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含丙烯酸的苯丙共聚乳液乳胶粒形态的电镜研究 总被引:2,自引:1,他引:2
采用透射电镜观测了苯乙烯-丙烯酸丁酯-丙烯酸乳液共聚体系的乳胶粒形态,讨论了组分含量、共聚物链柔性和乳液pH值等因素对乳胶粒形态、乳液粘度及成膜性的影响.结果表明:软单体的加入和体系pH值的提高将促进乳胶粒的粘连成膜和溶涨及部分聚合物的溶解.羧基主要富集于乳胶粒表面. 相似文献
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首先采用无皂乳液聚合法合成了表面带负电荷、粒径为360 nm的单分散聚苯乙烯(PSt)乳液,并利用聚乙烯亚胺(PEI)在25℃下对PSt乳胶粒表面进行修饰,得到了表面带有正电荷的PSt种子乳液;然后以乙醇和水的混合物为反应介质,采用种子乳液加入法,使钛酸正丁酯(TBT)在修饰后的乳胶粒表面进行水解与缩合,制备出了核壳结构PSt/TiO2复合微球,利用电镜对复合微球的结构形态进行了表征.结果表明,PSt乳液改性时体系的zeta电位随着PEI用量的增加而升高,当PEI用量为PSt聚合物重量的15%时,体系的zeta电位从原来的-40.3 mV升高到了38.3 mV,达到对PSt乳胶粒表面改性的最佳值;在制备PSt/TiO2复合微球时,TiO2包覆量随着反应时间的延长而增加,反应7 h时达到90.2%的最大值;随介质中水含量的增加,吸附到复合微球表面上的TiO2纳米颗粒逐渐减少,复合微球表面逐渐变得光滑,当EtOH/H2O质量比为100/6.0时,得到结构均一、壳层厚度为29 nm的核壳结构PSt/TiO2复合微球. 相似文献
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以氯丁胶乳(Pa)为种子乳液,甲基丙烯酸甲酯(Pb)为第二单体,采用种子乳液聚合法,制备了氯丁胶乳-聚甲基丙烯酸甲酯复合乳胶粒。 热力学分析表明,当Pb的体积分数Φb<0.69时,可同时形成Pa-Pb型正核-壳和(Pa+Pb)分离型乳胶粒,当Φb>0.69时,形成Pb-Pa型翻转型核壳结构乳胶粒,并伴有Pa-Pb型正核-壳结构乳胶粒的形成。 动力学分析表明,引发剂类型、第二单体的加入方式、种子乳胶粒的交联、单体/聚合物质量比是影响乳胶粒形态的主要因素。 采用水溶性引发剂过二硫酸钾(KPS),以饥饿态方式加入单体,氯丁胶乳 聚甲基丙烯酸甲酯(PCR-PMMA)复合乳胶粒呈现正核-壳结构,以充溢态方式加入单体则不能形成明显的核-壳结构;而以油溶性偶氮二异丁腈(AIBN)为引发剂时,单体无论以充溢态方式加入还是饥饿态加入均倾向于形成翻转核-壳型粒子。 在种子乳胶粒中加入一定量交联剂二缩三乙二醇二甲基丙烯酸酯,有利于形成明显的正核壳结构。 以饥饿态进料,KPS为引发剂时,随着单体用量增加,壳层变厚,仍呈正核-壳结构,与热力学分析结果相吻合;以AIBN为引发剂时,随着单体用量增加,PCR-PMMA复合乳胶粒逐渐由翻转核壳型结构变为互穿结构。 相似文献
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以环氧树脂E-44、2-氨基-5-磺酸基苯甲酸、乙二醇丁醚和正丁醇为原料,合成一种新型阴离子环氧乳化剂EP-D;同时,E-44和聚乙二醇(PEG6000)以摩尔比2∶1反应,合成端环氧基非离子环氧乳化剂EP-PEG;将EP-D与EP-PEG按不同质量比复配获得不同配比的EP-D/EP-PEG水性环氧复合乳化剂。 分别研究了EP-D/EP-PEG及EP-PEG在环氧树脂中加入质量分数为6%~12%时的乳化性能及形成乳液的表面张力、电导率和胶粒的Zeta电位、粒径。 结果表明,当EP-D和EP-PEG以质量比3∶5复配,总加入质量分数为9%时,制备的环氧乳液性能最佳。 与EP-PEG形成的环氧乳液相比,复配环氧乳化剂用量少,乳液铺展性好、稳定性高,且乳液在相反转时的固含量提高了10%以上。 复配环氧树脂乳液中胶粒的Zeta电位为-41.9 mV、粒径为342 nm、表面张力为25.5 mN/m、粘度为14 mPa·s。 这表明利用乳化剂EP-D与EP-PEG复配新合成的EP-D/EP-PEG水性环氧复合乳化剂可制备稳定性好,固含量高的乳液。 相似文献
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通过乳酸催化脱水制备丙烯酸具有良好的应用前景。为了对其中的催化过程进行有效、及时的监控,建立了一种同时测定乳酸及丙烯酸的阴离子交换色谱法(AEC)。选择Metrohm A Supp 5阴离子交换柱(150 mm×4.0 mm),以2 mmol/L Na2CO3+2 mmol/L NaHCO3混合水溶液为流动相,采用化学抑制电导检测技术,乳酸和丙烯酸在6 min内即可实现完全分离。乳酸和丙烯酸工作曲线的线性范围分别为0.1~500 mg/L和0.1~200 mg/L,检出限分别为0.030 mg/L和0.035 mg/L,加标回收率分别为100.7%~106%和99.6%~103%,相对标准偏差分别为2.16%~2.49%和2.42%~2.48%。该方法准确、快速、灵敏、重现性好。 相似文献
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Fast‐swelling micrometer sized superabsorbents were synthesized through a rapid solution polymerization of n‐vinyl‐2‐pyrrolidone (NVP) and partially neutralized acrylic acid (PNAAc) under normal atmospheric conditions using N,N'‐methylene bisacrylamide (MB) as crosslinker and sodium bicarbonate as porogen. The effect of various parameters such as crosslinker concentration, degree of neutralization of monomer acid, concentration of initiator have been evaluated. Water retention capacity of superabsorbents under varying loads was also examined. The drying behavior of polymers at 37°C was also studied. The gels showed sharp volume transition in solutions of divalent metal ions. The superabsorbents were also characterized by FTIR and TGA. 相似文献
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Pawel Nowak 《Reaction Kinetics and Catalysis Letters》1999,66(2):375-380
Kinetics of the liquid phase esterification of acrylic acid withn-octanol and 2-ethylhexanol catalyzed by sulfuric acid has been studied in an isothermal semibatch reactor. The reaction appears
to be second order. The kinetic parameters have been determined. 相似文献
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Ayman M. Atta Adel A.-H. Abdel-Rahman Ibrahi E. El Aassy Fadia Y. Ahmed Mohammed F. Hamza 《Journal of Dispersion Science and Technology》2013,34(1):84-94
Crosslinked acrylic acid (AA) acrylonitrile (AN) copolymer was prepared by suspension copolymerization in the presence of poly (vinyl alcohol) as suspending agent and N,N-methylenebisacrylamide (MBA) and divinylbenzene (DVB) as crosslinking agents. The molecular ratios between AN and AA was 95: 5 mol%. Different ratios 2, 5, and 10 wt% of crosslinkers was used. The nitrile group of the copolymer was converted to acrylamidoxime in the presence of hydroxylamine. Morphologies of the prepared resins were examined by scanning electron microscope (SEM). Recovery of uranium ions was investigated. The adsorption of uranium was occurred in nitric acid, hydrochloric acid and sulfuric acid solutions. Effect of pH, time of loading, type of acid, ratio, and type of crosslinker were investigated. Regeneration of eluted resins was determined. 相似文献
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The kinetics of polymerization of acrylic acid (AA) and methacrylamide (MAM) initiated by the redox system Mn3+ -ethoxyacetic acid (EAA) in aqueous sulphuric acid was studied at 35°C. The polymerization of both the monomers followed
the same mechanism, viz., initiation by the primary radical arising from the oxidation of EAA and termination by the Mn3+ ion. The rate coefficientsk
i
/k
0
andk
p
/k
i
were correlated to monomer and polymer radical reactivities, respectively. Acrylic acid was found to have higher monomer
and polymer radical reactivities than methacrylamide. 相似文献
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利用沉淀法制得焦磷酸盐与磷酸盐在浆状态下复配制备成复合催化剂,并用于催化乳酸脱水制丙烯酸.实验发现催化剂的组成对乳酸的转化率及丙烯酸的选择性有着重要的影响,当磷酸盐/焦磷酸盐质量比在30∶70~50∶50范围内,可以获得较高的乳酸的转化率和丙烯酸的选择性.催化反应条件如反应温度,乳酸进料浓度,液空速也被详细地进行了考察.此外,考察了该复合催化剂的稳定性.当催化剂连续运行56 h后,乳酸的转化率保持在96%以上,丙烯酸的选择性也高达57%.为了进一步揭示催化剂的结构与催化性能之间的关系,利用X射线粉末衍射、热重、扫描电镜和傅立叶红外等对催化剂进行了表征. 相似文献