异戊烷溶剂体系合成稀土异戊橡胶聚合工艺的研究

进行了异戊烷溶剂体系合成稀土异戊橡胶聚合工艺的研究。考察了催化剂用量、温度、单体质量浓度和时间对异戊二烯（IP）聚合反应和聚合物结构的影响,确定了异戊烷溶剂体系聚合工艺条件：每克IP催化剂用量（1．5～2．0）×10-8mol,聚合温度50℃,p（IP）=10g／dL,聚合时间3h。制备的异戊烷溶剂体系的稀土畀戊橡胶产品质量与己烷溶剂体系的相当,达到了国外同类产品水平。     

非稳态体系合成聚丙烯酰胺

主要研究了非稳态体系中合成聚丙烯酰胺（PAM）。非稳态体系即在油包水的环境下,通过剧烈搅拌使单体水溶液在油相中分散成小液滴进行自由基聚合,可有效地提高体系的散热效率,同时可大幅提高聚合物的固体质量分数。非稳态体系停止搅拌后,聚合物颗粒与油相可以自行分层,过滤、洗涤后就可以得到较纯的PAM。实验以聚二甲基硅氧烷为油相,探究了丙烯酰胺单体在非稳态体系中,不同聚合温度、单体水溶液浓度和pH的聚合效果,以及油水比、搅拌速度对体系内聚合物的固体质量分数、粒径的影响,并用游标卡尺精确测量颗粒的粒径。同时,用溴化法和一点法分别测量反应转化率和分子量,采用红外透射光谱和核磁共振氢谱的表征手段,对非稳态体系聚合的产品进行分析。结果表明,非稳态体系在4：3的油水比和大于300r/min的转速下,可合成转化率超过99%、溶解性优良的高分子量的聚丙烯酰胺产品颗粒。     

聚氨酯-丙烯酸酯复合乳液体系及其制备

介绍了化学共聚聚氨酯-丙烯酸酯(PUA)复合乳液体系及其制备工艺,将体系分成非交联型、合成交联型、成膜交联型和互穿网络型四种类型,将制备工艺分成种子乳液法聚合法、原位聚合法和溶液聚合相转化法三种方法,以此综述了PUA复合乳液的制备进展,指出原位法与相转化法制备交联型PUA复合乳液将成为今后的发展方向。     

复合引发体系制备聚丙烯酸钠

采用水溶液聚合,使用了由氧化还原引发体系和偶氮类引发剂组成的一种复合引发体系制备高分子量聚丙烯酸钠。考察了引发剂用量、反应温度、单体中和度、单体浓度对分子量的影响,并对复合引发体系与氧化还原引发体系进行了对比,得出优化条件:各引发剂用量:M用量=0.48‰,K2S2O8用量=0.2‰,NaHSO3用量=0.2‰,脲素用量=5‰,乙二胺用量=5‰;聚合工艺条件为:聚合温度25℃,单体中和度80%,单体浓度25%,聚丙烯酸钠分子量达到1470万。     

聚氯乙烯树脂热稳定性探讨

通过对聚氯乙烯降解机理的分析,提出在聚合体系中添加助剂并控制单体质量,改进工艺措施,提高PVC树脂制品的热稳定性。     

微量离子对凝胶注模成型丙烯酰胺聚合体系凝胶点的影响

在凝胶注模成型工艺中，无机离子的存在对丙烯酰胺聚合体系的凝胶点有着不同程度的影响，Fe^2 ,Cu^2 ,Al^3 ,Ca^2 等无机离子常常以微量杂质的形式存在于陶瓷粉体中，本工作主要研究上述无机离子的微量添加对该聚合体系凝胶点的影响，总结了它们的影响规律，深入探讨了其影响机制，从而为控制凝胶注模成型工艺参数提供了必要的参考依据，实验研究发现，微量Fe^2 ,Cu^2 对体系聚俣有明显的加速作用，从而使凝胶点变短；Al^3 也会使聚合加速，但效果并不显著；Ca^2 则对体系具有阻聚作用。     

通过氧化还原引发体系制备水性含氟乳液

以壬基酚聚氧乙烯醚和全氟辛酸铵为复合乳化体系，氧化还原体系为引发剂，在室温下制备水性含氟乳液。系统地研究了单体配比和合成工艺如聚合温度、聚合时间对单体总转化率、含氟量、乳液性状、黏度、粒径及稳定性等主要性能的影响。通过红外光谱、GPC等手段对水性含氟聚合物的分子结构进行了表征。     

复合调节体系对聚丁二烯反应动力学及微观结构的影响

以正丁基锂为引发剂、环己烷为溶剂,采用阴离子聚合工艺进行了丁二烯的均聚.考察了不同复合结构调节体系(SDBS/THF,SDBS/TMEDA)对聚合反应动力学和聚合物微观结构(1,2结构含量)的影响.结果表明,采用复合结构调节体系可加快聚合反应,缩短聚合时间,同时可在较大范围内调节聚合物的1,2结构含量.     

负离子双锂引发剂体系的研究Ⅱ.双锂引发剂-异戊二烯聚合体系的缔合

讨论了双锂引发剂－异戊二烯聚合体系的缔合模型,提出了分子内缔合是双锂引发剂聚合体系的重要特点。并用这种模型分析了造成双锂引发异戊二烯聚合产物相对分子质量分布为双峰并有小分子拖尾现象的原因,解释了双锂引发体系较单锂引发体系聚合速度慢的实验结果     

提高PVC国产30m^3聚合釜生产能力及产品质量的对策

采用全自动化密闭操作,先进的防粘釜技术及工艺,热水进料,反应中间连续注水,使用复合引发剂,聚合釜循环水处理一夹套清洗,是提高国产３０ｍ＾３聚合釜生产能力的好方法。但国产３０ｍ＾３聚合釜釜壁粗糙,内冷管多,极易粘釜。如何在基本不影响现有生产的基础上３０ｍ＾３聚合釜的传热系数,以利于全自动化操作是提高生产能力工作中的难点。分散剂、引发剂及秒种助剂集中配制,使用高效无毒终止剂,改良聚合釜的搅拌体系,调整     

高硅含量四甲基甲乙烯基环四硅氧烷改性丙烯酸酯乳液的聚合稳定性

以四甲基四乙烯基环四硅氧烷(Vi-D4)为有机硅单体,在乳液体系中开环聚合得到有机硅中间体,采用种子乳液聚合工艺,与丙烯酸单体共聚得到高硅含量的硅丙乳液。研究了体系的pH、加料方式、乳化剂的用量、引发剂的用量对乳液聚合稳定性的影响,发现Vi-D4在pH=3下开环聚合,引发剂用量为单体总量的0.4%,且其配比为3∶2,乳化剂的用量为3%,控制丙烯酸有机硅中间体的滴加时间分别为2 h和3 h制得的乳液稳定性高。     

梯度苯丙乳液的合成

以苯乙烯(St)和丙烯酸丁酯(BA)为主要核单体,甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为主要壳单体,甲基丙烯酸(MAA)和甲基丙烯酸羟丙酯(HPMA)为功能性单体,采用梯度乳液聚合法制备了硬核软壳型苯丙乳液。考察了聚合工艺,乳化剂的配比及含量,引发剂浓度,反应温度以及功能性单体含量对乳液聚合过程及性能的影响。结果表明:乳化剂占单体总量的1%,DSB/OP-10的质量比为2∶1,引发剂占单体总量的0.5%,反应温度为80℃,功能性单体含量为4%时,聚合稳定,凝胶量少,乳液性能优异,且采用梯度乳液聚合方式可有效降低乳液的最低成膜温度。通过红外光谱测定了苯丙共聚物的结构组成,透射电镜(TEM)对粒子结构进行分析,验证了其梯度结构形态。     

Some peculiar features of radiation grafting of monomers of various structures and reactivities onto polyolefins

Some peculiar features were studied for radiation grafting of monomers of various structures and reactivities in radical polymerization onto polyolefins (polyethylene and polypropylene). From the point of view of the kinetics and mechanism of grafting, the monomers are divided into two classes: The first class includes all monomers active in radical polymerization. When irradiated together with the polymeric matrix, they are grafted onto it as long polymeric chains and parallel to this occurs homopolymerization. The second class includes nonactive or slightly active monomers for radical polymerization. They are characterized by the formation of single units or short grafted chains. The possibility to add nonactive monomers with high radiation chemical yields was demonstrated. A mechanism was proposed to explain high radiation yields for a number of nonactive monomers by transferring the radical state along and/or between polymer macromolecules. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 711–718, 2000     

有机硅-丙烯酸酯乳液聚合稳定性研究

采用种子乳液聚合工艺,以过硫酸铵为引发剂、十二烷基二苯醚二磺酸钠(DOWFAX2A1)/辛基酚聚氧乙烯(40)醚(TRIONX-405)为复合乳化剂合成了乙烯基 三(2 甲氧基乙氧基)硅烷(A-172)改性丙烯酸酯聚合物。研究了单体加入方式、乳化剂用量、聚合温度、pH值等对聚合稳定性的影响。结果表明,当总乳化剂质量分数为3 0%、聚合温度为75～80℃、pH=6 5～7 5时,采用净单体滴加法制备聚合物的聚合过程稳定性较好;增加A-172用量,聚合稳定性降低。     

乳液聚合制备自交联纸塑复合胶粘剂的研究

以丙烯酸和甲基丙烯酸 - 2 -羟乙酯为官能单体 ,采用半连续种子乳液聚合法制备自交联聚丙烯酸酯类乳液型纸塑复合胶粘剂 ,研究了乳液聚合工艺 ,着重讨论了单体的选择与配比、聚合温度、聚合时间、氧化还原引发体系中氧化剂与还原剂的比例、乳化剂的用量等因素对聚合反应及纸塑复合胶粘剂性能的影响     

Well-defined organic-inorganic hybrid benzoxazine monomers based on cyclotriphosphazene: Synthesis, properties of the monomers and polybenzoxazines

Well-defined organic-inorganic hybrid benzoxazine monomers based on cyclotriphosphazene (CP) cores have been synthesized. Theses monomers possessed controllable number of organic benzoxazine moieties and biphenyl groups distributed on the inorganic ring of CP. Corresponding ring-opening polymerization under heat led to highly cross-linked polymers with different number of crosslinking sites. The ring-opening polymerization behaviors of the new benzoxazine monomers were investigated by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA). The results indicated that the polymerization activity of the monomers depended on the number of benzoxazine moiety of corresponding monomers. Those monomers with more benzoxazine moieties resulted in higher polymerization rate. Due to the high crosslinking nature with rigid and stable inorganic CP ring and biphenyl groups in the networks, the resulted polybenzoxazines from the monomers showed excellent thermal stability, mechanic property and humidity resistance.     

Solid-state polymerization of derivatives of 2,4,6-octatriyne: 9. Topochemical reactions of monomers with conjugated triple bonds

The solid-state polymerization of monomers with three conjugated triple bonds gives rise to polymer single crystals. The lattice parameters of the polymers from 2,4,6-octatriyne-1,8-diol and 2,4,6-octatriyne-1,8-diol-bis(phenyl urethane) were determined. Based on these data and considering the mechanical properties and dichroism of the polymer crystals, it is concluded that polymerization proceeds according to a 1,4-addition to the triple bond system of the monomers. Only two of the three triple bonds of the monomers are affected by polymerization to form the polymer backbone of regularly alternating double, single and triple bonds. The residual triple bond is regularly arranged in the all-trans position as part of the substituents. The kinetics of the thermal and photopolymerization of these monomers are quite similar to those of the corresponding diynes. The activation energy of thermal polymerization was found to be 23 kcal/mol as compared to 19 kcal/mol for comparable diynes. The long wavelength limit of photosensitivity was found to be at about 380 nm as compared to 330 nm for diynes.     

Room temperature-initiated and self-heating copolymerization of acrylonitrile with vinyl acetate

A novel polymerization method [Ruckenstein and Li, Polymer Bull., 37, 43 (1996)]—room temperature-initiated, self-heating polymerization—was applied to both bulk and concentrated emulsion copolymerization of acrylonitrile (AN) with vinyl acetate (VAc). A redox system was employed as an initiator, with the oxidant dissolved in the monomers and the reductants (two reductants were employed) in the aqueous phase. In the bulk polymerization, the oxidant (cumene hydroperoxide) was dissolved in the mixture of monomers, and the two reductants (sodium metabisulfite and ferrous sulfate) were introduced as an aqueous solution. In the concentrated emulsion polymerization, a mixture of the monomers containing dissolved oxidant was first used as the dispersed phase of a concentrated emulsion in water, and the aqueous solution of reductants was subsequently added to the concentrated emulsion. In both cases, the polymerization started at room temperature, just after the reductants were introduced. Because the reactor was insulated, the heat generated by the reaction was mostly used to accelerate the polymerization, which reached a high conversion in 30 min. The effects of various parameters on the polymerization were investigated. Optimum values were found for the volume fraction of the dispersed phase, for the wt ratios of the two reductants and of the oxidant to reductants, and for the surfactant and reductant concentrations. One concludes that the concentrated emulsion polymerization method is particularly suitable for the room temperature-initiated, self-heating polymerization. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 999–1011, 1998     

Theoretical investigation on the polyaddition of A2 and CB2 monomers with non-equal reactivity

Taking account of the difference of reactivities between C and B group, the evolution of the monomers and the various structural units formed from the polyaddition of A₂ and CB₂ monomers was investigated by the kinetic mechanism. The calculated results theoretically explain the experimental data observed in our previous works very well, if the reactivity ratio of C to B groups is 200. The critical conversion of gelation for the A₂ + CB₂ type polymerization depends on the reactivity ratio. The lower the ratio, the earlier the gelation appears. Compared with the A₂ + B₃ type polymerization, the disappearance of gelation for the A₂ + CB₂ type polymerization should attribute to the much higher reactivity of C group than that of B one. The analytical expression of the degree of branching was derived as well. If the reactivity of C group is much higher than that of B group and the substitution effect is neglected, the value of the degree of branching for the hyperbranched polymers obtained is equal to the value of conversion of B groups and it may exceed 0.5, with the feed ratio of monomers varying from 1 to 3/2.     

水溶性单体类型对BA-MMA-St微皂乳液聚合的影响

通过与水溶性单体、甲基丙烯酸（MAA）、丙烯酸（AA）、N-羟甲基丙烯酰胺（N-MA）、丙烯酰胺（AM）共聚，实现了BA-MMA-St的微皂乳液聚合。考察了水溶性单体（羧酸类单体、非离子水溶性单体）对微皂乳液聚合稳定性和化学稳定性的影响。实验结果表明：为了使水溶性单体键合在乳胶粒表面，实现乳胶粒的稳定化，其亲水性参数I／O应为3～5，水溶性单体还必须具有良好的聚合稳定性及与主单体良好的共聚性。