偏氯乙烯-丙烯腈悬浮共聚物的组成研究

研究了偏氯乙烯 丙烯腈 (VDC AN)悬浮共聚体系中AN的水溶性对单体相组成和树脂组成的影响 .结果表明 :由于AN部分地溶于水 ,使有机相AN的含量降低 ,导致共聚树脂的组成明显地不同于本体聚合模型的计算预测值 .为了准确地计算预测VDC AN共聚树脂的组成 ,本文假设溶于水的AN向有机相迁移的速度比聚合反应速度快得多 ,AN在两相的溶解分配近似为平衡态 .计算中先用描述AN在VDC/水系统中溶解分配的Marker式校正有机相AN的含量 ,然后根据校正后的AN含量用Mayo Lewis式计算预测VDC AN悬浮共聚物的组成 ,计算中有关的竞聚率值取自于文献中本体聚合的值 .计算结果与实验值一致     

AN/St悬浮共聚体系中AN在水/油两相间分配及其对共聚物组成的影响

研究了丙烯腈/苯乙烯(AN/St)悬浮共聚体系中AN在水/油两相间的分配及其对AN/St共聚物组成的影响.结果表明,AN分配于水/油两相间,使油相AN的含量低于相同单体配料比的本体聚合,导致生成的AN/St共聚物组成偏离本体共聚.为了准确预测进而控制AN/St悬浮共聚物的组成,提出了在考虑AN相分配的基础上计算AN/St悬浮共聚物组成的模型.计算结果与实验值一致,计算中用到的油相实际竞聚率与本体聚合相同,但该悬浮聚合的表观竞聚率随水/油比的变化而发生较大改变.     

在α-甲基苯乙烯二聚体调节作用下的苯乙烯-丙烯腈乳液共聚

<正> 由于苯乙烯(St)和丙烯腈(AN)竞聚率的差异,在乳液共聚中所得产物为组成不均匀的共聚物,因此一般在反应后期通过复杂计算和实验验证补加消耗快的单体,或采用回收大量单体等方法得到组成均匀的共聚物。St-AN乳液共聚物的分子量较大,产物不     

聚(苯乙烯-丙烯酸)-氯化铜配合物催化引发丙烯腈聚合的研究

将聚(苯乙烯-丙烯酸)(PSAA)(Mw=3500)与氯化铜在异丙醇溶液中反应得到一种配位聚合物膜聚(苯乙烯-丙烯酸)-氯化铜(PSAA-Cu(Ⅱ)).研究丙烯腈(AN)在该配位聚合物膜、HSO3-和水体系(温度为55℃)催化引发作用下的聚合反应历程.AN在上述的催化引发体系中是按照自由基加聚反应历程进行聚合的,PSAA-Cu(Ⅱ)在催化引发体系中起着催化剂的配位催化作用.讨论了温度、Na2SO3浓度、AN浓度和PSAA-Cu(Ⅱ)膜用量对聚合速率、诱导时间的影响.实验结果表明,配合物PSAA-Cu(Ⅱ)膜催化引发AN聚合的诱导期为128s,反应24h后PAN产率为75.6%,Mw=2.18×104和Mn=1.12×104,多分散性系数为1.95.     

颗粒内受限聚合法制备PP/POE/PS合金

以等规聚丙烯/乙烯-辛烯共聚物(PP/POE)合金颗粒为扩散基体, 苯乙烯(St)为扩散单体, 利用颗粒内受限聚合法制备了PP/POE/PS三元合金. 结果表明, 对于POE质量分数为20%~40%的PP/POE合金颗粒, St均可扩散至直径为4 mm的颗粒中心部位, 在POE非晶相中生成相尺寸为几十至几百纳米的PS球. 在PP/POE合金颗粒的不同部位, 因POE相尺寸及单体的吸附量不同, 生成的PS相尺寸也不同, 在颗粒中心部位生成的PS球最小. 研究了St在PP/POE(质量比80: 20)颗粒中的扩散-聚合行为, 结果表明, St在合金颗粒中的扩散速率和扩散饱和值远大于在纯PP颗粒中的扩散速率和饱和值, 这主要是因为PP/POE合金颗粒中的非晶POE相有利于扩散. 改变单体投料量可以获得具有不同PS含量的PP/POE/PS三元合金. 结晶性能研究结果表明, PS在非晶POE相中的优先分布会使POE相体积增大, 从而使PP的结晶温度和熔融温度降低. 随着PS量的进一步增大, 分布在PP中的PS对PP有结晶成核作用.     

用新型发泡剂--氢化混合稀土制备泡沫铝的研究

研究了混合稀土的氢化工艺和以其作为一种新型发泡剂制备泡沫铝的方法与机制。实验采用熔体发泡法制备闭孔泡沫铝，并与氢化钛(TiH2)作发泡剂制备泡沫铝进行对比实验。结果表明：混合稀土氢化物(REHx)发泡剂的特点是起始发泡温度高，能较显著的延缓气体的释放速率，促使发泡均匀化。经过发泡工艺的优化，以其制备的泡沫铝与用氢化钛(TiH2)做发泡剂相比较，在相同孔隙率条件下，泡沫铝的抗压缩强度有明显提高。     

在超声辐照作用下聚氧化乙烯和丙烯腈嵌段共聚的研究

本文研究了聚氧化乙烯(PEO)和丙烯腈(AN)在水溶液中的超声共聚。共聚速率和AN浓度成正比,存在AN浓度最低限。PEO的降解速率常数越大,它所共聚的AN量越大,表明AN的聚合是由PEO降解生成的大自由基引发生成的。通过元素分析和IR测定证明产物为PEO-AN共聚物。通过POM、TEM、DSC和WAXD测定证实共聚物为结晶嵌段共聚物。     

苯乙烯-甲基丙烯酸甲酯悬浮-乳液复合聚合过程中聚合物复合粒子组成的变化

采用苯乙烯(St)悬浮聚合过程中滴加甲基丙烯酸甲酯(MMA)乳液聚合组分,悬浮乳液复合聚合(SECP)方法,制备大粒径聚苯乙烯聚甲基丙烯酸甲酯(PS- PMMA)复合粒子.采用FTIR、1H- NMR、13C- NMR分析方法,研究SECP各个时期复合粒子中MMA- St链节摩尔比,发现悬浮粒子中MMA St链节摩尔比逐渐增大,而PMMA乳胶粒子中逐渐减少,表明悬浮相和乳液相间存在物质传递过程.悬浮粒子中MMA链节质量与MMA总投料质量比主要由乳胶粒子生成速率和乳胶粒子向悬浮粒子凝聚速率决定.最终得到的复合粒子除含PS和PMMA均聚物外,还含少量MMA-St共聚物.     

SAN共聚物组成对PVC/ABS共混物相容性的影响

采用乳液聚合技术通过改变共聚单体的投料比(St/AN)合成了一系列不同AN结合量的ABS接枝共聚物粉料和SAN共聚物.将其与聚氯乙烯(PVC)和邻苯二甲酸二辛酯(DOP)熔融共混分别制得了PVC/ABS、PVC/SAN、PVC/ABS/DOP和PVC/SAN/DOP共混物,利用SEM、TEM和动态力学粘弹谱仪(DMA)对共混物的相容性和相结构进行了表征.结果发现,在PVC/ABS共混体系中,尽管改变接枝SAN共聚物的AN结合量,PVC和SAN共聚物均为不相容体系;在该共混物中引入增塑剂DOP后,虽然当SAN共聚物AN结合量小于23.4 wt%时,共混物在室温以上只存在一个tanδ峰,但形态结构研究结果表明共混物仍为不相容体系,共混物的相区尺寸明显地依赖于SAN共聚物中的AN结合量,当AN结合量为23.4 wt%时相区尺寸最小.     

低相对分子质量苯乙烯-马来酸酐交替共聚物的合成

将引发剂偶氮二异丁腈(AIBN)、共聚单体苯乙烯(St)和马来酸酐(MA)溶解于甲苯中,采用沉淀聚合法合成苯乙烯-马来酸酐共聚物(SMA).分别研究了反应温度、引发剂用量、反应时间、单体配比和单体浓度对聚合物得率和酸酐含量的影响.采用正交实验确定最优反应条件为:单体浓度20%,单体物质的量比为1∶1,引发剂用量为0.60%,反应温度为86℃,反应时间2h,产物得率为86.86%,酸酐含量为50.28%.并利用傅里叶变换红外光谱(FTIR)、核磁共振碳谱(~(13)C NMR)、凝胶渗透色谱(GPC)和热分析法分别研究聚合物的分子结构、相对分子质量及相对分子质量分布和热稳定性.结果表明产物是苯乙烯-马来酸酐交替共聚物,相对分子质量分布较窄,具有良好的热稳定性.     

Sorption kinetics of 1-fluoro-1,1-dichloroethane in vinylidene chloride-acrylonitrile-styrene terpolymer

The sorption kinetics of liquid 1-fluoro-1,1-dichloroethane (HCFC-141b) and its vapor in vinylidene chloride (VDC)-acrylonitrile (AN)-styrene (St) terpolymers were investigated by weight gain method. It was found that the sequence of the effect of monomer unit on the barrier property for HCFC-141b is AN>VDC>St at the same molar content. The diffusion mechanism of HCFC-141b in VDC-AN-St terpolymer depends on the glass transition temperature (T_g) of VDC terpolymers, sorption temperature, vapor pressure and so on. For Fickian diffusion, the diffusivity (D) is exponential function of vapor pressure at the same temperature. A quantitative relationship between D in terms of HCFC-141b in VDC-AN-St terpolymer with composition VDC/AN/St=55.7/12.9/31.4 (wt), temperature and activity was obtained, and the activation energy of diffusion is 37.68 KJ/mol.     

Core-shell emulsion copolymerization of styrene and acrylonitrile on polystyrene seed particles

Seeded emulsion copolymerization of an azeotropic composition of styrene (St) and an acrylinitrile (AN) comonomer mixture in polystyrene (PS) seed at different polymerization temperature of 55–75°C were investigated. The kinetic data showed a transition temperature at 65°C, above which the activation energy of polymerization is low, 6.1 Kcal/mol, compared with 9.8 Kcal/mol below it. The particle-size results and thin layer chromatographic (TLC) data showed two types of particle of different composition and morphology in the final latex system: a smaller size of (St–AN) copolymer and a larger size of core-PS and (St–AN) copolymer shell, with a zone of PS grafted (St–AN) copolymer in between. Various polymerization parameters, that is emulsifier concentration, type of seed particle and its size, and monomer/polymer ratio, were studied and their effects on particle size and particle morphology were examined. The percent of grafted core-PS was 10% below a polymerization temperature of 65°C and 40% above that temperature. By adjusting the size and number of the seed particles, monomer-polymer ratio, and emulsifier concentration conditions were established in which a final copolymer latex with “perfect” core-shell morphology was achieved.     

An experimental study on saturation swelling of styrene–acryronitrile copolymer particles with styrene and acrylonitrile monomers

The saturation swelling behavior of styrene and acrylonitrile (SAN) copolymer particles with a styrene (St) and acrylonitrile (AN) comonomer mixture was investigated experimentally. The effects of the copolymer composition and the compositional inhomogeneity in SAN Copolymer particles on their swelling behavior were examined. The experimental results show that both the copolymer composition and the compositional inhomogeneity in SAN copolymer particles have little or no influence on the swellability of SAN copolymer particles with a St and AN comonomer mixture, as long as the weight fraction of AN monomer units in SAN copolymer particles is less than a certain value between 0.6 and 0.8. With increasing AN content in the copolymer particles beyond this value, however, the swellability of SAN copolymer particles gradually decreases. Semiempirical equations are proposed, which correlate the saturation concentration of each monomer in SAN copolymer particles as a function of the comonomer composition in the monomer droplets and the overall copolymer composition in SAN copolymer particles. © 1994 John Wiley & Sons, Inc.     

分散共聚法制备窄分布P(St-co-nBA)微球

用分散共聚法制得窄分布苯乙烯(St)和丙烯酸正丁酯(nBA)的共聚物微球.采用1H-NMR、DSC、FTIR、SEM、LS等对共聚物的结构、形态、性能进行表征,考察了初始单体配比、温度、稳定剂浓度、分散介质极性、引发剂对微球粒径、粒径分布及转化率的影响.实验结果表明,初始单体比nBA/St增大,微球粒径增大,分布变宽,...     

耐热聚氯乙烯的耐热机理研究

用悬浮聚合方法制得了氯乙烯 N 苯基马来酰亚胺 ( 丙烯腈 )共聚物 ,研究了该共聚物的维卡软化点、玻璃化温度、动态力学行为以及形态结构 .发现当耐热组分达到一定含量时 ,耐热性能的增加幅度发生变化、出现两个动态力学内耗峰、形态上出现双连续相结构 .基于这些实验现象 ,提出了“刚性有效网架”可以使耐热性能大幅度提高的观点 ,并探讨了耐热机理 ,给出了物理模型 .讨论了相容性对“刚性有效网架”形成的影响     

SUSPENSION-SWELLING GRAFT COPOLYMERIZATION——SYNTHESIS OF ACS RESINS*

Acrylonitrile (AN)-chlorinated polyethylene (CPE)-styrene (St) (ACS) terpolymer was synthesized by suspension-swelling graft copolymerization method, in which two key factors such as dispersing system and time were studied. Highly effective comples dispersing system was chosen and determined, and two-layer protection model was put forward to clarify the stable effect mechanism Varying the swelling time of CPE in AN and St monomer mixture, some results such as grafting effect, particle characteristics, rubber particle morphology and its size distribution, and properties of ACS resins were investigated , thus the optimum swelling time was proposed.     

Effects of acrylonitrile water solubility on limiting conversion and copolymer composition in suspension polymerization

The effects of acrylonitrile (AN) water solubility on the limiting conversion and copolymer composition of the AN and AN/vinylidene chloride (VDC) suspension polymerization were investigated. It was found that AN dissolved in aqueous phase does not transfer back to oil phase in AN suspension homopolymerization but partially does in AN/VDC suspension copolymerization, and thus the limiting conversion is lowered and decreases with water/oil ratio increasing in both AN and AN/VDC suspension polymerization. For the continuous transport of AN in aqueous phase to oil phase during suspension polymerization, the composition distribution of AN/VDC copolymer prepared by suspension polymerization is narrower than that by bulk polymerization. The calculated composition of AN/VDC suspension copolymer with considering AN water solubility is consistent with the experimental data.     

碳酸乙烯酯溶剂中丙烯腈的聚合行为

以碳酸乙烯酯为溶剂,偶氮二异丁腈（AIBN）为引发剂,采用溶液自由基聚合的方法对丙烯腈(AN)均聚合、丙烯腈/衣康酸(AN/IA)二元共聚及丙烯腈/衣康酸/丙烯酸甲酯(AN/IA/MA)三元共聚合进行了研究。 考察了反应温度对丙烯腈均聚合,以及聚合单体浓度对丙烯腈共聚合的影响,在60 ℃合成了相对分子质量高于4.5×105、单体转化率高于85%的丙烯腈均聚物及共聚物。 采用正十二烷基硫醇（DDT）和甲酰基哌啶（FP）作为链转移剂,对AN均聚物、AN/IA及AN/IA/MA共聚物的相对分子质量进行调控,考察了链转移剂浓度对聚合物相对分子质量和单体转化率的影响。 结果表明,w(DDT)为0.25%时（以单体质量计）,聚合物相对分子质量可有效调节到1×105,而单体转化率保持在80%以上。     

氯乙烯-N-苯基马来酰亚胺(-丙烯腈)悬浮共聚物的耐热性能

用玻璃化转变前后储能模量的变化、储能模量的变化速率以及内耗的大小等参数来考察氯乙烯(VC) N 苯基马来酰亚胺 (PMI)以及氯乙烯 N 苯基马来酰亚胺 丙烯腈 (AN)悬浮共聚物的耐热性能 ,辅以维卡软化点测定进行比较 .用动态力学分析方法的研究结果表明 ,共聚物发生玻璃化转变时 ,储能模量随温度的最大变化速率的绝对值越小 ,则其耐热性能越好     

SYNTHESIS OF STYRENIC TONER PARTICLES BY SPG EMULSIFICATION TECHNIQUE

This research studied the initiator efficiency for producing polymeric particles of poly(styrene-co-methylmethacrylate) copolymers by a Shirasu porous glass membrane (SPG) emulsification technique followed by suspensioncopolymerization. BPO, ADVN, and AIBN were used as initiators and we found that BPO is the most suitable initiator.Copolymers for various feed ratios of styrene/methyl methacrylate were thus synthesized by benzoyl peroxide, and theircopolymer particle size, molecular weight distribution and particle size distribution were characterized. Then n-BMA or 2-EHMA was added as the third monomer to decrease the terpolymer glass transition temperature. This article describes thepreparation technique, recipes and polymerization conditions for producing both copolymer and terpolymer panicles, particlesize changes, the corresponding particle morphologies and glass transition temperatures.