丙烯腈与衣康酸在DMSO/H_2O中的聚合及聚合物性能表征

采用丙烯腈 (AN)与衣康酸 (IA)为共聚单体 ,以偶氮二异丁腈为引发剂在混合介质二甲基亚砜 水(DMSO H2 O)中自由基沉淀共聚合 ,合成了高分子量的聚丙烯腈 .通过正交设计方法研究了聚合反应条件 ,如反应温度、单体浓度、混合介质DMSO H2 O配比等对聚合反应的转化率的影响 ,还重点探讨了混合介质DMSO H2 O配比对转化率和粘均分子量的影响 .采用DSC ,TG ,IR等手段研究了PAN均聚物及 (PAN co IA)的结构与性能 .研究结果表明 ,增加反应温度 ,降低单体浓度 ,降低喂料AN IA配比中IA的含量 ,均有利于提高聚合反应的转化率 .AN与IA共聚反应的转化率随着反应介质中DMSO含量的增加而降低 ,同时聚合物的粘均分子量也降低 .对于喂料AN IA配比中IA含量相同的P(AN co IA)共聚物 ,高分子量P(AN co IA)共聚物比常规低分子量的放热峰起始温度低 ,放热峰宽     

云点法研究丙烯腈共聚体系反应活性及其与热稳定性能的关联

采用滴定实验法分别测试了衣康酸(IA)、丙烯酰胺(AM)、丙烯酸甲酯(MA)与丙烯腈(AN)一系列单体组成比时的云点;采用红外光谱、示差扫描量热分析和热失重分析研究了共聚单体的选择对共聚物热稳定化反应的影响和机理及其与共聚体系反应活性的关联.结果显示,IA、AM或MA的引入有利于提高AN聚合体系的云点,不同共单体用量构成的云点迹线斜率可以比较共聚体系反应活性,并对AN共聚体系组成的优化选择具有普适性;而AN与IA较高的共聚反应活性使得P(AN/IA)聚合物热稳定性能好,氰基未环化指数、环化反应起始温度及表观活化能低,环化反应速率快,这可能由于IA分子结构含有2个羧基,引发活性点较多,可以在低温条件下引发氰基环化形成更多的梯形结构.     

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。     

1-烯丙基-3-甲基咪唑离子液体单体与丙烯腈共聚行为的研究

以1-烯丙基-3-甲基咪唑盐酸盐([AMIM]Cl)作为离子液体单体,偶氮二异丁腈作为引发剂,二甲基亚砜为溶剂,实现了与丙烯腈(AN)在不同反应条件下的自由基共聚合.研究了AN/[AMIM]Cl二元共聚合的动力学,得到了相应的竞聚率数据(rAN=8.11,r[AMIM]Cl=0).用1H-NMR、GPC、DSC、TGA等手段对共聚物进行了表征.通过对AN/[AMIM]Cl二元共聚及AN/IA/[AMIM]Cl三元共聚的研究发现,[AMIM]Cl在与丙烯腈共聚时具有双重作用,一部分离子单体进入到共聚物的分子链中调节其亲水性及可纺性,剩下的大部分留在纺丝液中可显著降低纺丝液的黏度,从而使高分子量高固含量纺丝液的纺制成为可能,有望得到高性能的碳纤维原丝.     

β-蒎烯和马来酸酐的反应及产物表征

研究了β-蒎烯和马来酸酐的烯反应、溶剂中自由基共聚反应和本体热共聚反应,得到了β-蒎烯和马来酸酐烯反应产物和共聚产物,并用IR、1H NMR、13C NMR、GPC、DSC进行表征,研究了引发剂浓度、溶剂体系、单体配比、温度等因素对产物的影响.对聚合物进行皂化改性,测量了皂化物浓度对水表面张力的影响.     

PEB/MMA-AN悬浮接枝共聚反应机理

研究了乙烯-1-丁烯共聚物(PEB)弹性体与甲基丙烯酸甲酯(MMA)-丙烯腈(AN)悬浮接枝共聚反应行为及接枝共聚产物对SAN树脂增韧作用随反应时间的变化规律, 用凝胶渗透色谱法和傅里叶变换红外光谱法对接枝共聚产物进行了表征, 分析了接枝共聚反应机理, 推算了接枝链分子量. 结果表明, 体系首先发生链增长自由基向PEB转移终止形成非接枝共聚物(MAN_L)和PEB大分子自由基引发单体共聚形成接枝链(g-MAN)的反应, 接枝反应结束后体系发生明显的非接枝共聚形成非接枝共聚物(MAN_H)的反应; MAN_L的分子量低于g-MAN的分子量, 而g-MAN的分子量明显低于MAN_H的分子量; 在接枝共聚过程中发生已接枝和未接枝PEB断链并随机再接生成多嵌段共聚物的副反应; 在反应初期, 接枝链的AN单元含量接近于非接枝共聚物的AN单元含量, 在反应中后期前者远低于后者.     

IA/ASP/AMPS三元共聚物合成及阻垢性能

以衣康酸(IA)、天冬氨酸(ASP)和2-丙烯酰胺-2-甲基丙磺酸(AMPS)为单体,在过硫酸铵引发下采用水溶液自由基聚合方法制备了新型IA/ASP/AMPS三元共聚物阻垢剂,并利用红外光谱仪对其结构进行分析表征。通过正交实验和单因素实验考察单体摩尔配比、引发剂用量、反应温度及反应时间对共聚产物阻垢性能的影响,确定其最佳合成条件。实验结果表明:共聚单体的摩尔比nIA:nASP:nAMPS为3:1:0. 5,引发剂用量占单体总质量的10%,反应温度为85℃,反应时间为4 h时,合成三元共聚物对碳酸钙、硫酸钙及磷酸钙的阻垢性能最好,阻垢率分别达91%、95%及96%以上;此共聚物的固含量和黏均相对分子质量分别为30. 5%、1402。静态阻垢法评价温度对IA/ASP/AMPS共聚物阻垢性能的影响,结果表明,IA/ASP/AMPS共聚物适用于含碳酸钙、磷酸钙的高温循环冷却水体系。     

四氯化钛/三异丁基铝体系催化降冰片烯与异戊二烯的共聚合

以传统Ziegler-Natta催化体系TiCl4/Al(#em/em#-Bu)3催化降冰片烯(NBE)和异戊二烯(IP)的共聚合, 制得可溶于常规有机溶剂的共聚物, 其数均分子量为2.0 × 104~6.5 × 104, 分子量分布指数为1.5~2.9, 降冰片烯结构摩尔含量为26%~60%. 考察了助催化剂用量、 聚合温度及2种单体投料比对共聚合的影响. 结果表明, 当降冰片烯与异戊二烯的投料摩尔比为4∶6时, 于40 ℃聚合6 h, 得到的共聚物产率为96%, 数均分子量为6.5×104, 降冰片烯结构含量45%. 用 1H NMR, 13CNMR, GPC和DSC等方法表征了共聚产物的微观结构与热性能. 13C NMR DEPT结果表明, 共聚反应中降冰片烯单体以加成方式聚合. DSC结果显示, 共聚物只有一个玻璃化转变温度(Tg=20~40 ℃). 通过Kelen-Tüdös方法得到2种单体的竞聚率分别为rNBE=0.07, rIP=0.44.     

乙烯-甲基丙烯酸甲酯共聚物结构的~1H NMR和~(13)C NMR表征

采用核磁共振(1H NMR、13C NMR)技术对由双[N-(2,6-二异丙基苯基)-3-异丙基水杨醛亚胺]镍(Ⅱ)配合物/甲基铝氧烷(Methylaluminoxane,MAO)催化乙烯-甲基丙烯酸甲酯共聚得到的共聚物(EMMA-a)的微观结构和组成进行了详细的分析与表征,同时对自由基聚合制得的乙烯-甲基丙烯酸甲酯共聚物(EMMA-b)作了相应的分析与表征。通过1H NMR数据,计算得到两种共聚物样品中共聚单体甲基丙烯酸甲酯(MMA)的插入率分别为14.10%和10.26%(摩尔百分数)。基于13C NMR数据,分析比较了由配位共聚与自由基共聚所得共聚物样品在微观结构上的区别,结果发现,在共聚物的乙烯链段部分,由配位共聚得到的共聚物样品EMMA-a主要含有甲基型支链,而由自由基共聚所得共聚物样品EMMA-b具有长链型支链。另外,在共聚物的MMA链节部分,EMMA-a中的MMA单元的羰基(C‖O)碳的化学位移为177.27,而EMMA-b中的MMA单元的羰基(C‖O)碳的化学位移为175.96。     

四氟乙烯/偏氟乙烯乳液共聚反应的竞聚率测定

用亨利定律关联了四氟乙烯 (TFE) /偏氟乙烯 (VDF)乳液共聚合体系中的单体气相分压与其对应液相浓度间的关系 ,推导了用气相摩尔分数表示的共聚物组成方程式 .通过气相色谱和19F NMR分别测定了共聚反应前后气相单体组成和共聚物组成 ,用非线性回归法 (RREVM )计算TFE/VDF乳液共聚合反应表观竞聚率分别为γTFE=0 35和γVDF=0 6 3 .将实测的表观竞聚率代入共聚物组成方程计算共聚物组成与由19F NMR测定的结果一致 ,为进一步的工业放大试验提供科学依据     

NiSO_4改性对聚丙烯腈原丝及其碳纤维结构与性能的影响

碳纤维具有高比强度、高比模量、导电、耐热、自润滑等优异的综合性能,在纤维增强复合材料中得到了广泛的应用.可制备碳纤维的前驱体有人造丝、沥青、聚丙烯腈纤维、木质素、聚乙烯纤维、聚苯并噻唑(PBO)纤维等.但大多数高强碳纤维目前仍然是由聚丙烯腈纤维制备的,同时,许多工作都集中在更进一步提高碳纤维的机械性能.特别是在我国, 碳纤维质量与某些发达国家相比,还有较大的差距,急需解决的问题就是如何尽快研制出高力学性能的碳纤维.采用氨基硅氧烷、脂肪族羧酸[1]、CuCl[2]、KMnO 4[3]、CoCl2[4]等有机或无机化学试剂对聚丙烯腈原丝进行化学处理, 以改进最终碳纤维的结构与性能是一种有效的方法.国内在这方面的研究还很少.文献[1 ～4]中所采用的方法都是利用商业聚丙烯腈原丝在碳化前进行洗油、浸渍、洗涤烘干处理 ,增加了碳纤维制备的工序,同时,原丝损伤较大,在连续生产中难以适用.我们在原丝连续制备的同时采用NiSO4溶液浸渍处理聚丙烯腈纤维,本文主要研究了采用NiSO4浸渍改性后聚丙烯腈原丝及其碳纤维的结构与性能.研究表明,采用NiSO4在线浸渍改性聚丙烯腈原丝,生产工艺简单,且能有效地改进最终碳纤维的结构与性能.     

Property changes of powdery polyacrylonitrile synthesized by aqueous suspension polymerization during heat-treatment process under air atmosphere

High molecular weight powdery polyacrylonitrile (PAN) polymers were prepared by aqueous suspension polymerization employing itaconic acid (IA) as comonomer and alpha,alpha(')-azobisisobutyronitrile (AIBN) as initiator at 60 degrees C. PAN polymers obtained with different monomer ratios were characterized by EA, DSC, FTIR and XRD. It is investigated that the oxygen element content in PAN polymers increased with the increase of required IA amounts in the feed and heat-treatment temperatures. DSC curves of PAN copolymers exhibited the triplet character, owing to the exothermic cyclization and oxidative reactions during heat-treatment process. Introduction of IA in the feed relaxed exothermic reactions of PAN polymers under air atmosphere. Structure and crystallinity changes were affected by required IA amounts in the feed and enhancement of heat-treatment temperatures. The characteristic functional groups (including C[triple bond]N, C=O, CH(2)) presented in FTIR spectra of PAN polymers indicated copolymerization reaction of AN and IA. Existence of some organic groups (C-O, C=C and/or C=N) indicated formation of ladderlike structure during heat-treatment process. PAN homopolymer had the better crystallinity (mainly peak intensity and peak area around 2theta = 17 degrees) than most RT-PAN copolymers. When heat-treatment temperature is around 210 degrees C, peak intensity, peak area, L(c) and CI of HT-PAN polymers corresponding to samples 1# and 2# got maxima, while crystallinity became weak at higher heat-treatment temperatures.     

Structure evolution mechanism of poly(acrylonitrile/itaconic acid/acrylamide) during thermal oxidative stabilization process

Polyacrylonitrile (PAN) polymers with different compositions were prepared by an efficient aqueous free-radical polymerization technique.Thermal properties of polyacrylonitrile homopolymer (PAN),poly(acrylonitrile/itaconic acid) [P(AN/IA)] and poly(acrylonitrile/itaconic acid/acrylamide) [P(AN/IA/AM)] were studied by Fourier transform infrared spectroscopy,X-ray diffraction,differential scanning calorimetry and thermogravimetry in detail.It was found that AM had the ability to initiate and accelerate thermal oxidative stabilization process,which was confirmed by the lower initiation temperature and broader exothermic peak in P(AN/IA/AM) as compared with that in P(AN/IA) and PAN.The intensity of heat releasing during the thermal treatment was relaxed due to the presence of two separated exothermic peaks.Accompanied by DSC analysis and calculation of the apparent activation energy of cyclization reaction,two peaks were assigned to the ionic and free radical induction mechanisms,respectively.The higher rate constant in P(AN/IA/AM) indicated that the ionic mechanism actually had a kinetic advantage at promoting thermal stability over the free radical mechanism.This study clearly show that the synthesized P(AN/IA/AM) terpolymers possess larger room to adjust manufacture parameters to fabricate high performance of PAN-based carbon fibers.     

较高等规度丙烯腈成纤聚合物的合成

以无水氯化镁为添加剂,考察了不同条件下的丙烯腈聚合反应,研究了溶剂种类、聚合温度和氯化镁与丙烯腈的摩尔配比对聚合反应及聚合物等规度的影响,并确定了最佳反应条件,正己烷为溶剂,偶氮二异丁腈(AIBN)为引发剂,聚合温度为60℃,氯化镁与丙烯腈的摩尔比为2∶1.在此条件下,研究了单体浓度和引发剂浓度对丙烯腈(AN)均聚合、丙烯腈/衣康酸(AN/IA)二元共聚合和丙烯腈/衣康酸/丙烯酸甲酯(AN/IA/MA)三元共聚合反应的影响,并获得了较高等规度(三单元组全同分数30.2%～55.9%)的丙烯腈均聚物和共聚物.不同等规度的丙烯腈聚合物的热分析(DSC及TGA)表明,随着聚合物等规度的提高,聚合物的环化放热峰值温度向高温区移动,而且随着聚合物等规度的提高,环化放热峰变宽.随着聚合物等规度的提高,聚合物的热稳定性变差,热失重增加,碳收率降低.     

Copolymerization of acrylonitrile with itaconic acid in dimethylformamide: effect of triethylamine

The copolymerization of acrylonitrile (AN) in dimethylformamide (DMF) was retarded by the presence of itaconic acid (IA) comonomer. Addition of TEA helped overcome the retardation at enhanced concentrations of IA in the feed. The monomer reactivity ratios determined by both terminal and penultimate models revealed that the overall monomer reactivity’s are practically unaffected by the presence of TEA. The penultimate-unit effect for radicals terminated in AN was enhanced by the presence of TEA. Higher TEA concentrations helped regain the reactivities of AN and IA to AN-radical to the state in pure DMF. The penultimate model could explain the feed-copolymer composition profile for the whole range. Whereas IA systematically retarded the polymerization rate at all concentration regime in DMF, it increased the rate at higher IA concentration in DMF/TEA system. For a given IA concentration, the polymerization rate decreased as the solvent is enriched in TEA. The copolymers synthesized in the presence of TEA, manifested higher cyclization temperature and consequently lower char residue, attributed to the incorporation of TEA in the polymer by means of salt formation with IA moiety camouflaging the catalytic effect of the -COOH group in cyclization reaction. ¹³C-NMR studies confirmed the incorporation of the TEA molecules in the polymer chain.     

辐射引发丙烯腈－丙烯酸甲酯－衣康酸三元沉淀共聚合

辐射引发丙烯腈－丙烯酸甲酯－衣康酸三元沉淀共聚合张志成,葛学武,葛敏,张健（中国科学技术大学应用化学系,合肥,２３００２６）关键词聚丙烯腈,超高分子量,辐射引发,沉淀共聚合制备高性能的碳纤维,首先要制备优良的丙烯腈基原丝（ＳＡＦ）．ＳＡＦ聚合物具有超...     

Thermal behavior of polyacrylonitrile polymers synthesized under different conditions and comonomer compositions

Polyacrylonitrile (PAN) polymers are used as precursors for carbon fiber production. This process requires an oxidative stabilization step, which can be studied by differential scanning calorimetry (DSC). In this sense, thermal behavior of PAN based terpolymers by different polymerization processes, compositions and itaconic acid concentrations in the reaction media were investigated. The obtained results showed that the addition of itaconic acid and methyl acrylate as comonomers resulted a lower heat flow during the process comparing to the PAN homopolymer. It suggested that these comonomers aid the oxidative stabilization stage for all studied process. The redox system polymerization at 40°C resulted in a lower heat flow. Itaconic acid decreases slightly initial and peak temperatures of the terpolymer and heat flow until concentration of 3y. The cyclization temperature decreases when MAis incorporated into the terpolymer compared to the MMA terpolymer and increases when MAA is the acidic monomer. Among terpolymers the AN/MA/AA polymer showed the best thermal behavior for carbon fiber producing.     

乙烯-乙烯醇共聚物的固体核磁共振研究

乙烯 (Ｅ) /乙烯醇 (Ｖ)共聚物 (ＥＶＯＨ)为结晶性高聚物 ,作为膜材料有着广泛的用途 .在该体系中 ,不仅存在复杂的化学和物理结构 ,如序列分布、立构规整性和共晶结构 ,还存在复杂的氢键相互作用 ,是研究化学结构、聚集态结构和氢键相互作用之间关系的代表性体系 .通过ＤＳＣ[1 ] 、Ｘ 射线衍射[2 ] 、固体高分辨核磁共振碳谱 (1 3Ｃ ＣＰ/ＭＡＳ ＮＭＲ) [3～ 7] 等不同的研究方法 ,前人对ＥＶＯＨ体系及与之直接相关的乙烯醇均聚物(ＰＶＡ)的熔融温度、结晶度以及结晶结构等问题进行了大量研究 .1 984年Ｔｅｒａｏ等[6] 首先报道了在固…