EPDM硫化橡胶的热稳定性研究

对ＥＰＤＭ的过氧化物硫化、硫黄硫化和含硫化合物硫化以及两种不同硫化体系并用的硫化胶热稳定性进行比较，优选热稳定性较好的硫化体系用于产品的制造。采用过氧化二异丙苯（ＤＣＰ）硫化的硫化胶虽具有极好的热稳定性，但其耐撕裂性能较差，且价格较高。因此可考虑采用ＤＣＰ的并用硫化体系。当ＤＣＰ用量为５份，硫黄用量不超过１份时，硫化胶具有较好的热稳定性。     

耐汽车合成制动液的EPDM胶料配方与工艺研究

在配方设计上，通过选择合适的其它橡胶与ＥＰＤＭ并用，很好地解决了制品尺寸缩小问题，选择过氧化物硫化体系，对ＥＰＤＭ胶料的强度、耐热性、耐压缩永久变形等性能，都取得了较为满意的效果。在工艺上，增加制品后处理工序，有效地改进了ＥＰＤＭ硫化胶的压缩永久变形性能，降低了老化前、后硬度的变化量。     

EPDM/CR共混物的研究

研究了橡胶共混比、硫化体系、高耐磨炭黑用量及共混工艺等对ＥＰＤＭ／ＣＲ共混物性能的影响,考察了共混物的力学性能、耐高温硝酸性能、热空气老化性能、耐辐射性能和相容性。试验结果表明,采用炭黑全部加入ＥＰＤＭ中然后与ＣＲ混合的共混工艺,所得硫化胶的力学性能超过两种橡胶硫化胶力学性能的加和值;共混胶中ＥＰＤＭ采用硫黄硫化才能得到比较好的力学性能。硫化动力学研究表明ＣＲ的硫化速度较ＥＰＤＭ的硫化速度对温度的依赖性小。ＤＳＣ和ＤＶＡ分析结果表明共混胶具有两个明显的玻璃化转变温度,为热力学不相容体系。研制的ＥＰＤＭ／ＣＲ共混物具有耐老化、耐高温硝酸、耐辐射、粘合好等优良性能。     

丁腈橡胶/聚甲醛共混物动态硫化的研究

采用２４０２树脂硫化体系以动态硫化方法制备了了腈橡胶（ＮＢＲ）／聚甲醛（ＰＯＭ）热塑性弹性体。研究了丙烯睛含量、硫化体系、橡塑比等对共混物性能的影响。实验结果表明：ＮＢＲ中丙烯睛含量增加，共混物的拉伸强度显著提高；随着ＰＯＭ用量增加，共混物的强度略有提高，表观粘度降低，加工性能改善，电性能、老化性能和耐油性能均得到明显提高。ＤＳＣ分析表明，共混物中ＰＯＭ的结晶度明显比纯ＰＯＭ低，熔点也有所下降。     

乙炔炭黑填充VMQ/EPDM共混导电橡胶的流变性能和结构分析

用孟山都流交仪测定了不同共混比的甲基乙烯基硅橡胶（ＶＭＱ）／ＥＰＤＭ共混混炼胶的流变性能；用网笼法测定了炭黑在共混体系两相中的比例；研究了薄通次数对共混硫化胶体积电阻率的影响；用透射电镜观察了硫化胶的形态。根据试验结果得出：适当并用比和炭黑填充量的ＶＭＱ／ＥＰＤＭ共混硫化胶具有高导电性的原因是：两相粘度相差较大，共混体系为明显的“海－岛”结构，而且炭黑在共混体系两相中的浓度不同；具有高导电性及其加工稳定性的ＶＭＱ／ＥＰＤＭ共混导电橡胶的最佳并用比例为８０／２０—７０／３０。     

HNBR/EPDM共混物结构与性能研究

分别采用过氧化物和硫给予体作交联剂,考察了不同共混比对氢化丁腈橡胶（ＨＮＢＲ）／ＥＰＤＭ共混物性能的影响,并能力ＤＳＣ和ＴＥＭ分析了共混物的相容性,对两胶的共硫化也作了初步探讨。结果表明,两种硫化体系硫化的共混胶扯断伸长率保持率均在６０％以上,都具有优异的耐热氧老化性能。随ＨＮＢＲ用量增大,共混物的定伸应力、拉伸强度和撕裂强度均提高,磨耗明显降低。ＨＮＢＲ和ＥＰＤＭ为不相容体系,但硫化仪曲线显示二     

预处理短纤维对VMQ/EPDM共混导电橡胶某些性能的影响

研究了预处理短纤维用量对乙炔炭黑填充甲基乙烯基硅橡胶（ＶＭＱ）／ＥＰＤＭ共混硫化胶拉伸、撕裂、耐屈挠疲劳和导电性能的影响。实验结果表明，加入适量短纤维对ＶＭＱ／ＥＰＤＭ体系有一定的补强作用；纤维用量较大时，导电性能下降。加入４．０份左右的预处理短纤维，可使ＶＭＱ／ＥＰＤＭ共混导电橡胶获得良好的物理机械性能和导电性能     

动态硫化PP／HDPE／EPDM三元共混物的流变性能

本文采用不同的硫化剂，不同的硫化时间，对动态硫化的ＰＰ／ＨＤＰＥ／ＥＰＤＭ三元共混物的流变性能进行了研究。结果表明：１共混体系为假塑体，表现出切力变稀现象；２在低剪切应力下，以Ｍ为硫化剂的粘度与纯机械共混体系的粘度有很大差值，此差值随剪切应力的提高迅速减少；３以ＤＣＰ为硫化剂，体系的粘度低于纯机械共混体系的粘度。     

不同硫化体系动态硫化EPDM/PP热塑性弹性体流变性能的研究

研究了不同硫化体系、硫化剂用量及共混比对ＥＰＤＭ／ＰＰ共混物流变性能的影响。结果表明,选择酚醛树脂硫化体系、控制酚醛树脂用量为５ 份以及ＥＰＤＭ／ＰＰ共混比为５０／５０,可以得到挤出表面最为光滑的共混物。     

1,2-PBR和BR对EPDM硫化和力学性能的影响

考察了过氧化物硫化体系和硫黄硫化体系ＥＰＤＭ／１,２－聚丁二烯橡胶（１,２－ＰＢＲ）和ＥＰＤＭ／ＢＲ并用胶的硫化特性、交联密度和物理性质。结果表明：采用过氧化物硫化体系时,ＥＰＤＭ与１,２－ＰＢＲ和ＢＲ并用后,硫化胶的交联密度、１００％定伸应力、邵尔Ａ型硬度和撕裂强度增大,且前的增幅较大;采用硫黄硫化体系时,１,２－ＰＢＲ和ＢＲ均可提高ＥＰＤＭ的硫化速率,且随着１,２－ＰＢＲ用量的增大,硫化胶的     

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.     

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.