丙烯腈共聚物序列分布的Monte Carlo模拟

通过Monte Carlo方法，对不同共聚单体的聚丙烯腈组成进行了模拟。通过比较．与文献中提供的实验结果基本一致。同时模拟了衣康酸(1A)、丙烯酸(AA)、甲基丙烯酸(MAA)分别与丙烯腈(AN)在不同配比下共聚物的序列分布，结果表明：在Monte Carlo模型中，可以通过控制单体的配比来控制序列分布，而在实际的合成中，要获得均匀的序列结构，就可以通过降低第二单体投料比法或滴加单体法来实现。     

连续水相沉淀聚合中聚丙烯腈颗粒形态的影响因素

研究了中试规模的连续搅拌釜内丙烯腈/丙烯酸甲酯/衣康酸(AN/MA/IA)三元水相沉淀聚合，考察了共聚序列结构、共聚单体用量、引发剂用量和反应pH值对聚丙烯腈颗粒形态的影响。研究发现：共聚物序列结构改善、均匀性变好，可以提高颗粒稳定性，减小颗粒粒径及分布指数，增加颗粒密实度，降低沉降值；适当增加共聚物IA组分、提高引发剂用量、提高pH值，可以提高共聚物的颗粒稳定性，改善颗粒形态。     

丙烯腈/衣康酸在DMSO/H2O中的共聚物结构模拟

采用丙烯腈(AN)与衣康酸(IA)在DMSO/H2O中共聚,计算了两种反应单体的竞聚率:rAN=0.405,rIA=2.946。采用计算机模拟,进一步研究了聚(丙烯腈 co 衣康酸)共聚物的分子结构与转化率的关系。给定自由基共聚反应的初始条件,还模拟了丙烯腈与衣康酸二元共聚物序列分布。随着转化率不同,共聚物中衣康酸的组成相差较大,反应初期大多数的IA共聚单体参加反应,特别是在少量衣康酸作共聚单体时,随着衣康酸的加入,丙烯腈的平均序列长度快速降低。     

过硫酸铵引发丙烯腈／衣康酸铵的共聚合工艺研究

选择衣康酸铵[(NH4)2IA)]作为共聚单体,以过硫酸铵[(NH4)2S2O8]为引发剂,采用水相沉淀聚合工艺合成高分子质量的丙烯腈／衣康酸镀[AN／(NH4)2IA)]共聚物。研究了引发剂浓度、单体浓度、单体配比、聚合温度和聚合时间对共聚反应的影响。结果表明:该体系的聚合反应速率较快,且制得了粘均分子质量高达(38-75)×104的AN／(NH4)2IA共聚物。     

不同共聚单体与丙烯腈的共聚合及其表征

采用四种共聚单体衣康酸(IA)、丙烯酸甲酯(MA)、丙烯酰胺(AM)、甲基丙烯酸甲酯(MMA)分别与丙烯腈(AN)进行自由基溶液共聚合,讨论了不同共聚单体对聚合反应动力学及所得纺丝原液的粘度的影响,对聚合物的热性能进行了DSC分析,考察了不同共聚单体对聚丙烯腈原丝热性能的影响。结果表明:AN/IA体系随IA含量的增加其反应速率明显下降;与其它单体相比AM更可能有效地降低聚丙烯腈原丝的预氧化温度,缓和放热,而衣康酸次之。同时,IA含量过大,会导致原丝预氧化时的降解。     

离子液体中丙烯腈三元共聚的研究

采用离子液体1-丁基-3-甲基咪唑四氟硼酸盐([BMIM]BF4)为溶剂,进行了丙烯腈(AN)、丙烯酸甲酯(MA)、衣康酸(ITA)的自由基三元共聚反应的研究。讨论了总单体浓度、引发剂含量、聚合时间、MA含量、ITA含量对共聚物相对分子质量和转化率的影响。结果表明:以离子液体[BMIM]BF4为溶剂,AN、MA和ITA可发生三元共聚,聚合物相对分子质量可达10万以上;且MA的含量可以很低直至为0,对聚合物相对分子质量影响不大;以离子液体为溶剂的共聚物的化学结构与以NaSCN水溶液为溶剂的聚合物的结构相似。     

氯乙烯/丙烯腈共聚物组成和溶解性及影响因素

以十二烷基硫酸钠(SDS)为乳化剂,过硫酸钾(KPS)和亚硫酸氢钠(SBS)为氧化还原引发体系,通过乳液聚合方法制备了氯乙烯(VC)/丙烯腈(AN)共聚物.采用氧瓶燃烧法测定了共聚物的氯含量,并计算了共聚组成,通过抽提测定了共聚物在丙酮中的溶解性.考察了一步法聚合过程中共聚物组成及溶解性随聚合时间的变化,研究了初始单体投料比、引发剂用量、聚合温度等工艺条件对共聚物组成及溶解性的影响.结果表明,由于AN活性高,VC/AN共聚组成和溶解性随聚合时间变化较大;共聚物在丙酮中的溶解性与共聚组成相关,受初始单体投料比影响最大,在VC/AN投料物质的量比为7.6:1时可以获得在丙酮中全部溶解的共聚物.     

三元共聚物P(IA/MA/AMPS)的合成及阻垢性能评价

以衣康酸(IA)、马来酸(MA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为单体,以过硫酸铵为引发剂,以水为溶剂,通过自由基聚合合成了一种新型的三元共聚物,探讨了单体配比、聚合温度、引发剂用量、聚合时间等合成条件对阻垢性能的影响,确定了最佳的合成条件为:单体配比n(IA)∶n(MA)∶n(AMPS)=1∶1∶1,聚合温度80℃,引发剂占单体质量分数的5%,聚合时间2h;用红外分光光度仪分析证明得到了预期的产物结构,并测定了产物的特性黏度和固含量。通过静态法对三元共聚物的阻垢性能进行评价,在加剂量为50mg/L时阻碳酸钙率最佳可达93.6%,是一种性能优异的阻垢剂。     

聚丙烯腈/聚氨酯接枝共聚物的合成与表征

合成了带不饱和端基的聚氨酯预聚体(USPU)，并进一步与丙烯腈(AN)单体进行共聚，制备了主链是聚丙烯腈，支链是聚氨酯的接枝共聚物。结果表明，随着引发剂用量的增加，共聚产物收率也随之增大；USPU种类及单体投料比对共聚物收率也有较明显的影响；随着相对分子质量调节剂异丙醇用量的增加，共聚物的特性黏度有下降的趋势。应用FTIR、^1H核磁共振、X衍射对USPU和AN／USPU接枝共聚物进行结构表征，证实了所合成的产物符合预期的结构。     

衣康酸含量对聚丙烯腈环化反应动力学的影响

采用溶液共聚合法合成丙烯腈(AN)与衣康酸(IA)的共聚物。借助傅里叶变换红外光谱和差示扫描量热分析研究了共聚单体IA含量对聚丙烯腈(PAN)结构及环化反应动力学的影响。结果表明,IA的加入促进环化反应在低温下引发,并有效缓解集中放热。随着IA含量的增加,放热反应速率降低,放热峰变宽。采用Kissinger方法计算了不同IA含量的环化反应动力学参数,结果表明,IA可以显著降低环化反应的活化能。但是随IA含量的增加,自由基机理引发的反应活化能增加。     

Monte Carlo simulation of sequential structure control of AN-MA-IA aqueous copolymerization by different operation modes

The regulation of polyacrylonitrile (PAN) copolymer composition and sequence structure is the precondition for producing high-quality carbon fiber high quality. In this work, the sequential structure control of acrylonitrile (AN), methyl acrylate (MA) and itaconic acid (IA) aqueous copolymerization was investigated by Monte Carlo (MC) simulation. The parameters used in Monte Carlo were optimized via machine learning (ML) and genetic algorithms (GA) using the experimental data from batch copolymerization. The results reveal that it is difficult to control the aqueous copolymerization to obtain PAN copolymer with uniform sequence structure by batch polymerization with one-time feeding. By contrary, it is found that the PAN copolymer with uniform composition and sequence structure can be obtained by adjusting IA feeding quantity in each reactor of a train of five CSTRs. Hopefully, the results obtained in this work can provide valuable information for the understanding and optimization of AN copolymerization process to obtain high-quality PAN copolymer precursor.     

Monte Carlo simulation of sequence distributions of acrylonitrile copolymers

A Monte Carlo simulation examining the effect of monomer ratios on the composition and sequence distribution of acrylonitrile(AN) copolymers with N‐vinyl pyrrolidone (NVP), itaconic acid (IA), and acrylic acid (AA) as comonomers has been developed. The Kelen–Tudos method was used to estimate monomer reactivity ratios. The results of the simulation are consistent with the academic conclusion and are as foreseen by the experimental data. The average number of NVP identical monomers in a sequence length of AN/NVP copolymer chain increases continuously and the average number of AN identical monomers in a sequence length shows a prominent decrease with an increase of NVP concentration in the feed. Changes in the monomer average number of AN/IA and AN/AA copolymers in a sequence length were the same as those of AN/NVP copolymer with an increase of comonomer concentration in the feed. The optimum weight ratio of AN with comonomers for manufacturing carbon fibers is 98/2. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 483–488, 2005     

High char‐yielding poly[acrylonitrile‐co‐(itaconic acid)‐co‐(methyl acrylate)]: synthesis and properties

Polyacrylonitrile terpolymers of various compositions consisting of acrylonitrile (AN), itaconic acid (IA) and methyl acrylate (MA) were synthesized by solution polymerization in dimethylsulfoxide. Increase in concentration of either IA or MA retarded the overall polymerization rate and the polymer molecular weight. The system consisting of AN + MA and varying IA concentration was more prone to retardation in comparison with the system composed of AN + IA with variable MA concentration. The retardation factors were quantified. Minor quantities of MA boost the reactivity of IA in the terpolymer system. The terpolymer was richer in MA vis‐à‐vis the feed. The thermal characteristics of the terpolymer were examined as a function of its composition. In contrast to the copolymer of AN and IA requiring 1–1.5 mol% IA, the terpolymer required an IA content of approximately 2.5 mol% for optimum thermal stability. The polymer with 90 mol% AN, 2.5 mol% IA and 7.5 mol% MA exhibited reasonably good char‐forming characteristics and thermal stability. The overall crystallinity and crystallite size of the polymers were found to decrease on incorporation of the comonomers. The ‘aromatization index’ of the copolymer increased with the temperature of pyrolysis through re‐organization of the tetrahydropyridine ladder structure. Copyright © 2005 Society of Chemical Industry     

AN-VAc-AMPS三元共聚合研究

介绍了丙烯腈 ( A N) -醋酸乙烯 ( VAc) (或丙烯酸甲酯 ( MA ) -2 -丙烯酰胺基 -2 -甲基丙磺酸 (英文缩写 AMPS)三元共聚合体系各组分竞聚率的测定方法 ,并比较三元共聚体系和二元共聚体系的AN /VAc竞聚率 ,对三元连续共聚进行了试验 ,讨论 A MPS含量与染色性的关系 ,聚合工艺条件与转化率关系。对聚合物溶液的流变性能及纺丝工艺 ,纤维的性能作了简单介绍。聚合及纺丝试验结果证明 ,以 AMPS为第三单体的三元共聚体系可纺性良好 ,所得纤维的物理性能、染色性能、吸水性和抗静电性均优于一般腈纶     

Porous acrylonitrile/itaconic acid copolymers prepared by suspended emulsion polymerization

Porous acrylonitrile (AN)/itaconic acid (IA) copolymers were successfully prepared by suspended emulsion polymerization for the first time, with potassium peroxydisulfate (KPS) as an initiator, poly(vinyl alcohol) (PVA) as a dispersant agent, and Span80 as an emulsifier. The effects of the water/monomer mass ratio, agitation conditions, KPS concentration, PVA concentration, Span80 concentration,s and IA concentration on the average particle size and size distribution, particle morphology, and porosity of the AN/IA copolymers were investigated. The results show that the final AN/IA copolymers formed with agglomerates of primary particles had a porous structure, low particle density, and uniform particle size and did not agglomerate easily between the particles. The preparation conditions for the AN/IA copolymers were optimized as follows: (1) the water/monomer mass ratio was 0.3 : 1; (2) the concentrations of KPS, IA, PVA, and Span80 were 0.5, 12.4, 0.1, and 0.5 wt %, respectively, based on the weight of AN separately; (3) the agitation rate was 400 rpm; (4) the polymerization temperature was 70°C; and (5) the reaction time was 3 h. The size of the final AN/IA copolymer particles was in the range 200–400 μm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Structural, Physicomechanical, and Sorption Properties of Ternary Acrylonitrile Copolymer Fibres

When itaconic acid (IA) is replaced by vinylcaprolactam (VCL) in ternary AN:MA:IA (acrylonitrile:methyl acrylate:itaconic acid) copolymers, fibres similar in structure to industrial Nitron fibre are obtained, and they have a higher capacity for orientation the larger the amount of VCL added to the copolymer. The fibres obtained have higher physicomechanical properties and higher hydrophilicity and dyeability with disperse dyes than Nitron fibres. The values of the diffusion coefficient of equilibrium-sorbed dye, activation energy, and some thermodynamic properties are calculated. An increase in the VCL content in the copolymer and an increase in the temperature cause an increase in the degree of fixation of the disperse dye in the fibre. In ordinary dyeing conditions, a high residual dye content in the fibre can be attained.     

Influence of block lengths and symmetries of block copolymers on phase behavior of polymer A/polymer B/block copolymer ternary blends

Monte Carlo simulations were used to investigate the compatibilizing effects of diblock copolymers in A/B/A-B diblock copolymer ternary blends and triblock copolymers in A/B/triblock copolymer ternary blends, respectively. The volume fraction of homopolymer A was 19% and was the dispersed phase. The simulation results show that diblock copolymers with longer A-blocks are more efficient as compatibilizers, and symmetric triblock copolymers with a shorter middle block length are easily able to bridge each other through the association of the end blocks. This kind of triblock copolymers have relatively high ability to retard phase separation as compatibilizers.     

偏氯乙烯/丙烯腈/苯乙烯悬浮共聚合动力学

本文研究了偏氯乙烯（ＶＤＣ）／丙烯腈（ＡＮ）／苯乙烯（Ｓｔ）三元悬浮共聚合体系的聚合机理、共聚速率、非聚物组成及其特性粘度的影响因素。实验表明随着投料配比的改变,可分成四个不同聚合机理区域。Ｓｔ对ＶＤＣ／ＡＮ／Ｓｔ三元悬浮共聚有缓聚作用。ＶＤＣ三元悬浮共聚速率可用半经验模型,ｄＣ／ｄｔ＝αＣ＾β「Ⅰ」ｏ＾γｅｘｐ（－γｋｄｔ）描述,由实验得到模型参数γ值为２．２４,模型参数α、β是聚合温度与引发剂浓度的函数。ＶＤＣ－ＡＮ－Ｓｔ三元悬浮共聚物存在着较宽的ＶＤＣ组成分布,并受到单体ＡＮ水溶性的影响,经ＡＮ动态相平衡校正后,可预测ＶＤＣ三元共聚物组成。ＶＤＣ－ＡＮ－Ｓｔ共聚物的特性粘度随着转化率的升高而增大。在相同引发剂用量下,高转化率ＶＤＣ－ＡＮ－Ｓｔ共聚物特性粘度的对数与温度的倒数成线性关系。