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聚苯乙烯在超临界甲苯中的可视降解及动力学 总被引:1,自引:0,他引:1
采用微型可视反应器考察了在超临界甲苯中聚苯乙烯降解的相变过程. 随温度升高聚苯乙烯在甲苯中迅速溶解,体系在略高于甲苯临界点处气液两相界面消失,且伴随着临界乳光现象,随后反应体系呈均相. 考察了聚苯乙烯超临界降解和热降解的反应特性,结果表明,聚苯乙烯超临界降解转化率明显高于热降解转化率;聚苯乙烯超临界降解初期分子量迅速降低的同时转化率也快速上升,而聚苯乙烯热降解初期分子量迅速降低过程中转化率很低. 由于聚苯乙烯在超临界甲苯中降解是均相反应,显著降低了反应体系的密度和粘度,改善了传递效果,因此超临界降解速率明显提高. 聚苯乙烯降解反应为一级反应,在温度为330~370℃时热降解活化能为186.1 kJ/mol,超临界体系改善了降解环境,活化能明显降低,为143.5 kJ/mol. 相似文献
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研究了溶剂法回收聚苯乙烯泡沫塑料(EPS)的操作方法和优化工艺条件.通过单因素实验考察了以甲苯/二氯乙烷为混合溶剂溶解EPS,然后通过沉淀法制备聚苯乙烯(PS)颗粒.结果表明,优化的工艺条件为甲苯/二氯乙烷混合溶剂中甲苯的体积分数为85%,溶解温度为50℃,溶解时间为30 min,以体积分数为95%乙醇为沉淀剂.PS回收率可达94%以上. 相似文献
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在超临界水中聚苯乙烯泡沫的降解 总被引:8,自引:0,他引:8
本文研究了聚苯乙烯泡沫在超临界水中的降解反应。考查了反应时间、温度和添加剂对降解反应的影响。实验结果显示,超临界水能将聚苯乙烯泡沫降解为油状产物。在反应的前30min内,分子量降低了约98%;提高温度对反应时间短的和/或无添加剂的配方有明显的促降解作用;添加剂用量在5%左右时,可得到更大的效率/成本比。 相似文献
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对胜利褐煤在甲醇、碱体系中的超临界反应行为进行了研究,考察了反应温度、反应时间和碱的种类分别对胜利褐煤转化率、产物收率和分布规律的影响.结果表明,反应温度显著影响褐煤的转化率和产物收率,产物主要为四氢呋喃可溶组分(占67%~85%)和甲苯可溶组分(占8%~22%);300℃时,胜利褐煤在甲醇-NaOH体系中转化率和收率最高(99%左右);反应时间显著影响褐煤的转化率和产物收率,80 min后褐煤的转化率和产物收率分别为99%和100%;反应过程中四氢呋喃可溶组分可转化为甲苯可溶组分、正己烷可溶组分和水溶性组分;碱的种类对褐煤超临界醇解转化率和产物收率有显著影响. 相似文献
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超临界介质中三相浆态床甲醇合成 总被引:1,自引:0,他引:1
在总压6.0~7.0 MPa、合成气分压3.0~3.7 MPa、温度235~260 ℃、气体质量空速450~1600 L(STP)8226;(kg cat)-18226;h-1的实验条件下,采用液体石蜡为惰性液相热载体,正己烷作为超临界介质,于机械搅拌反应釜中对催化剂C302-2进行了介质处于超临界状态的三相浆态床甲醇合成过程研究,考察了操作条件对CO转化率和甲醇出口摩尔分数的影响,结果表明在正己烷处于超临界状态的反应温度范围内CO转化率和甲醇出口含量皆随温度的增大而减小,随质量空速的增加而降低.此外,对使用超临界介质和不使用超临界介质的三相浆态床甲醇合成过程进行了对比实验,超临界状态下三相浆态床甲醇合成的CO转化率和甲醇出口含量皆高于三相浆态床甲醇合成,验证了超临界状态下三相浆态床甲醇合成的优越性. 相似文献
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为了阐明超临界流体对甲醇合成反应的促进作用,在固定床反应器中实验考察了超临界正己烷中合成气制甲醇反应。结果表明:忽略催化剂内扩散阻力时,氮气中甲醇合成反应的反应器出口甲醇浓度低于平衡值,而超临界正己烷介质中甲醇合成反应的反应器出口甲醇浓度远高于平衡值。此外,建立了固定床反应器内超临界正己烷中甲醇合成反应的浓度分布模型,模拟考察了甲醇四缔合体的存在对反应结果的影响,发现由于甲醇分子间的氢键缔合大大降低了催化剂表面单体甲醇浓度,促进平衡向着甲醇合成反应方向进行,使得固定床出口甲醇浓度大于平衡值。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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
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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. 相似文献
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Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed. 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
收集了2007年7月~2008年6月世界塑料工业的相关资料,介绍了2007~2008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、不饱和聚酯树脂、环氧树脂)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
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
收集了2005年7月~2006年6月国外塑料工业的相关资料,介绍了2005—2006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生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。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(聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、通用热固性树脂(酚醛、聚氨酯、不饱和树脂、环氧树脂)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。 相似文献