丙烯腈/丙烯酸甲酯/衣康酸三元共聚物序列结构的Monte Carlo模拟

以丙烯腈(AN)、丙烯酸甲酯(MA)、衣康酸(IA)为共聚单体,合成碳纤维用聚丙烯腈原丝的三元共聚物,利用Monte Carlo法模拟了AN／MA／IA三元共聚物的组成和序列结构,讨论了共聚单体对共聚物分子链序列结构的影响,探讨了增加序列结构均匀性的方案。结果表明:Monte Carlo法可以较为准确的模拟该共聚物的序列结构;AN／MA／IA以98／0.7／1.3的单体配比可以得到序列结构比较理想的共聚物;采取分批加入IA的方法,使共聚物的序列结构均匀性得到提高。     

少量共单体对丙烯腈在DMF中溶液聚合的影响

研究了丙烯腈与少量衣康酸、丙烯酸、丙烯酸甲酯、甲基丙烯酸甲酯、丙烯酰胺等共单体在N,N-二甲基甲酰胺(DMF)中溶液共聚时的云点阈值。提出共单体云点迹线斜率的概念,用以比较不同共单体对丙烯腈聚合物的改性作用,发现相比其他几种烯类单体衣康酸更适合于用作碳纤维原丝的共单体。同时考察了衣康酸与丙烯腈在DMF中溶液共聚时,其含量对聚合动力学的影响。发现随衣康酸用量的增加,聚合速率与分子量都降低。分析了间歇共聚中共单体含量随转化率的变化,并拟合了该单体对溶液共聚时的竞聚率,发现接近于理想共聚:rIA=2.0、rAN=0.5;且在低共单含量时,共聚物的累积平均共单组成随转化率线性地下降。     

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。     

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。     

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。     

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。     

丙烯腈/β-衣康酸单甲酯共聚物制备及性能的研究

以丙烯腈和β-衣康酸单甲酯为共聚单体,偶氮二异丁腈为引发剂,使用自由基溶液聚合的方法在二甲基亚砜体系中制备丙烯腈共聚物。测试聚合体系的转化率、牛顿黏度和黏均分子质量,采用DSC分析了丙烯腈/β-衣康酸单甲酯共聚物的热性能,并测试了其原丝的力学性能。研究结果表明:丙烯腈/β-衣康酸单甲酯共聚物的黏均分子质量达到了1.28×105,β-衣康酸单甲酯有效降低了共聚物的放热起始温度,纺制出的原丝强度高达8.8 cN/dtex,性能稳定。     

IA/AA/AMPS三元共聚物的合成及阻垢性能研究

以水作溶剂,过硫酸铵为引发剂,衣康酸(IA)、丙烯酸(AA)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)为单体,合成了IA/AA /AMPS三元共聚物.探讨了引发剂用量、链转移剂用量、反应温度等对共聚物阻垢性能的影响.结果表明,引发剂用量为单体总质量的4.5%,链转移剂用量为单体总质量的9.5%,反应温度为95℃时,共聚...     

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。     

过硫酸铵引发丙烯腈/衣康酸铵共聚合研究

为了合成高分子量的聚丙烯腈(PAN),选择衣康酸铵[(NH4)2IA]作为共聚单体,以过硫酸铵[(NH4)2S2O8]作为引发剂,采用水相沉淀聚合工艺,研究了单体配比对聚合反应的影响。利用元素分析、热分析和红外光谱研究了不同单体配比条件下共聚物的氧摩尔分数、热性能和结构特征。结果表明,水相沉淀聚合反应速率较快,且制得了粘均分子量高达58.46×104,(NH4)2IA的摩尔分数高达11.925%的聚丙烯腈共聚物;单体配比对共聚物的热性能有较大影响;红外光谱中有N—H键和羰基C＝O的伸缩振动,表明聚合物链中有(NH4)2IA存在。     

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     

Texture and Properties of Acrylonitrile–Ammonium Itaconate Copolymer Precursor Fibers and Carbon Fibers

Acrylonitrile–ammonium itaconate copolymer {P[AN-co-(NH₄)₂IA]} was fabricated by free-radical solution copolymerization of acrylonitrile (AN) and ammonium itaconate [(NH₄)₂IA]. The copolymer was confected into a spinning solution (dope) and spun into precursor fibers. Then the precursor fibers were converted to carbon fibers by stabilization and carbonization processes. Another copolymer of acrylonitrile–itaconic acid [P(AN-co-IA)] and its resultant fibers were studied in contrast. Due to preferable hydrophilicity and facilitating cyclization reaction in stabilization process, P[AN-co-(NH₄)₂IA] fibers could increase the draw-ratio in the spinning process and in the stabilization process to attenuate some property-limiting facts in precursor fibers and carbon fibers. It has been found P[AN-co-(NH₄)₂IA] precursor fibers gave a 30% improvement in tenacity over P(AN-co-IA) precursor fibers. Results for P[AN-co-(NH₄)₂IA] precursor fibers carbonized at 1400°C ultimately showed a 26.7% increase in carbon fiber tensile strength over P(AN-co-IA) based carbon fibers. Characterization analysis using scanning electron microscope (SEM), transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) manifested that these improvements are due to fewer surface defects, better interior morphology, higher degree of orientation and graphitization.     

聚合条件对P（AN-co—IA）分子质量分布影响的研究

采用凝胶色谱（GPC）法测定了丙烯腈与衣康酸共聚物P（AN—co—IA）的重均分子质量和数均分子质量,并通过已知聚丙烯腈的重均分子质量数据和数均分子质量数据对所测的分子质量进行校正,进一步计算得到共聚物的多分散系数。同时研究了引发剂用量、单体浓度、聚合温度、聚合时间对P（AN—co—IA）分子质量分布的影响。研究结果表明,P（AN-co-IA）分子质量分布随引发剂用量的增大、聚合单体浓度的增加而变宽,与聚合反应温度、聚合反应时间无明显的变化趋势。     

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     

Kinetic study of radical polymerization. VII. Investigation into the solution copolymerization of acrylonitrile and itaconic acid by real‐time 1H NMR spectroscopy

Free radical solution copolymerization of acrylonitrile (AN) and itaconic acid (IA) was performed with DMSO‐d₆ as the solvent and 2,2′‐azobisisobutyronitrile (AIBN) as the initiator. Weight ratio of the monomers to solvent and molar ratio of initiator to monomers were constant in all experiments. The initial comonomer composition was the only variable in this study. On‐line ¹H NMR spectroscopy was applied to follow individual monomer conversion. Mole fraction of AN and IA in the reaction mixture (f) and in the copolymer chain (F) were measured with progress of the copolymerization reaction. Overall monomer conversion versus time and also compositions of monomer mixture and copolymer as a function of overall monomer conversion were calculated from the data of individual monomer conversion versus time. Total rate constant for the copolymerization reaction was calculated by using the overall monomer conversion versus time data and then k_p/k_t^0.5 was estimated. The dependency of k_p/k_t^0.5 on IA concentration was studied and it was found that this ratio decreases by increasing the mole fraction of IA in the initial feed. The variation of comonomer and copolymer compositions as a function of overall monomer conversion was calculated theoretically by the terminal model equations and compared with the experimental data. Instantaneous copolymer composition curve showed the formation of alternating copolymer chain during copolymerization reaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3253–3260, 2007     

Study on monomer reactivity ratios of acrylonitrile/itaconic acid in aqueous deposited copolymerization system initiated by ammonium persulfate

A single water-soluble initiator-ammonium persulfate (APS), not containing alkali metal ions, was first utilized to initiate copolymerization of acrylonitrile (AN)/itaconic acid (IA) in aqueous deposited copolymerization system. Monomer reactivity ratios of this polymerization system were investigated using element analysis method and Q–e schemes. It was found that the monomer reactivity ratios of AN/IA calculated from Q–e schemes are 0.505 (r _AN) and 1.928 (r _IA), while the monomer reactivity ratios of AN/IA in aqueous deposited copolymerization system at 60 °C are 0.64 (r _AN) and 1.37 (r _IA) calculated from Kelen–Tüdõs method, 0.61 (r _AN) and 1.47 (r _IA) from Fineman–Ross method. The three pairs of monomer reactivity ratios are in good agreement. With the increase of the polymerization temperature, the monomer reactivity ratios of AN and IA approach to unity, indicating that the aqueous deposited copolymerization of AN/IA has a tendency to ideal copolymerization. At lower polymerization conversion, the monomer reactivity ratios of AN and IA have hardly any changes. When the polymerization conversion is more than 5%, the monomer reactivity ratio of AN increases, while that of IA decreases.     

丙烯腈与丙烯酸的共聚合及表征

以偶氮二异丁腈为引发剂 ,研究了丙烯腈与丙烯酸在二甲基亚砜中的自由基溶液共聚合反应。考察了单体浓度 ,引发剂浓度 ,反应温度和时间等对共聚反应的影响。分别用称重法和乌氏粘度计测定了反应的转化率和产物的相对分子质量。用 IR,DSC和 TG对产物的结构和性能进行了表征。研究结果表明 ,最佳的反应条件是 :总单体浓度 2 2 % ,AIBN占总单体浓度 1 % ,反应温度和时间为 6 0℃和 2 4h     

Copolymerization of acrylonitrile,methyl acrylate,and itaconic acid in thiocyanate solutions in the presence of hydrolyzed nitron fibre waste

Conclusions -- The kinetics of the copolymerization process of AN, MA, and IA in the presence of hydrolyzed Nitron fibre characterized by various degrees of hydrolysis has been studied. It has been found that introducing H-PAN into the reaction mixture leads to an increase in degree of conversion in the copolymerization process and to an increase in molecular weight of the copolymer synthesized.-- Fibre has been spun from the products of joint copolymerization of AN, MA, and IA in the presence of H-PAN with various concentrations of these in the solution and various SEC values. Introducing up to 5% by wt. of an H-PAN with an SEC not over 0.2 meq/g into the reaction mixture aids in obtaining fibres with satisfactory properties and opens up the possibility of still another way of solving the question of regenerating wet Nitron fibre wastes.Translated from Khimicheskie Volokna, No. 4, pp. 17–19, July–August, 1991.