不同预处理酶解木质素对丁腈橡胶的补强性能研究

采用球磨、喷雾干燥、气流粉碎三种方法分别对酶解木质素(EHL)进行预处理,考察其对丁腈橡胶(NBR)的补强性能影响。结果表明,EHL经气流粉碎预处理后的堆积密度最小(0.3329 g·cm-3),其在NBR基质中的分散粒径最细(约为2.5μm)且最均匀,对NBR的补强效果也最好。硫化胶的综合力学性能方面,气流粉碎预处理方法明显优于球磨法和喷雾干燥法。当EHL的用量为40质量份(phr)时,气流粉碎的NBR/EHL硫化胶的拉伸强度比球磨法、喷雾干燥法分别高出24.44%、61.29%;比空白NBR的拉伸强度提高257%。热重及热氧老化力学性能分析表明,酶解木质素在NBR/EHL共混体系中起到一定的热稳定及抗老化作用。扫描电镜图像显示,气流粉碎的酶解木质素与NBR的相容性比球磨、喷雾干燥法的有较大提高,木质素颗粒与橡胶相间的相互作用力较强。     

微观结构对丁腈橡胶硫化胶物理性能的影响

研究橡胶基体及填料微观结构对丁腈橡胶(NBR)硫化胶物理性能的影响。结果表明:随着丙烯腈质量分数的增大,炭黑补强NBR硫化胶的拉伸强度先增大后减小,拉断伸长率减小,邵尔A型硬度和撕裂强度增大;随着生胶门尼粘度的增大,炭黑补强NBR硫化胶的邵尔A型硬度基本不变,定伸应力增大,拉伸强度和拉断伸长率减小;随着炭黑粒径的减小,硫化胶的定伸应力呈增大趋势,拉伸强度和撕裂强度增大,高定伸下炭黑粒径对应力的贡献较大;随着炭黑结构度的提高,硫化胶定伸应力增大,拉伸强度和撕裂强度减小。     

硫化剂DCP对NBR/木质素硫化胶性能的影响

研究了用DCP作硫化剂时木质素的用量对NBR胶料硫化特性和硫化胶物理性能的影响,并与硫黄硫化体系进行了对比。试验结果表明,随着木质素用量的增大,NBR胶料的ML和MH增大,t10保持不变,t90有所延长;当木质素用量为50份时,NBR硫化胶的综合物理性能最佳,拉伸强度、定伸应力和撕裂强度均明显高于硫黄硫化胶。动态粘弹特性分析表明,木质素与NBR具有良好的相容性,DCP硫化胶的玻璃化转变温度比硫黄硫为胶约低4℃。综合性能分析认为,硫化剂DCP对NBR／木质素体系具有原位反应相容作用。     

小麦秸秆粉末在NBR中的应用初探

试验研究小麦秸秆粉末在NBR中的应用效果.结果表明,随着小麦秸秆粉末用量的增大,NBR胶料的硫化速度提高,焦烧时间缩短;小麦秸秆粉末粒径为245 μm、用量为15份时,NBR硫化胶的综合物理性能较好;经硅烷偶联剂KH-550溶液处理的小麦秸杆粉末对NBR的补强效果较好.     

六次甲基四胺对NRB／木质素性能的影响

研究了六欠甲基四胺（（CH2）6N4）对NBR/木质素混炼胶高温变性及对硫化胶性能的影响。结果表明：（CH2)6N4用量为10份时,硫化胶拉伸强度和撕裂强度比未加时分别提高近1.5倍和1倍;（CH2）6N4用量从0份增大到15份,硫化胶表现交联密度提高约30%;高温混炼时共混体系的粘度随时间而延长上升,而且温度越高上升的幅度越大;DMA分析表明,NBR/木质素硫化胶只有一个Tg,（CH2）6H4用量由5份提高到20份,硫化胶的Tg升高近2℃。     

废轮胎裂解炭黑在丁腈橡胶中的应用

研究了废轮胎裂解炭黑(PCB)的化学组成,同时将PCB用于丁腈橡胶(NBR)中,与其他填料对比,研究PCB对NBR加工工艺性能和硫化胶物理性能的影响,并和其他填料进行了对比。结果表明:PCB的化学组成主要是C、O、S、Zn、Si等,灰分含量比较高,达13.3%。PCB对NBR胶混炼胶加工工艺性能的影响不大。与N330、N774和CaCO3对比发现,PCB对NBR硫化胶具有一定的补强作用,效果明显优于CaCO3。随着PCB用量的增加,硫化胶的拉伸强度、撕裂强度、定伸应力显著提高。当PCB用量为50份,NBR硫化胶的拉伸强度达到15MPa,撕裂强度可提高2倍。     

酚醛树脂对NBR性能的影响

试验研究两种酚醛树脂(腰果壳油改性,且含有六亚甲基四胺的粉末状热固性酚醛树脂SP6600和未经改性酚醛树脂SFP118)对NBR硫化胶性能的影响.结果表明,树脂SP6600能够增大NBR硫化胶的100%定伸应力和撕裂强度,并使其具有较好的耐热老化和耐磨性能,降低动态生热性能;树脂SFP118使NBR硫化胶的拉伸强度稍有减小,其它性能均不及SP6600补强的NBR硫化胶.     

三乙烯四胺丙烯酸盐增强丁腈橡胶的研究

对三乙烯四胺丙烯酸盐（AnAA）补强丁腈橡胶（NBR）的性能进行了研究。结果表明，AnAA对NBR硫化胶具有较好的补强效果，当AnAA含量为10份时，硫化胶具有最佳综合力学性能。在AnAA补强NBR的硫化胶交联网络中存在较高的离子交联结构，并从离子交联密度方面探讨了AnAA对NBR的补强机理。从断裂面的SEM照片分析可知，AnAA在NBR中较易分散形成纳米颗粒。这些纳米颗粒对NBR起到了较好的补强作用。     

丁腈橡胶/黑液-蒙脱土复合材料压缩永久变形的研究

以造纸黑液和蒙脱土为原料制备黑液-蒙脱土复合物(BL-MMT),并将其作为填料,通过机械混炼制备了丁腈橡胶/黑液-蒙脱土(NBR/BL-MMT)复合材料。考察了BL-MMT用量、硫化体系、填充体系对NBR/BL-MMT复合材料压缩永久变形的影响。实验结果表明:当BL-MMT的用量为50 phr时,使用过氧化物硫化体系的硫化胶压缩永久变形优于硫磺硫化体系,且随着过氧化物含量的增加,硫化胶的压缩永久变形减小。当过氧化物为1.5 phr时,综合性能较好。无机填料填充NBR/BL-MMT(100/50)复合物,将导致硫化胶的压缩永久变形增大。在添加相同量的无机填料时,填充白炭黑的硫化胶压缩永久变形最大,其次为轻质碳酸钙、重质碳酸钙。     

补强体系对NBR油封性能的影响

研究补强体系对NBR油封胶料性能的影响,通过台架试验评价油封的使用性能.结果表明,采用高耐磨炭黑/半补强炭黑或快压出炭黑补强的NBR硫化胶物理性能优异,但不适宜生产中高速油封;采用白炭黑/轻质氧化镁补强的NBR硫化胶物理性能略差,但可满足油封的要求,且耐热老化和耐油性能良好,所制备油封使用性能优异.     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.