三乙酰丙酮钒催化乙烯/1-己烯和乙烯/1,3-丁二烯共聚合反应性能研究

采用三乙酰丙酮钒-倍半乙基铝[V(acac)_3-Et_3Al_2Cl_3]催化体系,研究了乙烯/1-己烯和乙烯/1,3-丁二烯共聚合行为;同时利用核磁共振仪、差示扫描量热仪、流变仪等对共聚物的结构和性能进行了表征。结果表明,V(acac)_3-Et_3Al_2Cl_3催化乙烯/1-己烯得到的共聚物中1-己烯都是以被乙烯单元所隔离的形式而存在,铝钒物质的量比为50时该催化体系达到最高催化活性。V(acac)_3-Et_3Al_2Cl_3催化乙烯/1,3-丁二烯的共聚合得到的共聚物为嵌段共聚物,二烯烃以反式-1,4方式插入共聚物链中。     

双金属催化5-乙烯基-2-降冰片烯与甲基丙烯酸特丁酯共聚

考察了双金属催化剂Fe(acac)3-Al(i-Bu)3(acac=乙酰丙酮)催化5-乙烯基-2-降冰片烯(ENB)与甲基丙烯酸特丁酯(TBMA)共聚反应条件的影响因素。并用核磁共振波谱、红外光谱方法考察了共聚物的组成,用凝胶渗透色谱分析了聚合物的相对分子质量及其分布。结果表明,当n(三异丁基铝)∶n(乙酰丙酮铁)=23∶1,c(乙酰丙酮铁)=2.26×10-3 mol/L,聚合温度为70℃,聚合时间为6 h,溶剂为甲苯,总单体浓度4 mol/L,n(ENB)∶n(TBMA)=1∶1时,共聚物中ENB与TBMA摩尔分数分别为18.2%和81.8%,共聚物分散指数为Mw/Mn=1.33。     

双β-二酮钛系烯烃聚合催化剂的合成、表征及其催化乙烯聚合

合成了一种新型β-二酮钛配合物[(acac)₂Ti(C₆H₆)₂(3a)、(acac)₂Ti(C₆H₅OCH₃)₂(3b)、(acac)₂Ti(C₆H₅CF₃)₂(3c)],采用¹H NMR、¹³C NMR、元素分析等方法进行表征。用配合物作催化剂,以甲基铝氧烷(MAO)为助催化剂催化乙烯聚合,研究了聚合条件(如Al/Ti摩尔比、聚合温度和催化剂结构)对催化活性的影响。其中3a对乙烯聚合活性达6.26×10⁵ g·mol^-1·h^-1,聚合物最大的重均分子量M_w为13.47 kg·mol^-1,分子量分布PDI为2.0。     

钼系催化体系制备高乙烯基含量丁苯共聚物的研究

以磷酸三丁酯(TBP)为配体改性的五氯化钼(MoCl5)为主催化剂、二丁基镁[Mg(Bu)2]为助催化剂组成二元催化体系,在丁二烯(Bd)物质的量浓度为2.6×103 mol·L-1和Bd/苯乙烯(St)质量比为3的条件下进行丁苯共聚物的配位聚合,研究催化体系和聚合条件对聚合反应的影响,并采用凝胶渗透色谱、傅里叶变换红外光谱、核磁共振氢谱、差示扫描量热法等对共聚物的微观结构进行分析。试验得出的最佳反应条件为:TBP/MoCl5物质的量比2,MoCl5/单体物质的量比1×10-3,Mg(Bu)2/MoCl5物质的量比3,聚合温度70℃,聚合时间12 h。在该条件下,Bd和St聚合活性较高,共聚物的数均相对分子质量为1.24×105,相对分子质量分布较宽,Bd单元中1,2-结构物质的量分数大于0.85,聚合产物为高乙烯基含量无规丁苯共聚物。     

甲基丙烯酸甲酯在Nd[O(i-Pr)]3-Al(i-Bu)3-CCl4中配位活性聚合

以Nd[O(i-Pr)]3-Al(i-Bu)3-CCl4为三元络合体系,在甲苯中催化甲基丙烯酸甲酯(MMA)聚合.发现PMMA相对分子质量与转化率呈线性关系,聚合速率与MMA和Nd[O(i-Pr)]3的浓度分别呈一级关系,聚合表观活化能为74.1 kJ/mol.所得PMMA间规摩尔分数约64%.用该催化体系合成了嵌段共聚物PMMA-b-P(HO),表明异丙氧基钕体系在甲苯中催化MMA聚合反应是配位活性聚合.     

甲基丙烯酸甲酯在Nd[O（i—Pr）]—Al（i—Bu）3—CCl4中配位活性聚合

以Nd[O(i-Pr)]3-A1(i-Bu)3-CCl4为三元络合体系，在甲苯中催化甲基丙烯酸甲酯(MMA)聚合。发现PMMA相对分子质量与转化率呈线性关系，聚合速率与MMA和Nd[O(i-Pr)]3的浓度分别呈一级关系，聚合表观活化能为74．1kJ／mol。所得PMMA间规摩尔分数约64％。用该催化体系合成了嵌段共聚物PMMA-b-P(H0)，表明异丙氧基钕体系在甲苯中催化MMA聚合反应是配位活性聚合。     

Cs-对称胺芴二甲基钛络合物催化的乙烯活性聚合

研究了对丙烯的高速间规活性聚合有效的Cs-对称胺芴二甲基钛络合物-干燥修饰甲基铝氧烷(dMMAO)催化剂体系对乙烯的聚合行为的影响。结果表明:乙烯常压聚合表现出稳定的聚合速率,聚合活性达到282 kg-PE/(mol-Ti·h);利用间歇聚合法进行乙烯聚合的单体转化率均达到99%以上,说明催化体系无失活现象,但得到的聚乙烯在135℃下不溶于GPC溶剂邻二氯苯中;采用先加入定量丙烯单体聚合完全结束后,再加入定量乙烯单体进行聚合的方法合成了sPP-b-PE嵌段共聚物。嵌段共聚合的结果说明乙烯聚合是以活性聚合的方式进行的。利用该催化体系还合成了丙烯-乙烯丙烯双嵌段共聚物(sPP-b-E/P)以及丙烯-乙烯丙烯-丙烯(sPP-b-E/P-b-sPP)三嵌段共聚物。     

膦氮配体半茂钛体系催化乙烯均聚合及乙烯与丙烯共聚合

合成了两种配合物中含有膦、氮的半茂钛催化剂,研究了甲基铝氧烷、四(五氟苯基)硼酸盐为助催化剂,不同n(Al)∶n(Ti)对乙烯均聚合及聚合物相对分子质量及其分布的影响。研究了催化剂用量、原料配比、反应压力、反应时间对乙烯与丙烯共聚合及共聚物组成、相对分子质量及其分布的影响。结果表明:合成的膦氮配体半茂催化剂可有效催化乙烯均聚合,在常压下,聚合活性可达0.62×10~6 g/(mol·h),也可以有效催化乙烯与丙烯共聚合,与高活性茂金属催化剂催化效率相近;用该催化剂制备的高相对分子质量乙丙共聚物的相对分子质量分布窄,符合单活性中心催化剂的特点;共聚物的序列结构研究表明,乙烯与丙烯竞聚率之积接近1,共聚物无规性好。     

用新型稀土催化剂催化苯乙烯与异戊二烯共聚合

研究了以亚磷酸二异辛酯为配体的氯化稀土配合物(简称Nd)与三异丁基铝(简称Al)组成的二元稀土催化体系催化苯乙烯与异戊二烯的共聚行为,考察了Al与Nd的摩尔比、聚合温度、单体配比等对共聚行为及共聚物组成和链结构的影响。结果表明,该催化体系能够实现异戊二烯的均聚,但不能催化苯乙烯均聚,而催化二者共聚的活性取决于单体配比且低于异戊二烯的均聚。所得产物为无规共聚物,其中异戊二烯链节以顺式-1,4-结构为主(95%～96%),含少量3,4-结构,几乎不含反式-1,4-结构;共聚物中的结合苯乙烯量随Al与Nd的摩尔比、聚合温度及单体配比中苯乙烯量的增加而增大。苯乙烯以孤立单元形式嵌入在异戊二烯链节之间,因此所得共聚物为"准"无规共聚物;共聚物的重均分子量最高可达19.3×105,分子量分布随着共聚物中结合苯乙烯量的增加而变宽,甚至出现双峰分布。     

Fe(Ⅲ)、Co(Ⅲ)、Co(Ⅱ)、Ni(Ⅱ)乙酰丙酮螯合物的合成及其性能的研究

齐格勒(Ziegler)型均相加氢催化剂在加氢反应中的应用目前还处于开发阶段,但已引起人们的重视。我们对M(acac)_Et_3Al-Py(M=Fe(III)、Co(III)、Co(II)、Ni(II),n=2～3,Py为吡啶)催化体系在用环戊二烯(CPD)选择性加氢制取环戊烯(CPE)中的应用进行了研究,但所用催化剂的母体M(acac)_     

Synthesis of graft copolymer of styrene and acrylonitrile onto poly (butyl acrylate) by using polymeric peroxide

Summary Two-stage seeded emulsion copolymerization of butyl acrylate with tert-butyl 3-isopropenylcumylperoxide (D120) was performed at 70°C . Copolymer latex with 0.2μm of particle size was obtained. Emulsion graft polymerization of styrene and acrylonitrile onto the copolymer of butyl acrylate was initiated by peroxy bonds in the D120 units of the backbone chains at 120°C . Graft copolymers with higher grafting ratio were derived. It was found that the grafting ratio tends to increase with the increasing D120 in feed of copolymerization with butyl acrylate. The graft copolymers were blended with SAN resin, and a kind of AAS resin was obtained. Both elongation at break and Izod impact strength of the AAS resin reached maximum at grafting ratio of 0.25, which were comparable with the values of ABS resin for general purpose. A method to improve the grafting efficiency on the saturated polyacrylate elastomer rubber was developed. Received: 6 March 2002 / Revised version: 8 May 2002 / Accepted: 13 May 2002     

The effect of the compostion of heterogeneous polymerization catalyst on ethylene–1-butene copolymerization

The effect of ethylaluminium dichloride (EADC) in the heterogeneous Ziegler-Natta catalyst on the ethylene–1-butene copolymerization and the molecular structure of the resulting copolymer was investigated. SiO₂-supported TiCl₄ catalysts having different EADC/Ti molar ratio were prepared by changing the amount of EADC in feed during the catalyst preparation. Ti oxidation states of the prepared catalysts were changed with EADC/Ti molar ratio, and it contained the higher fraction of Ti(3+) and Ti(2+) at the higher EADC/Ti molar ratio. The change in EADC/Ti molar ratio of the catalyst was also shown to influence on the copolymerization performance. Xylene-solublility value corresponding to the fraction having low molecular weight with higher 1-butene content, decreased as EADC/Ti molar ratio decreased. The chemical compositional distribution of PE copolymer was shown not to be affected by EADC/Ti molar ratio of the catalyst significantly.     

Copolymerization of norbornene and methyl acrylate catalyzed by Nd(naph)<Subscript>3</Subscript>–Al(i-Bu)<Subscript>3</Subscript>

The copolymerization of norbornene (NB) and methyl acrylate (MA) catalyzed by Nd(naph)₃–Al(i-Bu)₃ and the structure of the copolymers are studied in this article. All polymerization reactions were carried out under nitrogen atmosphere using syringe technique. The copolymers are characterized by IR, ¹H NMR, ¹³C NMR, GPC, and TGA. Norbornene and methyl acrylate are 22.2 and 77.8 mol%, respectively, in the copolymer. The molecular weight distribution is M_w/M_n < 2.0. The molecular weight of copolymer changes with the change of NB/MA in molar ratio. Molecular weight and its distribution of copolymer decrease as molar ratio of NB/MA increases. The copolymerization can be performed in solvents such as aromatic hydrocarbon. The copolymerization can be obtained at room temperature, whereas the copolymer yield increases with increasing reaction temperature. The yield of copolymer changes with the Al/Nd molar ratio with a preferable Al/Nd molar ratio of 30.     

Semicontinuous emulsion copolymerization of acrylonitrile,butyl acrylate,and styrene

Semicontinuous emulsion copolymerization of acrylonitrile (M₁), butyl acrylate (M₂), and styrene (M₃) was investigated. The copolymerization proceeded under the conditions used with a high degree of conversion, whereby a stationary state characterized by a constant monomer mixture composition and a constant composition of the arising copolymer was achieved. From the analytically estimated free monomers and arising copolymer compositions, the reactivity ratios for the pair AN/BA r₁₂ = 0.71, r₂₁ = 1.17 and for the pair AN/Sty r₁₃ = 0.06, r₃₁ = 0.28 were calculated. The applicability of the reactivity ratios found was verified also for the ternary system acrylonitrile/butyl acrylate/styrene.     

Organotin polymers. IV. Binary and ternary copolymerizations of tributyltin acrylate and methacrylate with styrene,allyl methacrylate,butyl methacrylate,butyl acrylate,and acrylonitrile

The monomer reactivity ratios for the copolymerization of tributyltin acrylate with styrene and allyl methacrylate have been found to be r₁ = 0.213, r₂ = 1.910 and r₁ = 0.195, r₂ = 2.257, respectively. Also, the copolymerization parameters of tributyltin methacrylate with styrene and allyl methacrylate were as follows: r₁ = 0.256, r₂ = 1.104 and r₁ = 2.306, r₂ = 1.013. Copolymerization reactions were carried out in solution at 70°C using 1 mole % AIBN, and the copolymer compositions were determined by tin analysis. Ternary copolymerization of the three systems butyl methacrylate–tributyltin methacrylate–acrylonitrile, butyl acrylate–tributyltin methacrylate–acrylonitrile, and styrene–tributyltin acrylate–acrylonitrile have been studied, and the terpolymer composition of each system was determined through tin and nitrogen analyses. The variation of instantaneous and average terpolymer composition with conversion fit satisfactorily the experimental results over a wide range of conversion.     

丙烯腈/N-乙烯基吡咯烷酮共聚物结构和热解反应表观活化能

引　言共聚单体的选择对碳纤维前驱体聚丙烯腈(ＰＡＮ)原丝性能的影响很大 ,利用丙烯腈 (ＡＮ )共聚纤维进行预氧化可以减少放热量 ,缓和放热反应 .日本特许公报 4 8 2 8986曾报道过 ,由丙烯腈 /Ｎ 乙烯基吡咯烷酮 (ＡＮ/Ｎ ＶＰ)共聚物最终得到的碳纤维强度可达 680 0ＭＰａ .国内外关于丙烯腈共聚物的热解反应的研究早有不少报道[1～ 5] ,但其研究一般是在Ｎ2 气氛下利用间歇性方法进行的 ,难于实时跟踪随实验条件微小改变导致聚合物结构与性能所发生的细微变化 ,实验条件同碳纤维前驱体ＰＡＮ原丝预氧化条件很难统一起来 ,对ＰＡＮ原丝的…     

纤维素醋酸酯接枝己内酯的聚合研究

以冰醋酸为溶剂,浓硫酸为催化剂,将取代度为2 4的二醋酸纤维素水解为取代度为1 4的醋酸纤维素(CA)。以此醋酸纤维素为接枝骨架,ε 己内酯(ε CL)为接枝单体,在辛酸亚锡的引发下,合成了醋酸纤维素/聚己内酯接枝共聚物(CA g PCL)。研究了反应物纯度、原料配比、引发剂与单体摩尔比、反应时间、反应温度对单体转化率(C%)、接枝率(G%)、接枝效率(GE%)的影响。结果表明,当反应温度为140℃,单体ε 己内酯与醋酸纤维素的质量比为4∶1,引发剂辛酸亚锡与单体ε 己内酯的摩尔比为0 005,反应时间为16h,C%,GE%和G%分别为46 8%,65 2%和122 1%。     

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。     

ARGET ATRP法合成聚氯乙烯接枝丙烯酸丁酯共聚物

以不稳定氯含量高的聚氯乙烯（U-PVC）和氯乙烯-溴代异丁酸烯丙酯共聚物（PVC-co-ABrMP）为大分子引发剂,使用电子转移催化再生原子转移自由基聚合（ARGET ATRP）进行丙烯酸丁酯（BA）的溶液接枝共聚。在固定CuCl₂：三（2-吡啶甲基）胺：辛酸亚锡（摩尔比）时,当CuCl₂用量（相对于氯乙烯链节数）小于0.1%时,BA转化率随CuCl₂用量增加而明显增加;辛酸亚锡与CuCl₂摩尔比大于50时,辛酸亚锡用量对聚合速率的影响较小;相同催化体系用量下,采用PVC-co-ABrMP为引发剂,可获得更高的BA转化率。通过PVC-co-ABrMP酯基水解得到PBA支链,其分子量分布指数为1.29,符合“活性”自由基聚合的特征。接枝PBA对PVC有明显的内增塑效果,PBA摩尔分数为32.75%的PVC-g-BA的玻璃化温度为8.34℃。