Oxidation behavior of isoprene polymers and butadiene polymers

The oxidation behavior of cis-1,4-polyisoprene, emulsion polyisoprene, emulsion isoprene/styrene copolymers, and emulsion butadiene/styrene copolymers by heat aging or ultraviolet irradiation has been investigated from the change of gel fraction and molecular weight distribution. It was determined that the oxidation behavior of both isoprene and butadiene polymers is strongly dependent on the composition of the polymers as well as on the microstructure of the polymers. In the case of oxidation by heat aging, the probability ratio of chain scission to crosslinking of both isoprene and butadiene copolymers increases gradually with increasing styrene fraction. In the case of oxidation by ultraviolet irradiation, isoprene copolymers show a remarkable increase in the probability ratio of chain scission to crosslinking, whereas butadiene copolymers show substantially no change with increase in styrene fraction. It was also demonstrated that both isoprene and butadiene polymers show a greater tendency for crosslinking with oxidation by ultraviolet irradiation than with oxidation by heat aging.     

氮官能化多锂引发丁二烯/异戊二烯/苯乙烯聚合动力学

以自制氮官能化多锂(以下简称Li)为引发剂,N,N,N′,N′-四甲基乙二胺(TMEDA)为极性调节剂,环己烷为溶剂,对苯乙烯(St)、异戊二烯(Ip)、丁二烯(Bd)进行负离子聚合,合成了星形集成橡胶丁二烯-异戊二烯-苯乙烯三元共聚物(SIBR),研究了不同TMEDA/Li(摩尔比)下SIBR的聚合反应动力学。结果表明,在三元共聚合反应中,3种单体的反应速率与其各自浓度均符合一级动力学关系;在SIBR的合成体系中,随着TMEDA/Li的增大,Bd的反应速率常数先升高后降低,St的反应速率常数逐渐增加,Ip的反应速率常数逐渐降低;当TMEDA/Li为1·0、二乙烯基苯(DVB)/Li(摩尔比)为0·8、引发剂浓度为7·69×10-4mol/L时,单体Bd,Ip,St的表观增长反应活化能分别为31·59,47·64,31·76kJ/mol,链增长频率因子分别为1·02×104,1·09×106,5·27×103min-1。     

苯乙烯/异戊二烯/丁二烯(S/I/B)星型嵌段聚合物的研制方法

介绍了近年来的苯乙烯／异戊二烯／丁二烯（S／I／B）星型嵌段聚合物的发展与研制方法。重点评述了星型嵌段聚合物SIB、IB、IBI、SIS的研制方法，提出应用阴离子聚合方法合成星型聚合物的巨大潜力以及目前的任务。     

Preparation and characterization of carboxylated isoprene/styrene copolymer latexes

Carboxylated isoprene/styrene copolymer latexes were prepared, and the concentration of surface carboxyl groups and the freeze–thaw stability of these latexes were measured. It is clarified that the introduction method of the carboxylic monomer governs the distribution of carboxyl groups in latex particles. Introduction of the carboxylic monomer prior to the initiation of polymerization localizes only 12–13% of total carboxyl groups on the surface of particles, whereas introduction of the carboxylic monomer at the last stage of polymerization localizes more than 60% of total carboxyl groups on the surface of particles, though the percentage is strongly dependent on the conversion when the monomers are shot. These latexes show a remarkable increase in the freeze–thaw stability with the increase in the degree of neutralization of surface carboxyl groups in a fairly narrow range. There exists a linear relationship between the surface area occupied by a surface carboxyl group and the degree of neutralization of surface carboxyl groups at which the remarkable increase in the freeze–thaw stability is observed. The result suggests that the freeze–thaw stability is substantially determined by the density of carboxylate ion on the surface of particles.     

Blends of styrene butadiene styrene TRI block copolymer/polyaniline-Characterization by WAXS

Electrically conductive blends based on polyaniline-dodecylbenzene sulphonic acid (Pani.DBSA)/styrene-butadiene-styrene (SBS) block copolymer have been prepared by two methods namely melt mixing and polymerization of aniline in the presence of SBS using in situ polymerization method. The influence of composition and synthetic methods on the performance of SBS/Pani blends was established. The obtained SBS/Pani blends have been characterized by mechanical, morphological and electrical properties. A great reduction in volume resistivity values with increase in Pani content was noticed for in situ polymerization method compared to melt mixing method. The microstructural parameters were also computed using Wide Angle X-ray Scattering (WAXS). The results are compared with mechanical and electrical properties.     

对称型双端过渡态丁二烯/苯乙烯嵌段共聚物的性能研究

采用以双卤代烷烃取代型双锂齐聚物为引发剂、环己烷为溶剂、丁二烯 (B)、苯乙烯 (S)单体一次加入的方法 ,合成了对称型双端过渡态丁二烯 /苯乙烯嵌段共聚物S— (S/B)—B— (B/S)—S ,并对其性能进行了研究。结果表明 ,对称型双端过渡态丁二烯 /苯乙烯嵌段共聚物具有明显的海岛两相结构 ,嵌段共聚物存在两个玻璃化温度 ;随着单体配比 (质量比 )S/B的增大 ,嵌段共聚物的各项物理性能变化趋势不明显。     

对称型双端过渡态丁二烯／苯乙烯嵌段共取的性能研究

采用以双卤代烷取代型双锂齐聚物为引发剂、环已烷为溶剂、丁二烯（B）、苯乙烯（S）单体一次加入的方法，合成了对称型双端过渡成丁二烯／苯乙烯嵌段共聚物S－（S／B）－B－（B／S）－S，并对其性能进行了研究。结果表明，对称型双端过渡态丁二烯／苯乙烯嵌段共聚物具有明显的海岛两相结构，嵌段共聚物存在两个玻璃化温度；随着单体配比（质量比）S／B的增大，嵌段共聚物的各项物理性能变化趋势不明显。     

Relating microhardness to morphology in styrene/butadiene block copolymer/polystyrene blends

The microhardness behaviour of binary blends comprising a styrene/butadiene star block copolymer and polystyrene homopolymer (hPS) over a wide composition range is investigated. In particular, the interrelation between the morphology, tensile properties (such as yield stress σ_Y and the Young's modulus, E) and the microhardness H is explored. As in the case of microphase separated block copolymers and binary block copolymer blends, as reported in preceding publications, a clear deviation in the microhardness behaviour from the additivity law is observed. The lamellar block copolymer system is compared with the nanostructure of semicrystalline polymers having a lamellar morphology. A dependence of H upon PS lamellar thickness is found. For the samples with lamellar morphology the hardness value was found to correlate with the mechanical parameters obtained by uni-axial tensile testing according to: H/σ_Y∼2.2 and E/H∼22.     

Microhardness of styrene/butadiene block copolymer systems: Influence of molecular architecture

The influence of molecular architecture on the mechanical properties of styrene/butadiene block copolymers was investigated by means of the microhardness technique. It was found that the microhardness of the styrene/butadiene block copolymers is dictated by the nature of microphase separated morphology. In contrast to polymer blends and random copolymers, in which the microhardness generally follows the additivity rule, the behavior of the investigated block copolymers was found to significantly deviate depending on their molecular architecture. The glass‐transition temperature of the polystyrene phase (T_g‐PS), which practically remained constant and that of the polybutadiene phase (T_g‐PB), which varied with the change in the block copolymer architecture, apparently do not influence the microhardness values of the block copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1670–1677, 2003     

电脱水技术在氢化苯乙烯/异戊二烯共聚物胶乳脱水中的应用

考察了电脱水温度及压力、乳胶上升速率、电场强度对氢化苯乙烯/异戊二烯共聚物（SEPS）胶乳脱水效果的影响。结果表明,SEPS胶乳电脱水的最佳条件为:操作温度75～85 ℃,胶乳上升速率2 cm/min,电场强度800～1 000 V/cm。经电脱水技术脱水的SEPS胶乳含水质量分数小于1.5%。     

Effect of liquid isoprene rubber on dynamic mechanical properties of emulsionpolymerized styrene/butadiene rubber vulcanizates

The effect of liquid isoprene rubber (LIR) on the dynamic mechanical properties of emulsion‐polymerized styrene/butadiene rubber (ESBR) vulcanizates was investigated by temperature sweep using dynamic mechanical analysis. The introduction of LIR led to ESBR vulcanizates having higher loss factor (tan δ) in the temperature range ? 30 to 0 °C, and lower tan δ in the range 60 to 80 °C. A small amount of LIR‐403 (LIR with carboxyl groups) led to a significant change in tan δ: the addition of LIR‐403 (3 phr) led to a 7.5% increase in tan δ from ? 30 to 0 °C, and a 24.9% decrease in tan δ from 60 to 80 °C. It was found that the introduction of LIR increased the bound rubber content in the ESBR compound. Equilibrium swelling experiments showed that the crosslink density of the vulcanizates increased after the introduction of LIR‐403 or LIR‐50 (general purpose LIR). The change in tan δ from 60 to 80 °C was related to polymer–filler interactions. The characteristic constant of filler–ESBR matrix interaction (m) was calculated. At a given filler volume fraction, the increase in m in the presence of LIR could be well related to the decrease in tan δ from 60 to 80 °C. The influence of LIR on filler network in the ESBR compound was also investigated by strain and temperature sweeps using a rubber processing analyzer. Copyright © 2011 Society of Chemical Industry     

高反式- 1,4-丁二烯-异戊二烯共聚物

综述了国内外合成高反式－1，4－丁二烯－异戊二烯共聚物的配位催化体系，负离子催化体系，醇（钠）烯催化体系及其共聚物的结构与性能，用核磁共振，红外光谱对其进行了表征，并提出了发展建议。     

丁苯嵌段共聚物的催化氢化研究进展

介绍了丁苯嵌段共聚物的催化加氢技术，综述了茂金属催化剂，环烷酸镍（钴）催化剂，三苯基膦-氯化钌（铑），铁钴镍螯合物均相催化剂及非均相催化剂的技术进展。讨论了氢化丁苯嵌段共聚物氢化度的定性分析和定量分析方法。     

官能化丁苯渐变嵌段共聚物树脂的合成与表征

采用溶液聚合法,以官能化偶联剂合成了带有HN-,HO-,HS-的官能化丁二烯-苯乙烯渐变嵌段共聚物.结果表明,该聚合物为单形态的三臂或四臂星形共聚物,具有良好的透光率和耐环境开裂性以及较好的耐氧化性、耐热性和表面粘接性,可应用于医疗器械、儿童玩具、食品容器等行业.     

Functionalization of a styrene/butadiene random copolymer by radical addition of l-cysteine derivatives

The functionalization of a styrene/butadiene (20/80) random copolymer (SBR) is performed by radical-mediated addition of l-cysteine derivatives to the macromolecules' double bonds. The reaction carried out in solution and in the melt leads to SBR chain bearing amino and carboxylate functionalities through thiol addition to the vinyl double bonds of the 1,2-butadiene units with anti-Markovnikov regioselectivity. The addition yield (up to 5 wt%) and the occurrence of the crosslinking side reaction are investigated with reference to feed conditions and process parameters. The optical rotation of the reaction products confirms the addition of l-cysteine to SBR chain and provides a simple route to prepare optically-active polymers containing pendant amino acid residues.     

Deformation behaviour of styrene/butadiene star block copolymer/hPS blends: influence of morphology

The influence of morphology on micromechanical deformation behaviour of blends consisting of a lamellar forming styrene/butadiene star block copolymer and polystyrene homopolymer (hPS) was studied by transmission electron microscopy (TEM). The pure star block copolymer and the microphase separated blends revealing lamellar structure with polystyrene (PS) lamella thickness in the range of about 20 nm showed homogeneous plastic deformation of the PS lamellae. The macrophase separated blends with PS particles in lamellar matrix exhibited debonding at the particle–matrix interface associated with extensive plastic deformation of the surrounding matrix. The blends containing PS matrix deformed via crazing.     

丙烯腈-丁二烯-苯乙烯树脂改性用丁苯嵌段共聚物的合成

以正丁基锂为引发剂、环己烷为溶剂、四氢呋喃为调节剂,在模试装置上合成了丙烯腈-丁二烯-苯乙烯(ABS)树脂改性用橡胶——丁苯嵌段共聚物,研究了反应温度与产品支化结构含量、相对分子质量与产品门尼黏度、凝胶质量分数、微观结构含量的关系。结果表明,随着聚合反应最高温度的升高,共聚物支化结构含量增大;当引发温度为55℃、反应最高温度为110～120℃时,产品支化结构含量约为5%,分子量分布约为1.12,其凝胶质量分数、微观结构含量与目标产品一致,丁苯嵌段共聚物的各项性能实测值符合ABS树脂改性用胶要求。     

Ionomer composites based on sepiolite/hydrogenated poly(styrene butadiene) block copolymer systems

Ionomeric composites based on sepiolite and hydrogenated poly(styrene butadiene) block copolymer were obtained and characterized from a microstructural and electrical point of view. Before blending, because of the high silanol group concentration in the sepiolite, the latter could be organophilized with suitable coupling agents. The resulting materials were easily processed into thin films or membranes 0.2–0.4 mm thick, their conductivity in some cases approaching 10^?1 S/cm. Their suitability for film formation and good electrical properties indicate potential applications as electrolytes in polymer fuel cells. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3512–3519, 2002     

Phase separation in blends of homopolymer and graft copolymer based on styrene and butadiene

A series of blends of homopolystyrene and styrene-g-butadiene copolymer with different combinations of molecular weights of the copolymer and graft polystyrene segments have been prepared. Phase separation behaviour of the blends has been examined by electron microscopy. The results reveal a regular change of morphology of the blends with the relative molecular weights of the free and graft polystyrene chains. The observed relationships between compatibility of the homopolymer and copolymer and the relative molecular weight are generally in agreement with that observed previously in homopolymer-block copolymer blends. Taking the inherent polydispersity of the molecular weight of the component polymers into account, some peculiarities of the morphologies of the blends have been explained.     

Preparation and stress–strain properties of ABA-type block polymers of styrene and isoprene or butadiene

Several series of ABA-type “tapered” block polymers of styrene (monomer A) with isoprene or butadiene were prepared with the use of n-butyllithium or sec-butyllithium as initiators in benzene solution. The stress-strain curves of the raw polymers are reported, showing that many of them behave at ambient temperature like vulcanized elastomers. These polymers consist, however, of completely linear chains, with no chemical crosslinks between them; they are thermoplastic, can be easily molded, and are soluble in common solvents. Hence, they may be classed as pseudo-crosslinked elastomers. Better stress-strain properties are obtained from polymers made with sec-butyllithium than with n-butyllithium; in turn, polymers from butadiene have better properties than those from isoprene. Stress–strain curves most closely resembling those of crosslinked elastomers are obtained in general from polymers containing about 30–45% styrene. It was found that AB-type block polymers have very poor tensile strengths and low elongations. The microstructures of polybutadienes and polyisoprenes of various molecular weights, prepared in benzene solvent with alkyllithium initiators, were also determined and compared with literature data for like polymers prepared in cyclohexane solvent.