SSBR基本性能的研究

对比研究溶聚丁苯橡胶（SSBR）Buna VSL 5025-2和2438-2HM、乳聚丁苯橡胶（ESBR）1712和1721生胶、混炼胶和硫化胶的基本性能。结果表明：与ESBR1712相比,SSBR Buna VSL 5025-2生胶的加工性能稍差,混炼胶的操作安全性能较好,硫化胶的定伸应力较大,拉伸强度和拉断伸长率较小,抗湿滑性能较好,滚动阻力稍高;与ESBR1721相比,SSBR Buna VSL 2438-2HM硫化胶的滚动阻力较低,其余性能变化趋势和SSBR Buna VSL 5025-2与ESBR1712的变化趋势相似。     

分子结构及炭黑粒子对丁苯橡胶挤出流变特性的影响

本工作主要通过毛细管流变仪,并结合多种表征测试手段,考察了丁苯橡胶分子结构以及炭黑用量对胶料挤出流变特性的影响。结果表明：ESBR1712纯胶及填充胶表观剪切黏度均大于SSBR2564A;ESBR1712与SSBR2564A两种纯胶的挤出稳定性相近,但炭黑填充SSBR2564A混炼胶的挤出稳定性更为优异,挤出物外观质量较好;与SSBR2564A相比,ESBR1712分子链柔顺性更好,炭黑在该体系中的分散性更好,结合胶含量更高。     

溶聚丁苯橡胶T2530基本性能的研究

探讨国产溶聚丁苯橡胶(SSBR)T2530的基本性能.结果表明,与乳聚丁苯橡胶(ESBR)1712E和1712相比,SSBR生胶的重均相对分子质量略小,数均相对分子质量稍大,相对分子质量分布较窄,纯胶含量较高;混炼胶的门尼粘度较高,硫化速度较快,焦烧时间略有缩短,但加工工艺性能差别不大;硫化胶的300%定伸应力和拉伸强度略低(适当调整炭黑用量可使300%定伸应力达到ESBR的水平),弹性较好,滚动阻力较低.     

不同牌号丁苯橡胶的结构与性能对比

对不同牌号丁苯橡胶的微观结构、分子量及其分布、硫化胶的物理机械性能、混炼胶的硫化特性、压缩永久变形及动态力学性能进行了对比.结果表明,溶聚丁苯橡胶(SSBR)与乳聚丁苯橡胶(ESBR)的乙烯基、反式-1,4-结构及顺式-1,4-结构含量差别较大.SSBR的相对分子质量更高,分子量分布更窄,硫化速率更快,耐磨性能、抗湿滑...     

白炭黑填充不同牌号溶聚丁苯橡胶的性能对比

在分析了不同牌号溶聚丁苯橡胶(SSBR 5025-2、72612 S、2564 S)分子结构的基础上,研究了白炭黑填充SSBR硫化胶的物理机械性能、动态力学性能,并用橡胶加工分析仪探讨了白炭黑的网络化结构及其与SSBR的相互作用。结果表明:3种SSBR生胶中,72612 S的相对分子质量最大,分子量分布指数最小,5025-2的相对分子质量最低,分子链柔顺性最好,2564 S的分子链柔顺性最差;3种SSBR硫化胶中,72612 S的拉伸强度和定伸应力最大,扯断伸长率最低,耐磨性最好,滚动阻力最小,抗湿滑性能与2564 S基本相当,而5025-2的回弹性、生热和压缩永久变形最高,耐磨性和动态力学性能最差,三者的撕裂强度和硬度相差不大;白炭黑在72612 S中分散性最好且两者的相互作用最强,而在5025-2中分散性最差,Payne效应强,与橡胶基体的相互作用最弱。     

几种新型胎面用SBR的结构与性能

对比研究乳聚丁苯橡胶(ESBR)和几种溶聚丁苯橡胶(SSBR)的结构与性能.结果表明,ESBR生胶和混炼胶门尼粘度较小,硫化胶的强伸性能和耐磨性能较好,压缩疲劳性能和动态性能较差;SSBR YL950,SSBR2305和SSBR SL552生胶和混炼胶门尼粘度较小,硫化胶的强伸性能、耐磨性能、压缩疲劳性能和动态性能居中;星形SSBR生胶门尼粘度较混炼胶大,加工性能好,硫化胶物理性能、耐磨性能和动态性能达到平衡,适用于"绿色轮胎"胎面胶.     

溶聚丁苯橡胶2557-A的基本性能

对中国石油独山子石化公司生产的溶聚丁苯橡胶(SSBR)2557-A的基本性能进行了研究,并与SSBR T 2530、5025-1以及乳聚丁苯橡胶(ESBR)1712的性能进行了对比。结果表明,相对于ES-BR 1712和SSBR T 2530,SSBR 2557-A的分子量分布较窄,乙烯基含量高;2557-A与SSBR 5025-1的微观结构基本一致;2557-A的拉伸强度和定伸应力均比1712和5025-1低;同1712和T 2530相比,2557-A和5025-1的硬度较高,回弹性很低,压缩生热较低;2557-A的耐磨耗性能低于1712和T2530;相对于1712,2557-A的热氧老化性能较好;2557-A具有优良的抗湿滑性能,滚动阻力较小。     

独山子石化SSBR与同类产品性能对比研究

对比研究了3种溶聚丁苯橡胶的结构及组成,标准配方及不同补强体系下的硫化特性、力学性能、耐磨性能、交联密度.结果表明,标准配方下,三者力学性能、焦烧时间差异不大,SSBR2564S的硫化速率稍慢.炭黑补强体系下,三者的加工操作安全性相当,SSBR2564S、2564A力学性能相当,SSBR2564S耐磨耗性能较好;SSBR5025-2、SSBR2564A的交联密度略高于SSBR2564S.白炭黑补强体系下,SBR2564A、SSBR5025-2硫化特性相当,SSBR2564S、SSBR5025-2力学性能相当,SSBR2564 A耐磨耗性能较好,SSBR2564S的交联密度与SSBR2564A相当.     

溶聚丁苯橡胶2557A的结构与性能研究

研究溶聚丁苯橡胶(SSBR)2557A的结构和性能,探讨其对轮胎胎面胶抗湿滑性能和滚动阻力的影响,并与乳聚丁苯橡胶(ESBR)1712E进行对比。结果表明:与ESBR1712E相比,SSBR2557A的乙烯基含量高,数均和重均相对分子质量大,相对分子质量分布指数小;混炼胶的焦烧时间长,硫化速度稍慢;硫化胶的邵尔A型硬度和定伸应力稍高,拉断伸长率减小,压缩生热和压缩永久变形较低,其他物理性能差别不大,不同应变下的剪切弹性模量、剪切损耗模量和损耗因子(tanδ)均较小,0℃下的tanδ值较大,60℃下的tanδ值较小。采用SSBR2557A的胎面胶在抗湿滑性能和滚动阻力方面可达到较好的平衡。     

顺丁橡胶/丁苯橡胶共混胶的性能

研究了顺丁橡胶(BR)与牌号分别为ESBR 1502 E、ESBR 1586 E、ESBR 1723 E、ESBR 1739 E、SSBR 2557 S、SSBR 2564 S的丁苯橡胶(SBR)并用后的硫化特性、物理机械性能、回弹性能、耐磨性能、抗湿滑性能和生热性能。结果表明,BR与ESBR 1739 E并用后,焦烧时间缩短,硫化速率加快,其他并用胶的焦烧时间均比BR长,且硫化速率慢;BR与不同牌号SBR并用后拉伸强度、扯断伸长率、撕裂强度和回弹率均有所增大,耐磨性能下降,抗湿滑性能提高,滚动阻力增大,生热增加。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.