低分子量聚丙烯酸钠的合成与分析

低分子量的聚丙烯酸钠具有良好的分散性能,本文以丙烯酸为单体,过硫酸铵为引发剂,异丙醇为链转移剂,通过中和法合成了低分子量的聚丙烯酸钠,用端基法测得其数均分子量。通过改变单体浓度、引发剂用量、链转移剂用量和反应温度等反应条件,得出了各合成因素对聚丙烯酸钠分子量影响的趋势。     

复合引发体系制备聚丙烯酸钠

采用水溶液聚合,使用了由氧化还原引发体系和偶氮类引发剂组成的一种复合引发体系制备高分子量聚丙烯酸钠。考察了引发剂用量、反应温度、单体中和度、单体浓度对分子量的影响,并对复合引发体系与氧化还原引发体系进行了对比,得出优化条件:各引发剂用量:M用量=0.48‰,K2S2O8用量=0.2‰,NaHSO3用量=0.2‰,脲素用量=5‰,乙二胺用量=5‰;聚合工艺条件为:聚合温度25℃,单体中和度80%,单体浓度25%,聚丙烯酸钠分子量达到1470万。     

静态反相悬浮聚合法合成聚丙烯酸钠

以过氧化氢为引发剂,以食用植物油如菜子油、花生油、茶油、葵花油、大豆油或者玉米油为分散相,采用静态反相悬浮聚合工艺合成聚丙烯酸钠,研究了引发剂用量、分散相以及反应温度对聚丙烯酸钠分子量的影响。结果表明,随过氧化氢浓度增大、丙烯酸钠单体浓度降低、聚丙烯酸钠的分子量降低;玉米油为分散相时聚丙烯酸钠的分子量最大;随反应温度升高,聚丙烯酸钠的分子量增大;但反应温度超过60℃时,聚丙烯酸钠的分子量随反应温度升高而降低。     

制备聚丙烯酸钠分散剂的最佳工艺条件探究

以丙烯酸为单体,采用过硫酸铵和亚硫酸氢钠为氧化还原引发剂,同时亚硫酸氢钠又作为链转移剂来制备低分子量的聚丙烯酸钠.研究了单体浓度、引发剂用量、链转移剂用量以及反应温度对分子量和分散性的影响.通过正交设计实验确定了最佳反应条件:过硫酸铵用量为5.56%,亚硫酸氢钠为4.44%,单体浓度为33.3%,温度70℃,反应时间为3h.     

制备聚丙烯酸钠分散剂的最佳工艺条件探究

以丙烯酸为单体,采用过硫酸铵和亚硫酸氢钠为氧化还原引发剂,同时亚硫酸氢钠又作为链转移剂来制备低分子量的聚丙烯酸钠.研究了单体浓度、引发剂用量、链转移剂用量以及反应温度对分子量和分散性的影响.通过正交设计实验确定了最佳反应条件过硫酸铵用量为5.56%,亚硫酸氢钠为4.44%,单体浓度为33.3%,温度70℃,反应时间为3h.     

制备聚丙烯酸钠分散剂的最佳工艺条件探究

以丙烯酸为单体,采用过硫酸铵和亚硫酸氢钠为氧化还原引发剂,同时亚硫酸氢钠又作为链转移剂来制备低分子量的聚丙烯酸钠。研究了单体浓度、引发剂用量、链转移剂用量以及反应温度对分子量和分散性的影响。通过正交设计实验确定了最佳反应条件:过硫酸铵用量为 5 56%,亚硫酸氢钠为 4 44%,单体浓度为 33 3%,温度 70℃,反应时间为 3h。     

一种油田防垢剂的合成及评价实验研究

以过硫酸铵-亚硫酸氢钠为氧化还原引发体系、亚硫酸氢钠同时作链转移剂合成低相对分子量的聚丙烯酸钠,作为一种油田防垢剂。研究了单体、引发剂及链转移剂的用量、反应温度和时间等对产物相对分子质量的影响,并对不同相对分子量的产物进行了防垢性能的评价。结果表明反应温度为60℃、单体质量分数30%、引发剂用量0.6%、链转移剂用量5%、反应时间2 h时,可制得聚丙烯酸钠的粘均相对分子质量在2 000~3 000,作为油田防垢剂防垢效率高、效果好。     

低分子量聚丙烯酸钠的合成

采用自由基溶液聚合方法制备了低分子量聚丙烯酸钠,研究了链转移剂用量、单体浓度、温度、反应时间及引发剂用量、加料方式等因素对聚丙烯酸钠分子量的影响。实验结果表明,合成了低分子量(500-10000)聚丙烯酸钠。     

低分子量聚丙烯酸钠的合成及应用

采用溶液聚合方法合成低分子量聚丙烯酸钠,得出制取低分子量聚丙烯酸钠的最佳适宜条件为：单体用量25 g、引发剂用量为单体用量的7%、链转移剂用量7.5 g、聚合温度为80℃。     

聚丙烯酸铵水溶液聚合研究

采用水溶液聚合法合成聚丙烯酸铵,考察了温度、EDTA、引发剂、NaCl、聚合时间、链转移剂以及单体浓度对聚丙烯酸铵相对分子量的影响。结果表明,最佳聚合条件为:反应温度30℃,EDTA用量0.03%,引发剂用量0.03%,NaCl用量0.6%,反应时间3 h,单体浓度50%,链转移剂用量0.7%。在此条件下,合成的聚丙烯酸铵相对分子量为1 905万,且具有良好的溶解性能。     

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.     

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.     

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.     

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。