封闭型多异氰酸酯固化剂合成工艺研究

以甲乙酮肟为封闭剂封闭TDI得到多异氰酸酯固化剂,并通过控制活性氢与-NCO基团的比例、反应时间、反应温度来确定实验最佳条件;通过红外测试来确定固化剂中基团种类从而判断反应后产物种类;通过热失重测试确定固化剂的解封温度。探讨了在不同条件下-NCO的封闭率,进而确定最佳实验条件为n(活泼H):n(—NCO)为1.2,封闭反应温度控制在80℃左右为宜,反应时间为3h。     

丁酮肟封闭多亚甲基多苯基多异氰酸酯的研究

以丁酮肟为封闭剂,制备了封闭型多异氰酸酯树脂;通过实验,讨论了丁酮肟与异氰酸酯基团的摩尔比、反应温度、反应时间对封闭反应的影响;并通过红外光谱研究了封闭产物解封温度。结果表明,最佳反应条件为n(丁酮肟)/n(-NCO)为1.2,反应温度60℃,反应3 h,且封闭物在120℃左右可以解封。     

对羟基苯甲酸甲酯封端异氰酸酯化合物的合成及性能

用N,N’-二甲基甲酰胺(DMF)作溶剂,对羟基苯甲酸甲酯作封闭剂,研究了其封闭甲苯-2,4二异氰酸酯(TDI)中封闭剂与TDI摩尔比、催化剂用量、反应温度与时间对封闭反应的影响。研究发现:当封闭剂与TDI摩尔比为3.0∶1、添加0.5%(基于TDI与封闭剂总质量)催化剂、反应温度80℃、反应3 h时能够获得99.81%的高封闭率。DSC测试显示,封闭产物在80℃以后即开始出现解封闭,但解封的高峰温度在124.7℃,完全解封的温度为130℃;利用红外光谱和核磁共振测试确定了封端产物的结构。     

异氰酸酯封闭及其解封闭反应的研究

考察了反应温度、溶剂、反应时间及不同封闭剂对异氰酸酯封闭反应的影响。同时对封闭型异氰酸酯的解封闭行为进行了研究,并得到了具有较低解封温度的异氰酸酯封闭产物。     

异氰酸酯的封闭反应和解封反应

异氰酸酯是性能活泼的化合物,室温下即可与水及含活泼氢的羟基,胺基等化合物化反应。在某些聚氨酯涂料中,常将聚氨酯中-NCO基封闭起来,使用中在高温下使封闭物解封出-NCO基,与羟基组份反应固化。因此有必要对异氰酸酯的封闭反应和解封反应进行研究。本文用化学分析和红外光谱等方法研究了异氰酸酯的封闭反应和解封反应。使TDI与苯酚在不同温度下反应,用化学方法跟踪-NCO基含量随反应时间的变化,发现在120℃下反应6hr,封闭反应基本完成。将封闭物在120～190℃进行红外测试,发现在130℃开始出现2280cm~(-1)的-NCO基特征红外吸收峰,该峰的强度随温度提高而增强,180℃以上峰强度已变化不大。因此,苯酚封闭异氰酸酯的初始解封温度为130℃,在180℃以上解封反应已趋完全。     

对硝基苯酚封闭多亚甲基多苯基多异氰酸酯的研究

异氰酸酯作为木材胶粘剂的主要组分,需要对反应活性较高的-NCO基团进行封闭,以保证胶粘剂的适用期。采用对硝基苯酚封闭多亚甲基多苯基多异氰酸酯（PAPI）,研究了投料比、加料方式、反应温度和反应时间等对封闭反应的影响,并分别采用二正丁胺法定量测定-NCO含量、FT-IR法跟踪检测-NCO、DSC法测定封闭物的解封温度。结果表明：对硝基苯酚可以用作-NCO的封闭剂;采用滴加PAPI的加料方式,当封闭剂过量10%（相对于PAPI中-NCO的物质的量而言）、反应温度为100℃和封闭反应10h时,封闭物的解封温度为106.1～112.94℃。     

对硝基苯酚封闭多亚甲基多苯基多异氰酸酯的研究

异氰酸酯作为木材胶粘剂的主要组分,需要对反应活性较高的-NCO基团进行封闭,以保证胶粘剂的适用期。采用对硝基苯酚封闭多亚甲基多苯基多异氰酸酯(PAPI),研究了投料比、加料方式、反应温度和反应时间等对封闭反应的影响,并分别采用二正丁胺法定量测定-NCO含量、FT-IR法跟踪检测-NCO、DSC法测定封闭物的解封温度。结果表明:对硝基苯酚可以用作-NCO的封闭剂;采用滴加PAPI的加料方式,当封闭剂过量10%(相对于PAPI中-NCO的物质的量而言)、反应温度为100℃和封闭反应10h时,封闭物的解封温度为106.1～112.94℃。     

甲乙酮肟封闭二苯基甲烷二异氰酸酯的合成

异氰酸酯可作为热硫化型橡胶-金属及其他胶粘剂复合体系的重要组分,需对高活性的异氰酸酯(-NCO)基团进行完全封闭,以保证胶粘剂各组分的相容及稳定性。采用甲乙酮肟封闭二苯基甲烷二异氰酸酯(MDI)预聚体,制备了解封温度130℃的完全封闭型MDI预聚体;研究了投料比、反应温度、反应时间对封闭反应的影响;通过示差扫描量热仪测定了封闭物的解封温度。     

聚醚二元醇与异氰酸酯封端反应的研究

以聚醚二元醇和二苯甲烷二异氰酸酯(MDI)为原料合成预聚体,分别以丙酮肟、甲乙酮肟、丁二酮肟和硝基甲烷作为封闭剂,制备了二苯甲烷二异氰酸酯固化剂。用于阴极电泳涂料,以降低固化温度。利用化学滴定、红外光谱和热重分析(TG)等分析手段对预聚体和异氰酸酯固化剂进行了表征和分析。实验结果表明解封反应时间及解封温度与封闭剂种类有关,甲乙酮肟封闭的异氰酸酯固化剂的解封温度最低,为130℃,解封时间为20 min。     

封端异氰酸酯的制备及其解封研究

用甲乙酮肟(MEKO)对端NCO预聚体进行封端,考查了不同的封端率对端NCO预聚体黏度的影响.用TGA、DSC、TG-IR等对封端聚氨酯解封过程进行研究.实验结果表明,当封端聚氨酯中残余NCO%低于0.1%时,贮存期可达1年以上.H'NMR分析表明,端异氰酸酯封闭成功.MEKO封端的聚氧酯在105℃解封,与聚醚胺混合后...     

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。     

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.     

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.     

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.