环氧树脂中温固化促进剂的研制

双氰胺固化环氧树脂时的固化温度高,利用不同含量的乳酸改性咪唑生成的盐作为环氧树脂／双氰胺体系固化促进剂对该体系进行了改进。结果表明,改性咪唑促进剂可以使环氧树脂／双氰胺体系的固化温度降低,并且贮存期显著增加,耐水性和耐热老化性能增加。     

潜伏性环氧树脂固化促进剂M-Cd的合成及其应用

采用间苯二胺和溴化镉合成了一种具有潜伏性的环氧树脂固化促进剂M－Cd它是一种络合物，将它应用于二氰二胺／环氧树脂脂固化体系的高温结构粘剂中，能够显著地降低粘剂的固化温度，缩短固化时间，本文还讨论了合成该促进剂主要成分的投料比，应用于二氰二胺／环氧树脂固化体系的高温结构胶粘剂中该促进剂的使用量以及固化条件对粘剂力学性能的影响，同时还考核了应用该促进剂M的高温结构胶粘剂的综合性能。     

含有环氧基的丙烯酸酯的合成及其固化物的研究

采用脂肪族环氧树脂(EP-664)与丙烯酸(AA)合成了低黏度的含有环氧基的丙烯酸酯(AEG),该反应性酯类化合物与双酚A型环氧树脂(E-44、EP-6002)共混,以甲基六氢苯酐(MeHHPA)为固化剂,并分别采用三级胺和2-乙基-4-甲基咪唑(2E4MZ)为促进剂,通过混合物黏度曲线的变化与其固化物力学性能的测试,研究了AEG含量对环氧树脂体系黏度的变化和固化物力学性能的影响。结果显示,AEG的添加可以有效地降低树脂体系的黏度,25℃下混合体系黏度仅为300～600mPa·s;其固化物的力学性能随AEG含量的增加先增加后降低,具有最大值。三级胺固化体系的力学性能明显优于2E4MZ固化体系,当w(AEG)为20%时,固化物的综合力学性能最好。     

有机酸改性咪唑环氧树脂固化促进剂的研究

二氰二胺作为环氧树脂的潜伏性固化剂,其固化物机械性能和介电性能优异。但由于二氰二胺与环氧树脂相溶性差,得不到均匀的组成物,且环氧树脂/二氰二胺体系的固化过程需在高于160℃的温度中进行。利用不同含量的有机酸与咪唑3位氮原子中和,改性生成的盐作为环氧树脂/二氰二胺体系固化促进剂,对该体系进行了改进,使其能够在中温(90～120℃)条件下固化。利用IR对改性产物进行了表征,并对未加促进剂的环氧树脂/双氰胺体系和以咪唑及有机酸改性咪唑为促进剂三种体系分别进行了差热分析。结果表明,有机酸改性咪唑促进剂可以使环氧树脂/二氰二胺体系的固化温度降低近50℃,并且适用期显著增加,长达141d,耐水性和耐热老化性能增加。     

环氧树脂/多元硫醇体系的低温快速固化

通过凝胶时间测定,红外和凝胶渗透色谱分析研究了分别以三乙胺、苄基二甲胺、2,4,6-三[(二甲氨基)甲基]苯酚及1,8-二氮杂环[5,4,0]-十一烯,即二环脒为促进剂的环氧树脂(E-51)/多元硫醇(T-35)体系的固化特性。结果表明,E-51/T-35体系的固化速度明显高于传统的以脂肪族多胺类为固化剂的环氧树脂体系,且该体系的凝胶时间随着体系中环氧基/巯基配比的增加而缩短,随促进剂碱性的增强及含量的增加缩短,随着反应温度的降低延长。     

处理温度对酶解木质素改性环氧树脂性能的影响

将玉米秸秆酶解木质素与双酚A环氧树脂混合,在不同温度下预处理一定时间,用以改性环氧树脂。通过改性后树脂黏度、固化反应过程、固化后树脂的玻璃化转变温度、凝胶含量以及老化不同时间后树脂力学性能的测试,研究了处理温度对酶解木质素改性环氧树脂性能的影响。结果表明,改性后环氧树脂的黏度随处理温度的提高而增加,改性树脂/聚酰胺混合体系的固化峰值温度随处理温度的提高而降低;玻璃化转变温度和凝胶含量随处理温度的提高而增大;高温预处理的改性树脂固化物的弯曲强度均有不同程度的提高,老化后,材料的弯曲强度先升高,后降低,冲击强度则随老化时间的延长呈现持续降低的趋势。     

正丁基缩水甘油醚改性环氧树脂的性能及固化动力学

通过粘度、力学性能测试,示差扫描量热分析和热重分析研究了正丁基缩水甘油醚(501)对环氧树脂性能的影响,并研究了501/环氧树脂体系的固化反应动力学。结果表明,随着501用量的增加,体系的粘度显著降低,拉伸强度和耐热性有所下降,而弯曲强度先增加后降低,但仍有所提高。体系的恒温固化温度随501用量的增加逐渐降低,活化能也呈降低趋势,而反应级数均在0.93左右波动,501的添加对环氧树脂体系的固化反应机理没有明显影响。     

含氟形状记忆环氧树脂体系的制备与性能

将氢化环氧树脂(AL-3040)和自制的含氟环氧树脂按不同的物质的量比共混,以聚丙二醇二缩水甘油醚(XY-207)为环氧稀释剂、1,8-薄荷烷二胺(MDA)为固化剂,完全固化之后制备出一种新型的含氟形状记忆环氧树脂体系,并表征了其分子结构、含氟环氧树脂含量对固化体系储能模量和形状记忆性能的影响,测试了体系表面和冲击断面含氟量以及冲击力学性能。研究结果表明:增大体系含氟环氧树脂含量时,固化体系的交联度增大;固化体系的储能模量随含氟环氧树脂含量的增加而增大;该形状记忆含氟环氧树脂体系具有良好的形状记忆性能,形变完全的时间随体系含氟环氧树脂含量的增加而缩短。     

酸酐固化环氧树脂潜伏性促进体系的研究

本文应用DSC、TBA和旋转粘度计等手段对一种乙酰丙酮过渡金属络合物对酸酐固化环氧树脂体系的潜伏性促进作用和固化反应动力学进行了研究。结果表明,这种乙酰丙酮金属络合物可做为酸酐固化环氧树脂体系的潜伏性促进剂.其体系的固化反应速率随金属络合物浓度的增加而加快.在160℃～180℃体系具有非常短的凝胶化时间。在室温下,其体系的贮存使用期可达二个月以上。整个固化反应过程遵循一级动力学.对含有此促进剂和叔胺促进剂的酸酐固化环氧树脂体系固化产物进行了电、力学和耐热性能的研究和对比。     

E-44环氧树脂固化物的力学性能影响因素研究

基于环氧树脂/聚酰胺体系的固化反应机理,通过实验研究了E-44环氧树脂固化物的力学性能随650聚酰胺树脂的添加量、固化条件的变化规律。弯曲强度和拉伸剪切强度试验结果表明:在同一固化条件下,随着"650"聚酰胺含量的增加,固化物的力学性能随之增加;在温度60℃时固化物的力学性能优于温度25℃时固化物的力学性能。     

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.     

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。     

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.     

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.     

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.