凹凸棒土填充SBR的性能研究

试验研究不同硅烷偶联剂改性凹凸棒土(简称AT)填充SBR硫化胶的物理性能,并以结合橡胶研究补强机理.结果表明,硅烷偶联剂KH-550,KH-560和Si69能明显提高AT/SBR复合材料的物理性能,热重分析显示这些偶联剂提高了AT/SBR混炼胶的结合橡胶含量,增强了AT与SBR分子之间的相互作用;AT经偶联剂Si69改性后可以部分替代炭黑和白炭黑用于填充SBR.     

离子液体改性白炭黑补强丁苯橡胶性能的研究

研究离子液体(IL)AMI和BMI改性白炭黑补强丁苯橡胶(SBR)的性能,并与未改性白炭黑补强SBR进行对比。结果表明:IL可以改善白炭黑的分散性,抑制白炭黑填料网络的形成,增强白炭黑与SBR的相互作用,促进硫化反应,大大缩短t10和t90,提高硫化胶的交联密度和物理性能;与AMI相比,BMI的改性效果更好。     

热解炭黑的研磨和偶联改性及其对丁苯橡胶的补强作用研究

采用研磨和偶联剂乙烯基三乙氧基硅烷（VTEO）对热解炭黑（CBp）进行改性处理,研究研磨改性CBp和VTEO改性CBp补强对丁苯橡胶（SBR）胶料性能的影响。结果表明：随着研磨时间的延长,CBp粒径减小,与橡胶大分子链的相互作用增强,研磨改性CBp补强SBR胶料的门尼粘度和Fmax－FL增大,硫化胶的物理性能提高;VTEO改性使CBp补强SBR胶料的t10延长,加工安全性提高,当采用1份VTEO改性50份CBp时,硫化胶的拉伸强度提高1.6 MPa。     

甲基丙烯酸镁补强EVM的硫化反应动力学

在过氧化物硫化体系作用下，甲基丙烯酸镁（MDMA）对乙烯－乙酸乙烯共聚物（EVM）具有较好的补强作用。通过差示扫描量热（DSC）分析研究MDMA补强EVM混炼胶的硫化反应动力学，并分别采用Ozawa法和Kissinger法计算硫化反应动力学参数。结果表明，MDMA补强的EVM硫化过程遵循一级反应，采用Ozawa法和Kissinger法计算的硫化反应活化能具有较好的一致性，分别为127.0,126.3kJ/mol。     

不同硅烷偶联剂对填充胶料硫化反应的影响

研究了硅烷偶联剂对白炭黑填充胶料的硫化反应的影响,探讨了硅烷偶联剂种类和用量对胶料性能的影响。结果表明,在使用白炭黑的SBR胶料配方中加入硅烷偶联剂,可以促进胶料的硫化反应,缩短硫化时间,提高生产效率。在本文所采用的硅烷偶联剂中,Si69对胶料的硫化反应具有最大的促进作用,并促进胶料和填料之间形成了最强的相互作用。     

环氧化低分子聚丁二烯改性白炭黑在SBR中的应用

研究环氧化低相对分子质量反式聚丁二烯(ELMTPB)改性白炭黑在SBR中的应用效果。结果表明，环氧度为10．6％的ELMTPB改性白炭黑填充SBR硫化胶的综合性能较好；硅烷偶联剂Si69改性白炭黑对SBR硫化胶性能的改善效果明显优于ELMTPB改性白炭黑，且Si69用量为8份时，硫化胶拉伸强度和撕裂强度较高；在ELMTPB／Si69并用比不超过4／4时，所得SBR硫化胶拉伸强度和拉断伸长率优于Si69改性白炭黑填充SBR硫化胶；当Si69用量为4份且并用12份ELMTPB时，所得SBR硫化胶性能最佳，表现在300％定伸应力提高28％，拉伸强度提高38％，且拉伸强度和拉断伸长率超过8份Si69改性白炭黑填充SBR硫化胶。     

高岭土补强NR/SBR/BR的红外光谱研究

通过FT-IR仪,对制备的高岭土/NR/SBR/BR复合材料进行了系统的分析和研究.结果表明:硅烷偶联剂与高岭石表面产生了化学键合;在复合材料的硫化过程中硫磺与橡胶大分子形成了C-Sx-C键;高岭土的加入能够影响C-Sx-C键的形成,其内羟基能与橡胶大分子反应;高岭土在偶联剂的作用下融入橡胶基体中,提升了硫化胶的力学性能;FT-IR可以研究高岭土补强NR/SBR/BR复合材料的机理.     

改性玄武岩纤维对NR/SBR并用体系性能影响的研究

通过硅烷偶联剂如Si-69和KH550对玄武岩纤维进行表面改性,考察改性玄武岩纤维对NR/SBR并用胶各项硫化特性、物理机械性能和动态力学性能的影响。实验结果表明:改性玄武岩纤维使得并用胶正硫化时间有所提高,但焦烧时间缩短。其在胶料中分散性得到有效改善,提高了硫化胶的动态力学性能、物理机械性能,并有效降低压缩生热。用量在10~15份时效果最佳,是一种优良的填充补强材料。     

腰果壳油改性木质素对丁苯橡胶性能的影响

研究腰果壳油（CNSL）改性木质素对丁苯橡胶（SBR）物理性能的影响。结果表明：CNSL可以与木质索粒子结合．实现对木质索的改性;采用CNSL改性木质索可以提高木质索对SBR的补强效果,当木质素与CNSL质量比为85：15时,改性木质素对SBR的补强效果最好。     

补强体系对天然橡胶硫化胶动态性能的影响

研究了炭黑和经硅烷偶联剂改性的白炭黑补强NR对硫化胶性能和产品动态性能的影响。结果表明,采用硅烷偶联剂改性的白炭黑补强天然橡胶具有较好的耐热氧老化性能,较小的损耗因子,较低的压缩疲劳生热和良好的耐热性能;用白炭黑补强的天然橡胶生产的履带板产品在动态性能试验中具有较小的损耗因子和较低的动态生热量。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

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.