首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 718 毫秒
1.
UV固化水性环氧树脂的改性研究   总被引:7,自引:0,他引:7  
用顺丁烯二酸酐对双酚A型环氧树脂(E-51)进行化学改性引入亲水性基团和不饱和基团,成盐后制得UV固化水性环氧树脂体系。确定了最佳的原料配比、反应温度和时间,并利用红外光谱对产物的结构进行了表征。结果表明:该改性E-51环氧树脂可与水以不同的配比形成水溶液或水乳液,体系具有优良的稳定性;该体系可用紫外光固化。  相似文献   

2.
苯并三唑类紫外线吸收剂的现状及发展趋势   总被引:7,自引:1,他引:7  
综述了不同种类的紫外线吸收剂,着重介绍了苯并三唑类紫外线吸收剂。苯并三唑类紫外线吸收剂由于性能优异而广泛应用于各种高分子合成材料和制品中。但由于其相对分子质量较小,在高分子材料加工过程中,容易通过向表面迁移、表面挥发而引起损失,所以其耐光性比较差。在苯并三唑类紫外线吸收剂分子中引入可聚合的基团使它可以和不同的单体聚合成高分子化合物。从共价键到聚合物链的转变使其在介质中更稳定,更不易迁移和挥发。含有可聚合基团的紫外线吸收剂相比普通的紫外线吸收剂显示出了相当优良的耐光稳定性。  相似文献   

3.
由制碱废渣制脱硫吸收剂配比的室内研究   总被引:5,自引:2,他引:5  
探讨了由制碱废渣和电石渣混合制取脱硫吸收剂,不同混合比例对吸收剂的比表面积、脱硫能力的影响,从而确定最佳配比方案。  相似文献   

4.
以磷酸三丁酯(TBP)作萃取剂,正辛醇作稀释剂,络合萃取处理邻异丙氧苯酚(OP)废水中的酚,考察了p H、稀释剂配比、油/水相比和反应温度等对OP废水中挥发酚萃取效率的影响,并对酚进行了反萃取分离回收。实验结果表明:在p H=3、温度为30℃时,用含5%TBP的正辛醇萃取,萃取率达93%;再用10%的氢氧化钠溶液于45℃,按体积比1∶1反萃取,酚回收率达90%,B/C由0.10提高到0.35。  相似文献   

5.
在分离中使用可逆化学络合法是很有希望的革新领域之一。四氯亚铜铝、甲苯溶液是一种引人注目的新型吸收剂,但用于烯烃分离时存在烷基化副反应。本文描述在吸收剂中添加聚丙烯酸酯、聚醚和聚酯三类大环高分子化合物作阻烷基化剂时,络合分离乙烯的研究情况。  相似文献   

6.
通过预氧化和氨水水热法在含有不同壁数的碳纳米管表面成功引入含氮基团,从而获得了氮掺杂碳纳米管(NCNT),并研究了纳米管壁数对不同NCNT氧还原反应活性的影响。研究表明,各NCNT中氮元素的含量和含氮基团的种类相似,但不同含氮基团的比例则相差较大,其中平均壁数为2.5的NCNT样品含有最低的吡啶氮和石墨氮比例,而该样品却展现出最高的电子转移数和最大的氧还原反应极限扩散电流。分析表明,NCNT的氧还原反应活性决定于纳米管壁数,而不是吡啶氮和石墨氮活性基团的比例,即NCNT的内壁为反应电荷的转移提供了有效导电途径,并通过隧穿效应将电子转移到外壁,而外壁的含氮基团活性位点得到电子从而将O2转变为OH-。随着NCNT壁数的增加,NCNT中电子隧穿效应减弱,NCNT的氧还原反应(ORR)活性也随之降低。  相似文献   

7.
罗漫  肖文德 《涂料工业》2022,52(10):85-88
随着环保要求日趋严格,水性无铜镀银玻璃镜镜背涂料替代溶剂型镀银玻璃镜镜背涂料已经成为必然,但水性无铜镀银玻璃镜镜背涂料的研发一直没有取得实质性的进展。通过梳理历年镀银玻璃镜镜背涂料的相关文献,讨论了溶剂型镀银玻璃镜镜背涂料发展历程中树脂和耐腐蚀剂选型的变化,探讨了水性无铜镀银玻璃镜镜背涂料树脂和耐腐蚀剂选择的原理,认为在水性树脂中含有大量亚氨基基团和磺酸盐基团是提高水性无铜镀银玻璃镜镜背涂料性能的有效途径之一,认为单涂层是水性无铜镀银玻璃镜镜背涂料的发展方向。  相似文献   

8.
曾志  林富钦 《化学世界》1993,34(10):465-469
本文介绍了不同活性的卤代芳烃与活泼亚甲基化合物的芳基化反应。具有强吸电子基团的卤代芳烃与活泼亚甲基化合物在温和的条件下发生反应。没有强吸电子基团的卤代苯与活泼亚甲基化合物在没有催化剂存在时不发生反应,而在铜盐催化下反应顺利进行。  相似文献   

9.
《化工中间体》2005,(7):27-29
高纯度高铁酸钾的稳定合成;9,10-蒽醌-2-磺酰-L-氨基酸的合成;木材防腐剂氨溶烷基铜铵的制备和防腐性能研究; 带荧光基团蒽和芘的杯芳烃衍生物合成进展;以β-月桂烯为原料的新单萜衍生物合成及构造解析;酯交换合成碳酸二苯酯反应及催化剂研究进展;等离子喷涂-水热合成羟基磷灰石涂层的体外稳定性;双马来酰亚胺树脂微球的制备。  相似文献   

10.
由多种齐聚物、活性稀释剂、光引发剂和流平剂制备的CMI罩光清漆,光固化迅速,涂膜性能优异。本文介绍了该漆的配方、光固化试验、性能测试结果,讨论了齐聚物配比、光引发剂选用、稀释剂配比和流平剂对涂层性能的影响。  相似文献   

11.
12.
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.  相似文献   

13.
14.
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.  相似文献   

15.
16.
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.  相似文献   

17.
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.  相似文献   

18.
2008~2009年世界塑料工业进展   总被引:4,自引:1,他引:3  
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。  相似文献   

19.
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.  相似文献   

20.
建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号