低含量残留单体的中高分子量PVP K60合成研究

研究了引发体系、聚合机理和聚合工艺对聚乙烯基吡咯烷酮残留单体的影响,通过条件优化和特殊工艺得到残留单体低于USP32所规定的0.01%以下的PVP K60制品。     

PVP单体的合成研究进展及其应用

聚乙烯吡咯烷酮 ( PVP)是 N-乙烯基吡咯烷酮 ( NVP)经自由基聚合而成的一类高分子精细化学品。我国有关 PVP的研究工作分为 PVP单体 NVP的合成研究和 NVP聚合及其聚合物的应用。本文详细讨论了合成 NVP的催化剂种类、合成方法及工艺路线 ,简单介绍了 NVP合成研究的发展趋势。     

PVP(K-30)的合成工艺

以N-乙烯基吡咯烷酮（NVP）为原料,通过水溶液中聚合制备了医药级的聚乙烯吡咯烷酮PVP（K-30）。研究了引发剂、链转移剂和温度等对PVP相对分子质量和残留单体含量的影响,获得了一条适合生产实际的、操作条件温和的PVP（K-30）适宜合成工艺路线：NVP的质量分数为40%,聚合温度为75℃,引发剂为A和B复配,其中m（A）/m（NVP）和m（B）/m（NVP）分别为0.02和0.01,V（链转移剂D）/V（NVP单体溶液）为0.02,合成的PVP相对分子质量为29.8。     

可固化性环氧-丙烯酸酯聚合物压敏胶的研究

在丙烯酸酯类单体的乳液聚合过程中加入环氧树脂,可以制得可固化性乳液压敏胶.研究了环氧树脂含量、聚合物的玻璃化温度、聚合工艺等因素对压敏胶主要性能的影响,并通过对交联度的测量,确认了环氧树脂参与聚合交联的事实.实验得出:采用核-壳聚合工艺、当环氧树脂的含量为30%(wt)、共聚物玻璃化温度为243.15K时,制得的可固化性乳液压敏胶的初黏力为9号球,固化后对铝合金的粘接强度可达10MPa.     

光引发聚合阴离子型聚丙烯酰胺工艺及其产品絮凝效果的研究

采用光引发聚合方式,以丙烯酰胺(AM)和氢氧化钠(NaOH)为原料,采用前水解法合成阴离子型聚丙烯酰胺(PHP).研究了PHP光合成的影响因素,结果表明:采用光引发聚合的方式合成PHP是可行的.通过正交实验,确定了光引发聚合的影响因素顺序及最佳工艺参数;对最佳工艺合成的产品进行絮凝效果测试,其絮凝性能达到商品PHP的要求,对细粒度、富含高岭土的难沉降煤泥水絮凝沉淀效果明显.     

FEVE氟碳树脂氟含量影响因素探讨

通过对三氟氯乙烯-乙烯基酯氟碳树脂合成工艺的研究,分析检验树脂氟含量等性能指标,重点探讨了聚合反应中各组分和聚合工艺对树脂氟含量及性能的影响关系。     

超临界CO_2中合成的聚丙烯腈的性能研究

通过对超临界CO2 中合成的聚丙烯腈的相对分子质量、热稳定性、白度以及聚合物中微量单体含量等测试 ,研究了在超临界CO2 下所得聚丙烯腈的性能与合成工艺的关系。此外 ,通过纺丝实验 ,探索了聚合产物PAN的加工性能 ,得到了纤度为 3dtex左右、并具有一定强力的单孔纤维     

聚乙烯吡咯烷酮单体的合成工艺进展及其应用

聚乙烯吡咯烷酮(PVP)是由单体N-乙烯基吡咯烷酮(NVP)在适当的条件下聚合而成的一种高分子精细化学品。介绍了单体N-乙烯基吡咯烷酮的几种合成方法和工艺路线,对PVP在医药卫生、日用化工、食品饮料、纺织印染、涂料颜料等领域的应用进行了介绍。     

PVP/PAA共混水凝胶的制备及性能研究

以丙烯酸(AA)为单体,聚乙烯吡咯烷酮(PVP)为添加剂,通过引发剂引发自由基聚合制备了聚乙烯吡咯烷酮/聚丙烯酸(PAA)共混水凝胶,讨论了聚乙烯吡咯烷酮用量、反应温度、引发剂含量及交联剂含量等条件对合成凝胶影响,并研究了其溶胀行为。实验结果表明,在合成过程中,凝胶时间随PVP的含量增多而延长,且乳白色深度逐渐加深;随引发剂的增加,产生乳白色时间及凝胶时间缩短;一定范围内随温度升高可凝胶时间降低;交联剂的用量对凝胶时间无明显影响。在PVP/PAA共混水凝胶体系中,当PVP质量分数为0.6%,PAA质量分数为16.4%,引发剂的质量分数为0.024%,交联剂的质量分数为0.016%时,水凝胶的吸水性最佳,且随体系p H变化,酸性条件下吸水性较差,在碱性条件下吸水性较好;当在Na Cl溶液中溶胀时,水凝胶的吸水性能随盐离子浓度增大而下降且达到一定浓度后,水凝胶的吸水性能趋于稳定,盐离子对其影响微弱。PVP/PAA水凝胶的吸水效率高,且表现出很强的吸水能力,并且具有成本低廉,应用广泛等特点。     

高固含量丙烯酸酯无皂乳液的合成及性能研究

采用少量自制的可聚合乳化荆M-OP10,通过预乳化半连续滴加工艺成功合成了一种高稳定性、固含量达50%的甲基丙烯酸甲酯/丙烯酸丁酯/丙烯酸-2-乙基己酯[P(MMA/BA/EHA)]的无皂乳液.探讨了反应温度、反应时间、可聚合乳化荆用量等条件对合成的影响,并且对不同可聚合乳化剂用量的乳液及胶膜性能进行了研究.结果表明,当反应温度80℃、滴加时间1 h、保温时间1 h、可聚合乳化剂为单体质量分数0.4%时.制备的无皂乳液各项性能较好.     

The glass transition temperature of poly(N-vinyl pyrrolidone) by differential scanning calorimetry

Previously a wide range of values have been reported for the glass transition temperature, T_g, of poly(N-vinyl pyrrolidone), PVP, and it was suggested that lower values are due to variable uptakes of water caused by the hygroscopic nature of the polymer. Now it has been found that there are large variations in T_g, even in carefully dried specimens of PVP. Other factors found to influence T_g are residual monomer and the molecular weight of PVP. Polymers prepared by bulk polymerization, either by γ-irradiation or by heating with 2-azobisisobutyronitrile, have much lower values of T_g than dried ones prepared containing 30% water. The difference is mainly due to depression of T_g by residual monomer which, in the absence of water during polymerization, fails to react completely because of conversion to a glassy state. An unexplained observation is that even when all residual monomer has been removed, polymers prepared by bulk polymerization still have a lower T_g than would be expected from their molecular weight.     

非极性混合介质中分散聚合法制备聚乙烯基吡咯烷酮

以乙烯基吡咯烷酮(NVP)为单体,环己烷的混合溶剂为分散介质,AIBN为引发剂,SEBS为分散剂,采用分散聚合的方法制备了分散性能好、粒径为1μm左右、热稳定性较好的聚乙烯基吡咯烷酮。考察了单体含量、引发剂用量、分散剂用量对分散聚合反应的影响。结果表明,转化率和分子量均随单体含量增加而增大,随引发剂的量的增大而减小;且在单体含量为30%、AIBN的用量为0.5%,分散剂用量为10%时,所合成的聚合物分子量最大。     

丙烯酰胺水溶液聚合反应的研究

探讨了聚乙二醇作为分散剂时丙烯酰胺水溶液聚合体系中单体含量、还原剂用量对聚合物分子量的影响，并探讨了聚合时间与转化率、单体含量与聚合体系粘度之间的关系。结果表明，在保持聚合体系能够流动的前提下，单体含量可提高到２０％，聚合物的分子量可达３００万以上。     

聚乙烯吡咯烷酮的制备研究

研究了以过氧化氢—氨体系引发乙烯基吡咯烷酮水溶液的聚合过程,确定了聚乙烯吡咯烷酮的制备工艺条件。     

Effect of PVP in dispersion and seeded dispersion polymerizations

The outcome of seeded dispersion polymerizations of n‐butyl acrylate (BA) and styrene (St) in terms of the success of growing the seed particles without nucleating new particles or generating coagulum was found to be dependent on the seed type (poly[n‐butyl acrylate] [ PBA] or polystyrene [PSt]), the second‐stage monomer (BA or St), and the type of polyvinylpyrrolidone (PVP) stabilizer (PVP K30 or PVP K90). All seeds were first cleaned of excess stabilizer by medium replacement before the seeded polymerizations. In general, successful particle growth was achieved when the second‐stage polymerization employed PVP K30 (1 wt%) as the stabilizer. In contrast, nearly all reactions employing PVP K90 (1 wt%) as the second‐stage stabilizer resulted in the nucleation of a second crop of particles. These phenomena were further investigated by carrying out dispersion polymerizations using the supernatant obtained by separating the seeds from the second‐stage media (containing monomer). The results paralleled those in the seeding studies and were explained by the presence of small amounts of grafted PVP created in situ during the preparation of the seeds. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2721–2732, 2002     

Dispersion polymerization of methyl methacrylate: Effect of stabilizer concentration

In dispersion polymerizations of methyl methacrylate (MMA), little difference was found in the polymerization kinetics with varying stabilizer (PVP K‐30) concentration, indicating that in contrast to emulsion polymerization, the kinetics of these dispersion polymerizations are independent of the number of particles. Comparing MMA precipitation and dispersion polymerizations revealed that nuclei formation in the latter results from precipitation polymerization occurring in the continuous phase, which can contribute significantly to the kinetics, and especially to the molecular weight distributions. No change was found in the molecular weight distribution of the PVP during a dispersion polymerization, nor was there any measurable difference between using fresh and recycled stabilizer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

2‐Hydroxypropylmethacrylate based mono‐ and bifunctional gel beads prepared by suspension polymerization

Spherical and swellable gel beads in the size range 35–200 µm were prepared by suspension polymerization of 2‐hydroxypropylmethacrylate (HPMA). In the proposed method, a mixture of cyclohexanol and octanol was used as a diluent phase dispersed in an aqueous medium including poly(vinyl pyrrolidone) (PVP) as the stabilizer. The polymerization was initiated within the organic phase including the monomer and the crosslinker (ethylene glycol dimethacrylate) by an oil soluble initiator benzoyl peroxide. Spherical and swellable gel beads carrying both hydroxyl and carboxyl functional groups were also prepared by suspension copolymerization of HPMA and a water soluble comonomer (methacrylic acid). For this purpose, the suspension polymerization method proposed for HPMA was modified by using poly(vinyl alcohol) as a stabilizer instead of PVP. The effect of initiator concentration, polymerization temperature, monomer/diluent ratio, crosslinker concentration, stirring rate on yield, average size, size distribution, and carboxyl content of the HPMA based gel beads, were investigated. The swelling characteristics of the gel beads were defined. © 2000 Society of Chemical Industry     

Polymerization of butadiene in toluene with nickel (II) stearate-diethyl aluminum chloride catalyst. I. Catalytic behaviors

The polymerization of butadiene with nickel (II) stearate–Et₂AlCl catalyst has been studied in a batch reactor. The rate of polymerization is first order with respect to monomer and increases with the addition of water. In this system, no appreciable termination reaction has been found and the chain transfer to monomer dictates the molecular weight distribution of the polymer products. Molecular weight increases with conversion and water content. The cis-1,4 content was found to be a function of the extent of polymerization.