Synthese und charakterisierung von butadien-divinylbenzol-copolymeren

The copolymerization of butadiene with a technical divinylbenzene fraction was investigated to study the modification of cis-1,4 polybutadiene. Beside the Ziegler-Natta-catalyst nickeloctanoate/bortrifluoride/aluminiumtriethyl, another catalytic system consisting of nickeloctanoate/titaniumtetrachloride/aluminiumtriethyl was used, which allows to polymerize more divinylbenzene because of its higher activity toward vinylaromates. With the help of spectroscopical, pyrolysis-gaschromatographical and thermoanalytical methods one can obtain relations between glass-, crystallization- and melting temperature and the microstructure of the polymer. It can be shown that not only the divinylbenzene but also the trans-1,4- and the 1,2-vinyl units are statistically distributed in the polymer. By this, beside the pyrolysis-gaschromatography, particularly the differential scanning calorimetry is a useful tool to characterize the structure of partially crosslinked polymers obtained from polymerization of technical fractions.     

钴系催化剂合成液体聚丁二烯过程中α—烯烃的调节作用

以环烷酸钴、三异丁基铝和三氯甲苯为催化剂,抽余油作溶剂,乙烯、丙烯和异丁烯为分子量调节剂,合成了顺式1,4含量为45—60%、反式1,4含量为10—40%、乙烯基含量为15—40%、数均分子量为1500—6000的液体聚丁二烯,考察了α-烯烃用量等因素对转化率、分子量及产物微观结构的影响.对α-烯烃的调节机理作了探讨.     

聚丁二烯橡胶接枝苯乙烯本体自由基聚合机理

采用傅里叶变换红外光谱法和碘值法分析了在热引发和化学引发方式下,低顺式和高顺式聚丁二烯橡胶接枝苯乙烯聚合物的双键结构和含量,确定了橡胶接枝苯乙烯本体自由基聚合机理。结果表明,热引发时,接枝机理主要是自由基夺取橡胶链上α氢原子;而化学引发时,同时存在自由基与橡胶双键加成的机理。橡胶的结构不同导致接枝点的位置差异,在低顺式聚丁二烯橡胶体系中,自由基以夺取反式-1,4-结构和1,2-乙烯基结构为主,而在高顺式聚丁二烯橡胶体系中。自由基以夺取顺式-1,4-结构为主。     

均相稀土催化苯乙烯均聚及其与异戊二烯共聚

采用新型稀土催化体系氯代三氟乙酸钕－烷基铝－卤代烃,引发苯乙烯均聚及其与异戊二烯共聚。 催化体系各组分及陈化方式、Ｘ和Ａｌ种及用量,溶剂种类等因素对苯乙烯聚合的影响,并用稀土催化实现了Ｓｔ－Ｉｐ嵌段共聚。用ＩＲ,ＮＭＲ及ＤＳＣ等方法表征了聚合物的结构,合成出的Ｓｔ－Ｉｐ二嵌段共聚物中,Ｉｐ链节以反式－１,４－结构为主,含少量３,４－结构,几科不含顺式－１,４－结构。     

钛系催化剂合成聚异戊二烯橡胶的研究进展

利用钛系催化剂合成的异戊橡胶具有与天然橡胶媲美的性能。本文介绍了聚异戊二烯的不同结构和国内外异戊橡胶的生产状况,综述了钛系催化剂的制备方法、聚异戊二烯的聚合动力学及其对微观结构中顺式含量的主要影响因素,并对钛系异戊橡胶的研究与发展前景进行了展望,发现开发廉价的钛系催化剂是合成异戊橡胶的必然趋势,发展钛系高顺式聚异戊二烯应是合成高顺式聚异戊二烯工业的首选,同时还提出了合成顺式聚异戊二烯的研究中存在及有待改进的一些问题。     

6-取代-l,4-环辛二烯的单重态氧反应——合成顺式-5,8-和反式-5,6-二取代-1,3-环辛二烯含氧衍生物的方便途径

以竹红菌甲素作敏化剂匹配高压钠灯产生单重态氧,在甲醇溶液中,氧化6-取代-1,4-环辛二烯(1),(2),并经亚硫酸钠还原,得到顺-5,8-二取代-1,3-环辛二烯和反-5,6-二取代-1,3-环辛二烯发。化合物(3)是在三氯乙烷溶液中,未经还原得到过氧化氢基取代-1,3-环辛二烯。基态分子的稳定构象决定了反应产物的立体选择性。这类反应为用光氧化方法合成顺-5,8-二取代和反-5,6-二取代-1,3-环辛二烯含氧衍生物提供了方便的途径。     

低温预制钛系催化剂合成cis-1,4-聚异戊二烯

采用Ziegler-Natta配位聚合制备了高顺式聚异戊二烯,主要考察了非均相催化体系四氯化钛-三异丁基铝二组分催化剂的预制方法以及催化剂预制条件对异戊二烯体系聚合规律的影响。讨论了催化剂配比、预制催化剂温度和陈化温度对催化剂活性及聚合物的凝胶含量、特征黏度、微观结构含量等方面的影响。同时讨论了催化剂用量、聚合温度和聚合时间对聚合活性及聚合物的凝胶含量、特征黏度、微观含量等方面的影响。研究结果表明,合成高cis-1,4-聚异戊二烯的最佳实验条件为:Al/Ti摩尔比1.0,催化剂预制温度-40℃,陈化2 h,Ti/Ip摩尔比6×10^-3,聚合温度50℃,聚合时间5 h。所得聚合物最高转化率为87.1%,cis-1,4结构含量为91.76%。     

结构调节剂对液体异戊二烯聚合的影响

采用锂系阴离子聚合工艺合成液体异戊二烯橡胶( LIR),在聚合过程中添加5种不同的结构调节剂,研究他们对LIR结构的影响。结果表明：非极性调节剂二硫化碳(CS₂)对LIR顺-1,4含量的影响不大;极性调节剂均可降低顺-1,4含量。其中二乙二醇二甲醚(2G)、四甲基乙二胺(TMEDA)对顺-1,4含量的调节作用较大;乙醚(Et₂O)对顺-1,4含量的调节作用较小;四氢呋喃(THF)作为结构调节剂效果最好。     

镍系催化剂合成顺丁橡胶的开发研究

回顾了Ｎｉ系催化剂的开发研究及应用。重点介绍Ｎｉ系催化剂合成顺丁橡胶的聚合特征，活性中心模型，聚合机理，聚合动力学，以及国内外改进Ｎｉ系催化剂的新进展。     

Micro- and macroconformation of macromolecules

Summary Thermoelastic data of eis- trans- 1,4- polybutadiene networks swollen in n- octane are presented. On the basis of the theory of the Gaussian chain the analysis of the energy part of the retractive force and of the temperature dependence of the unperturbed dimensions has been carried out as the function of the cis- trans- ratio of the subunits within the macromolecular chains. Temperature invariant macroconformation has been verified by quasi- isoenergetic chains consisting on 40 % trans and 60 % cis- units within statistically arranged cis- trans- polybutadiene networks.Herrn Prof. Dr. G. V. Schulz zu seinem 75. Geburtstag gewidmetProf. Dr. H. A. SCHNEIDER we are obliged for fruitfull discussions. Thanks to Mr. A. HASENHINDEL for technical assistance and Mr. BANDARA for X-ray diagrams. Financial support of DEUTSCHE FORSCHUNGSGEMEINSCHAFT is gratefully acknowledged.     

溶聚丁苯橡胶2557A与5025-2结构和性能的对比研究

采用傅里叶变换红外光谱分析仪、凝胶渗透色谱-激光光散射-自动黏度在线检测仪、动态力学性能分析等手段,对国产溶聚丁苯橡胶(SSBR 2557A)的微观结构及基本性能进行了分析与表征,并与国外丁苯橡胶(SSBR 5025-2)产品作了对比,同时对其在轿车子午线轮胎中的应用性能进行了分析。结果表明,SSBR 2557A顺式含量和反式1,4结构含量几乎相同,而SSBR 5025-2的顺式1,4含量明显大于反式1,4结构含量,两种胶都为高乙烯基含量结构。与SSBR 5025-2相比,SSBR 2557A支化度较低。SSBR 2557A在0℃时的tanδ高达0.779,表明其降低滚动阻力的同时,显著提高了轮胎的抗湿滑性。     

Studies on the Decomposition of Alkyl Hydroperoxides by different catalysts

The catalytic decomposition of cumene, 1-methylcyclohexyl and cyclohexyl hydroperoxides was studied in cyclohexane, cis- and trans-1,4-dimethylcyclohexane and cis-pinane as the solvents. The stearates and the acetylacetonates of manganese, cobalt and chromium, the acetylacetonates of molybdenum and vanadium, n-butyl orthoborate and n-butyl metaborate were used as the catalysts. The chromium-, vanadium-, molybdenum- and boron-containing catalysts brought about some Hock-type decomposition of cumene hydroperoxide and thus proved to be acidic. Of these more of less acidic catalysts only molybdenyl acetylacetonate effected a partially stereospecific hydroxylation of the tertiary C H-bonds in cis- and trans-1,4-dimethylcyclohexane. The well-known selectivity of chromium catalysts for the ketone formation during the decomposition of secondary hydroperoxides is caused by the catalytic oxidatio of secondary alcohols by hydroperoxides in the presence of chromium compounds. In the presence of all the catalysts used the free-radical pathways of the hydroperoxide decomposition predominated, and the attack of the intermediate radicals on the starting hydroperoxide was more important than the attack on the solvent molecules.     

二乙二醇单乙醚基钡/三异丁基铝/多锂体系合成高反式-1,4-聚丁二烯

以二乙二醇单乙醚基钡(简称Ba)/三异丁基铝(简称Al)/多锂(简称MLi)组成的三元引发体系制得了高反式-1,4-聚丁二烯(HTPB),考察了引发体系各组分配比及聚合温度对HTPB反式结构含量及其玻璃化转变温度(T_g)和熔点(T_m)的影响.结果表明,以MLi为引发剂,四甲基乙二胺为极性调节剂,可以得到最大臂数为3.64、平均臂数约为2.50的星形聚丁二烯;当聚合温度为50 ℃、Ba/Al/MLi(摩尔比)为1/4/4时,HTPB的反式结构摩尔分数最高,接近90%;升高聚合温度使聚丁二烯的反式结构摩尔分数下降;当HTPB的反式结构摩尔分数由69.28%增至89.90%时,其T_g上升5～10 ℃,而T_m升高幅度可达30 ℃;随着聚合温度的升高,HTPB的T_g和T_m均下降.     

Selective hydrogenation and isomerization of pentadiene over molybdenum hexacarbonyl encaged in a NaY zeolite

Highly stereo-selective hydrogenation of trans-1,3-pentadiene to cis-2-pentene and isomerization of 1,4-pentadiene to cis-1,3-pentadiene were found to take place thermally at 423 K over Mo(CO)₆/NaY. Relative hydrogenation rates of pentadiene isomers indicated that s-cis conformation of diene was crucial for the selective hydrogenation to occur. This was substantiated by an IR study.     

液体聚异戊二烯的结构表征

通过傅立叶变换红外光谱、核磁共振、不饱和度测定、凝胶渗透色谱、热重分析和动态流变分析等手段对液体聚异戊二烯（LIR-50）的结构及其基本性质进行了研究.结果表明,LIR-50的链节化学组成与天然橡胶完全相同,但二者的空间结构有明显区别.LIR-50的顺-1,4、反-1,4和3,4结构含量分别为70.8%、24.4%、4.8%,而天然橡胶的顺-1,4结构高达98%.LIR-50的数均分子量为42000,多分散指数为1.24,其动态粘度对温度敏感,对剪切速率不敏感.     

The influence of ageing and polymerization conditions on the polymerization of butadiene using a neodymium catalyst system

The homopolymerization of butadiene in the presence of a rare earth-containing catalyst system was examined at 60°C. The catalyst system consists of neodymium octanoate, diethylaluminium sesquichloride and triisobutyl aluminium in n-heptane. This catalyst shows high activity also at low polymerization temperature and yields polymers with a cis-1,4 content of nearly 99%. The catalyst ageing and the polymerization conditions were varied and the behaviour of molar mass distribution, conversion and microstructure of polymers is illustrated. Attention is focussed on molar mass distribution of cis-1,4-polybutadiene samples which can be unimodal or bimodal in dependence on the preparation conditions.     

Using heavy ethers as structure modifiers in the synthesis of SBS block copolymers in cyclohexane

Heavy ethers—diethoxyethane (DIOXO) and triethylorthoacetate (TEOA)—were evaluated and compared with monoethers such as tetrahydrofuran (THF) and diethylether (DEE) as structure modifiers during the synthesis of linear styrene-butadiene block copolymers of polyA-block-polyB-block-polyA type (SBS). A smaller amount of a heavy ether than a monoether was needed to achieve the same targeted content of the 1,2-polybutadiene (vinyl) microstructure. The vinyl content increased from 10 to 71% with increase in the amount of TEOA from 10 ppm to 1 wt %, while the trans-1,4 and cis-1,4 units decreased. Similarly, increasing the amount of DIOXO from 10 ppm to 1 wt % increased the vinyl content from 17 to 89%. TEOA, 300 ppm, or DIOXO, 50 ppm, were suggested for making an SBS copolymer with a targeted 40% vinyl content. The addition of heavy ethers as structure modifiers also increased the rates of polymerization for both styrene and butadiene. Among all ethers, DIOXO enhanced the rate of butadiene polymerization the most, whereas TEOA caused the highest rate of styrene polymerization. Heavy ethers accelerated the rates of polymerization more than did monoethers. Furthermore, for an SBS polymer synthesized via a sequential method, the addition of heavy ethers enhanced the crossover efficiency, resulting in a narrower molecular weight distribution with a lower polydispersity. For an SBS polymer made via a coupling method, the coupling efficiency decreased and varied with the type of the coupling agent used. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2543–2560, 1997     

顺丁橡胶装置丁二烯回收单元的改造

介绍了顺丁橡胶装置丁二烯回收单元的技术改造情况，改造后回收了放火炬燃烧的1．3-丁二烯，其收率可达85％，回收的1，3-丁二烯的质量满足设计要求，并可直接作为顺丁橡胶聚合的单体。     

Radiation induced cis-trans isomerization of swollen polybutadiene networks

Summary The kinetics of the radiation induced cis- trans- isomerization of cis- 1,4- polybutadiene gel swollen in toluene were studied by using diphenyl disulfide as sensitizer. The reaction follows first order kinetics. The values of the pseudo first- order rate constant of the isomerization vary with the crosslink density of the network. After correction for the degree of swelling, however, the isomerization reaction turns out to be independent of the crosslink density and proceeds with the same efficiency as in solution.     

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。