD was always considerably narrower than that of the initial PSD. The addition of monomer in the semibatch mode gave narrower distribution compared to that of the batch mode, and also, lower monomer addition rates gave narrower distributions (larger average sizes), which was a new result. It was further shown through simulations that, under monomer‐starved conditions, the reaction rate closely matched the monomer feed rate. These conclusions are explained (1) qualitatively—the shorter the length of the nucleation stage and the larger the length of the growth stage (provided the number of particles remains the same), the narrower is the distribution; and (2) mathematically—in terms of the “self‐sharpening” effect. Experimental evidence in favor of the self‐sharpening effect was given by analyzing the experimental particle size distributions in detail. The practical significance of this work was proposed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2884–2902, 2004     

PMMA/PAN核壳复合粒子的制备与表征

用无皂乳液聚合法制备粒径分布较窄的单分散聚甲基丙烯酸甲酯(PMMA)乳液粒子后,以此乳液粒子为种子,以丙烯腈为壳层单体,用种子乳液聚合法制备了粒径分布更窄、具有核壳结构形态的PMMA／聚丙烯腈(PAN)复合粒子,测定了核及核壳粒子粒径及其分布,并用透射电镜表征了其核壳形态特征。结果表明,PMMA／PAN核壳粒子的壳层厚度约为20nm,粒径分布要比PMMA粒子的窄。     

Particle size distribution and molecular size distribution of polymers in soap-free emulsion polymerization of styrene

Polystrene (PS) particles, generated from soap-free emulsion polymerization of styrene monomer, water, and potassium persulfate, were investigated by photon correlation spectroscopy (PCS) and TEM. The particle size distribution (PSD) was quite uniform. From the data of PCS, it could be said that lots of particles flocculated in the final stage of reaction. It was also deduced from the molecular weight distribution (MWD), measured by GPC, that, during the early stage of reaction, molecules with low molecular weight (<4000) might exist and the particles were perhaps formed through micellar-type nucleation mechanism. When initiator concentration increased, reaction rate increased but weight average molecular weight, tensile modulus, and elongation decreased. The number density of particles was found to be proportional to 0.49 power of initiator concentration. However, monomer concentration did not seem to have any great effect on all of them above.     

SiO2/PBA/PMMA和CaCO3/PBA/PMMA核壳结构纳米材料的制备与表征

利用γ 甲基丙烯酰氧丙基三甲氧基硅烷(KH-570)对纳米二氧化硅和纳米碳酸钙有机化处理,红外光谱(FTIR)测试表明,纳米二氧化硅通过有机化处理可以在表面接枝上有机基团,表现在表面处理后波数在2955,2860和1460cm-1有甲基的吸收峰,而纳米碳酸钙由于表面上已有有机基团,表面上没有接枝上新的有机基团。然后利用乳液聚合的方法制备了以表面处理过的纳米二氧化硅或纳米碳酸钙为核,丙烯酸丁酯和甲基丙烯酸甲酯为壳的有机-无机杂化材料。用凝胶渗透色谱(GPC)测定了其各种相对分子质量及其相对分子质量分布后发现,加入纳米碳酸钙后其相对分子质量有所降低,相对分子质量分布变宽;加入纳米二氧化硅后其相对分子质量有所增大,相对分子质量分布变窄。透射电镜(TEM)和粒度分布仪测试表明,乳液聚合前粒子大部分以团聚体的形式存在,粒径在1～2μm左右;乳液聚合后粒子大部分以纳米尺寸存在,粒径10～200nm。实验证明,乳液聚合是制备有机-无机纳米杂化材料非常有效的方法。     

GAD室温自交联乳液的粒径及其分布

合成得到了含环氧基、羧基和胺基的室温自交联乳液,研究了聚合工艺和乳胶粒结构及组成对乳液粒径及其粒径分布的影响。结果表明：聚合温度对乳液粒径及其分布的影响较小,加大乳化剂用量和乳化单体滴加速率使乳液粒径减小,粒径分布变窄;壳层甲基丙烯酸二甲氨基乙酯用量增加,致仗乳液粒径增大和粒径分布变宽;在合适的中间层分率下获得粒径较小和粒径分布较均匀的乳液;中间层引入（甲基）丙烯酸可减小乳胶粒径,并使粒径分布更均匀。     

Particle size distribution in olefin continuous stirred-bed polymerization reactors

The control of polymer particle size and PSD is of industrial importance. Very fine particles pack poorly, thereby limiting reactor capacity, and present a dust explosion hazard. In olefin polymerization, a particle size distribution (PSD) in the polymerization reactor has been derived using population balances. Three reasonable reaction mechanisms for Ziegler-Natta catalysts, i.e., a simple reaction model, an active site reduction model, and a two sites model, have been used to derive the average number of active sites. It was observed that the PSD depends not only on residence time, but also on the reaction mechanism. It was also found that multiple active sites change the PSD slightly. The PSD, however, does not depend on initial catalyst volume.