Toughened polystyrene containing high cis-1,4-polybutadiene rubber

High cis -1,4 -polybutadiene has been used to prepare toughened polystyrene in an attempt to improve its low temperature impact properties. A range of physical and mechanical properties was obtained by keeping the amount of rubber and the polymerization conditions constant, and varying the rate of agitation in a purpose -built reactor system. Although a good balance of tensile and impact properties is obtained at room temperature, the rubber partially crystallizes when the polyblends are cooled to below ?40°C. This should decrease the efficiency of rubber particles to create and terminate crazes. However, it is significant that the developed crystallinity decreases with the rubber phase volume, and is suppressed almost completely at about 21% rubber phase volume (RPV). The factors influencing the RPV are discussed, and a study of the phase inversion with three different types of rubber shows that its duration depends on the viscosity of the styrene/rubber system.     

钼系1,2-聚丁二烯与顺丁橡胶、丁苯橡胶流变性能的比较

采用乌氏黏度计、凝胶渗透色谱仪和RH 2000型双筒毛细管流变仪分别测试了钼系1,2-聚丁二烯(PB)、顺丁橡胶(BR)、溶聚丁苯橡胶(SSBR)和乳聚丁苯橡胶(ESBR)胶料的分子参数和流变性能。结果表明,钼系1,2-PB的数均分子量和特性黏数高于BR、ESBR和SSBR,分子量分布较BR和ESBR宽,SSBR的凝胶含量最高;钼系1,2-PB的流变性能优于其他3种胶料,易于加工。     

环氧化顺丁橡胶与NaHSO3反应制备磺化顺丁橡胶离聚体

研究了环氧化顺丁橡胶溶液在以四乙基溴化铵为相转移催化剂、N,N-二甲基苯胺为开环催化剂的条件下,与NaHSO3的水溶液反应制备磺化顺丁橡胶离聚体.结果表明:该离聚体的磺化度可达到1.77 mmol/g;随着离聚体离子含量的增加,吸水率增加,吸油率降低,离聚体稀溶液的黏度增加,表明了离子基团的存在.     

Equation of state of cis-1,4-polybutadiene melt

Recent equation of state data are analyzed in terms of the hole theory of polymer melts. The good agreement between experimental and theoretical volume-temperature curves at atmospheric pressure, observed previously for a number of amorphous and crystallizable polymers, is again confirmed. Similarly, satisfactory theoretical results for the isotherms ensue, with deviations however becoming noticeable at elevated pressures and low temperatures. The linearity of the isochores observed experimentally is confirmed by the theory, however with somewhat different slopes. Departures of maximally 10 percent from the thermal pressure coefficients derived from the experimental PVT data are noted. Significant differences between theory and experiment apper only in the third derivatives of the partition function, as has also been observed with other pollymers. The characteristic scaling parameters of volume, temperature and pressure show the expected similarity with hevea rubber. Earlier correlations for scaling entropy and segmental volume with scaling temperature are found to be valid within the scatter of these relations. Finally, the applicability of the empirical Tait equation in the form applied to the equation of state in other polymer melts is confirmed. Although the resulting thermal pressure coefficient exhibits an explicit even if smal dependence on temperature, in disagreement with experiment or theory, the Tait equation remains a useful relation for the representation of PVT information.     

Interaction of n-alkanes with crosslinked cis-1,4-polybutadiene

Permeation of n-alkanes through cis-1,4-polybutadine crosslinked using conventional, efficient, and peroxide vulcanizing systems was studied by a gravimetric method. Four alkanes from n-hexane to n-nonane were used. In n-octane, the studies were conducted in the temperature range of 27–70°C.The sorption data was used to estimate the diffusion and permeability coefficients, the activation energy for diffusion and permeation, the entropy and enthalpy of sorption, polymer–solvent interaction parameter, and the degree of crosslinking. The various parameters estimated indicate that permeability of the membranes depends more on the degree of crosslinking than on the nature of crosslinks. Increase in permeant chain length was found to lower permeability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2404–2413, 2001     

氯酯化顺T橡胶的基本性能

将顺丁橡胶胶液与次氯酸叔丁酯及甲酸反应,制得了舍氯和酯侧基的氯酯化顺丁橡胶(CEBR).研究了CEBR生胶的热稳定性能、玻璃化转变温度及门尼黏度,并测定了其硫化胶的力学性能.结果表明,随着结合氯质量分数的提高,CEBR的热稳定性逐渐降低,门尼黏度和玻璃化转变温度上升;CEBR的硫化速率低于顺丁橡胶,且结合氯质量分数越高,硫化速率就越小.必须使用超速硫化促进剂;氯和酯侧基的引入提高了分子的极性,破坏了分子链的规整性,CEBR为非结晶性橡胶;随着结合氯质量分数的增加,CEBR硫化胶的拉伸强度和耐油性提高,且用20份和50份炭黑增强CEBR.当氯的质量分数为3%时,CEBR硫化胶的扯断伸长率可达200%以上.     

Time-dependent viscoelastic functions for cis-1,4-polybutadiene melts

Summary Relevant recent advances in slit die rheometry are discussed, and an error in the cited publication is corrected.     

Time-dependent viscoelastic functions for cis-1,4-polybutadiene melts

Summary Transient linear and nonlinear viscoelastic functions were measured on cis-1,4-polybutadiene melts and compared to the ROUSE theory and a nonlinear modification of the network theory. The latter was found to overestimate material nonlinearity, especially of the first normal stress coefficient at cessation of steady shear flow. Steady-state functions were recovered from the time dependent measurements. Single step strain experiments in the linear region were recorded by computer, up to 7 milliseconds after the sudden shear jump; a paradox arised in the interpretation of shear versus normal stress after a sudden shear strain.Financial support from DEUTSCHE FORSCHUNGSGEMEINSCHAFT and FONDS DER CHEMISCHEN INDUSTRIE is gratefully acknowledged. We thank CHEMISCHE WERKE HÜLS AG for providing the cis-1,4-polybutadienes. Finally, we are especially indebted to Dr. Michael KOWALSKI for intensive cooperation with ELECTRONICS.     

顺丁橡胶用量对官能化溶聚丁苯橡胶/顺丁橡胶

考察了顺丁橡胶用量对官能化改性溶聚丁苯橡胶与顺丁橡胶并用作为胎面胶时的硫化特性、加工性能、物理机械性能及动态力学性能的影响。结果表明,随着顺丁橡胶用量的增加,并用胶的网络化程度增强,硫化进程加快,填料的分散性得以提高,但其静态力学和动态力学性能均有一定程度的损失,其中顺丁橡胶用量为20份（质量）时官能化改性溶聚丁苯橡胶的抗湿滑性能降低了50%左右。     

Effect of long branching and strain-induced crystallization of cis-1,4-polybutadiene observed in nonlinear viscoelastic behavior

The effect of long branching on the deformational behavior has been examined for four commercial high cis-polybutadienes with particular interest as to its implication on their processability. The techniques used were oscillatory shear measurements at small deformation and tensile stress-strain measurements at large deformation. In the shear measurements (linear behavior), the temperature dependence of the shift factor in the time-temperature superposition is related to the degree of branching obtained from dilute solution viscosity. In the tensile measurements (nonlinear behavior), the rubbers showed either strain-hardening or strain-softening. The difference was not related to the degree of branching determined by dilute solution viscosities. This means that the dilute solution viscosity is not an adequate means to explain the processability difference of the rubbers. The branch length, although the absolute value is unknown, is characterized as short or long on the basis of the strain-softening or strain-hardening behavior. Both small shear and large elongational measurements are necessary for characterization of branching pattern and processability. Rubbers with relatively short branches (strain-softening type) or with the smallest amount of long-branching (non-strain-hardening type) were found to strain-crystallize most easily. The absence of strong resistance to stretching is the apparent reason for the ease of crystallization. © 1996 John Wiley & Sons, Inc.     

Measurement of the PVT behavior of cis-1,4-polybutadiene

The volume of cis-1,4-polybutadiene between 5 and 55°C and 1 and 3000 atmospheres was measured to within a relative error of 0.1 percent with an especially developed, bellows-type dilatometer. The presence of a small transition near 55°C was indicated by analysis of the data and confirmed by differential thermal analysis.     

Thermal crosslinking of cis-1,4-polybutadiene at ultrahigh pressures

cis-1,4-Polybutadiene (BR) samples, in the absence of crosslinking agents, were simultaneously compressed by ultrahigh pressures (>4.0 GPa) and annealed between 25 and 180°C. The BR samples were crosslinked when the annealing temperatures were above 100°C. The Vickers microhardness of the treated BR increased and the extent of swelling decreased rapidly as the annealing temperature increased, indicating that the crosslinking density increased. Solid-state carbon-13 nuclear magnetic resonance and Fourier transform infrared spectroscopy results showed that some C=C bonds in the BR were opened to form the crosslinking network structures with C—C linkages and that a partial cis–trans isomerization took place during the treatments. Differential scanning calorimetry studies revealed that the glass transition temperature increased and the crystallinity decreased as the annealing temperature increased. When the annealing temperature exceeded 140°C, the treated BR samples lost their rubbery elastic characteristics completely and became brittle materials. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2131–2140, 1998     

氯化顺丁橡胶的合成及基本性能

在300t/a氯化顺丁橡胶装置上利用顺丁橡胶和氯化剂合成出氯化顺(CBR）以及不同反应时间，碱胶比和碱浓度对氯化反应的影响，研究了CBR胶液的流变特性和CBR的基本性能。     

s-PB/TPI釜内原位聚合共混物的非等温结晶动力学

采用2种负载型催化体系在反应釜内原位合成了间同聚丁二烯（s-PB）及s-PB/反式-1,4-聚异戊二烯（TPI）（80/20）共混物。用DSC方法研究了s-PB及共混物的非等温结晶行为,结果表明：Jeziorny修正的Avrami法和Mo法对s-PB及s-PB/TPI（80/20）共混物的非等温结晶行为有较好的适用性,Ozawa法则存在一定的缺陷。s-PB及其共混物的结晶活化能分别为-253 kJ/mol和-310 kJ/mol。TPI的加入降低了s-PB的结晶速率,使得共混物的结晶活化能绝对值增大。     

稀土顺丁橡胶的性能和应用

介绍了稀土钕系顺丁橡胶(NdBR)的牌号、质量指标、结构参数和性能特点,总结了NdBR在轮胎方面的应用效果,并展望了NdBR的发展前景.     

壬基酚聚氧乙烯醚接枝顺丁橡胶的研制

探讨以过氧化二异丙苯为引发剂，壬基酚聚氧乙烯醚(环氧乙烷分子数为10)为接枝物，采用熔融混炼法制备壬基酚聚氧乙烯醚接枝顺丁橡胶的最佳因子组合。结果得出，熔融混炼法制备壬基酚聚氧乙烯醚接枝顺丁橡胶的最佳因子组合为：壬基酚聚氧乙烯醚用量2份，过氧化二异丙苯用量3份，反应温度150℃，反应时间4min；壬基酚聚氧乙烯醚接枝顺丁橡胶的润湿性显著优于BR。     

顺丁橡胶溶液的分离技术进展

简述了国内外顺丁橡胶溶液的釜式凝聚，塔式凝聚，直接干燥法和相分离法等的发展概况。     

顺丁橡胶装置回收单元的改造

介绍了顺丁橡胶装置丁二烯回收单元的技术改造情况,改选后回收单元处理能力提高５８．５％,能耗降低１０．６４％,回收丁二烯可直接作为丁苯聚合的单体。     

合成顺丁橡胶用稀土催化剂的开发进展

介绍了稀土催化剂聚合丁二烯的反应特征和组成特点,分析了催化剂的制备方法和催化剂活性中心的生成过程,并介绍了窄相对分子质量分布聚丁二烯的合成方法,指出了稀土催化剂的研究方向.     

Head-to-head polymers: 19. Chlorination of cis-1,4-polybutadiene

Chlorination of cis-1,4-polybutadiene (PB) has been studied in detail. It was found that chlorination must be carried out in an oxygen free atmosphere at polymer concentrations below 0.5%, and at temperatures below room temperature in mixed solvents with dichloromethane as the major component. In the initial stage of chlorine addition to the double bonds of cis-1,4-polybutadiene, block structures of chlorinated segments are formed. The chlorine addition to the cis-butadiene units was not stereospecific and the final chlorination product had nearly a 1:1 ratio of the threo- and erythro structure of the CHCICHCI-units. Microphase separation in partially chlorinated PB was observed by d.s.c., dynamic-mechanical measurement, and transmission electron microscopy. It was concluded that partially chlorinated PB, whose degree of chlorination was lower than 65 mole %, was composed of almost pure cis-1,4-PB domains and a separate phase which consists ofCH₂CHCICHCICH₂units with perhaps as much as 10% of cis-1,4-PB units incorporated in this phase. If the degree of chlorination is more than 90 mole % one phase exists.