影响热塑性聚氨酯弹性体力学性能的因素

热塑性聚氨酯弹性体主要由含OH的低聚物多元醇、小分子扩链剂和异氰酸酯等原料聚合而成。本工作讨论了低聚物多元醇的相对分子质量、扩链剂的用量、异氰酸酯指数和后硫化时间对弹性体力学性能的影响，分析了柔性链段的组成、原材料中的水分含量等对弹性体性能的影响。     

不同原料对合成PUR弹性体性能的影响

采用相同官能度、不同分子量的聚醚多元醇和甲苯二异氰酸酯(TD I)及扩链剂反应合成了系列聚氨酯(PUR)弹性体,同时对所合成的PUR弹性体进行了表征。结果表明,聚醚多元醇的相对分子质量对PUR弹性体的性能有较大影响,相对分子质量越大,柔性链段含量就越多,弹性体的拉伸强度、断裂强度和硬度就减小,断裂伸长率则相对提高。同时也进一步证明了软硬链段之间的均匀分布和较强的相互作用更有利于弹性体力学性能的提高。     

聚氨酯橡胶生产现状及发展前景

聚氨酯橡胶（PUR）也称聚氨酯弹性体,是一类在分子链中含有较多的氨基甲酸酯（-NHCOO-）特性基团的弹性聚合物材料,是以平均相对分子质量600～4000的长链多元醇、相对分子质量61～400的扩链剂和多异氰酸酯为原料制得的。由于共聚物分子结构中存在硬、软两种嵌段结构,同时它在化学结构上没有或很少有化学交联,分子链基本上是线性的,     

TPU用新型抗氧化剂

TPU的中文名称为热塑性聚氨酯弹性体,通常是由二苯甲烷二异氰酸酯（MDI）和大分子多元醇、扩链剂共同反应聚合而成的高分子材料。它的分子结构是由MDI和扩链剂反应得到的刚性嵌段以及MDI和大分子多元醇反应得到的柔性链段交替构成的。     

热塑性聚氨酯弹性体透明性影响因素研究

研究了采用不同类型的异氰酸酯、多元醇及扩链剂来合成热塑性聚氨酯弹性体（TPU）,讨论了软段多元醇的种类及分子量、硬段异氰酸酯的种类、扩链剂的种类及结构特点、增塑剂和微量水分等对TPU透明性的影响。结果表明,影响TPU透明性的主要因素是软段多元醇的种类及分子量、硬段异氰酸酯的种类。     

聚氨酯弹性体耐水性影响因素

以两步法工艺合成聚氨酯弹性体,通过改变多元醇、异氰酸酯种类以及扩链剂种类及配比等,考察了原料种类对聚氨酯弹性体力学性能及耐水性能的影响。结果表明,多元醇种类、异氰酸酯种类对聚氨酯弹性体耐水性影响较大,硬段含量与扩链剂种类对试样耐水性影响较弱,提高交联密度对试样耐水性提高有利。     

IPDI基RIM聚氨酯弹性体

以改性异佛尔酮二异氰酸酯(IPDI)为异氰酸酯组分,聚醚多元醇、扩链剂和自制催化剂等为多元醇组分,利用反应注射成型工艺制备了能够快速固化的RIM-PU弹性体,讨论了影响弹性体力学性能和工艺性能的主要因素。结果表明,异氰酸酯组分的官能度为2.05～2.10,聚醚多元醇相对分子质量为4 500,乙二醇作扩链剂,使用自制的延迟胺复合催化剂,异氰酸酯指数为95～100时制品获得良好的力学性能和工艺性能。     

聚己内酯型聚氨酯弹性体的合成与性能研究

采用聚己内酯多元醇CP-20、异氰酸酯和扩链剂等为主要原料,通过预聚物法合成聚氨酯弹性体。研究了预聚物中ω(-NCO%)含量、异氰酸酯种类、扩链剂种类及扩链系数等对聚氨酯弹性体性能的影响。结果表明,CP-20/TDI-100/MOCA体系和CP-20/MDI-100/BDO体系的聚氨酯弹性体具有优良的物理机械性能。     

聚醚型高硬度聚氨酯弹性体的研制

采用聚氧化丙烯多元醇、二醇扩链剂和多异氰酸酯为原料，用一步法工艺制得一系列高硬度聚氨酯弹性体。讨论了多元醇组分平均每个羟基所对应的链段的相对分子质量(MOH)、平均官能度以及异氰酸酯种类对高硬度聚氨酯弹性体性能的影响。结果表明，采用液化MDI或粗MDI与聚氧化丙烯醚配合使用可以制得邵D硬度大于65的聚醚型高硬度聚氨酯弹性体。     

遇水膨胀聚氨酯弹性体的制备与性能研究

以甲苯二异氰酸酯(TDI)、混合型亲水聚醚多元醇、三羟甲基丙烷(TMP)、1,4-丁二醇(BDO)和3,3'-二氯-4,4'-二氨基-二苯基甲烷(MOCA)等为主要原料,采用预聚体法合成了双组份遇水膨胀聚氨酯弹性体。研究了聚醚多元醇配比,异氰酸酯含量,扩链剂种类及配比等对弹性体性能的影响。结果表明:当聚乙二醇/聚丙二醇质量比是80/20,游离异氰酸酯质量分数是4.2Wt%时,弹性体的综合性能好;用TMP/MOCA作混合扩链剂比TMP/BDO作混合扩链剂的弹性体机械性能好。     

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.     

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.