EVM橡胶过氧化物交联体系的研究

研究了交联剂过氧化二异丙苯(DCP)、双叔丁基过氧异丙基苯(BIPB)、2,5-二甲基-双(叔丁基过氧基)己烷(DBPMH)以及助交联剂三烯丙基异氰脲酸酯(TAIC)、三烯丙基氰脲酸酯(TAC)、N,N′-间苯撑双马来酰亚胺(HVA-2)对乙烯-醋酸乙烯酯橡胶(EVM)硫化特性、交联密度以及力学性能的影响。通过测试硫化曲线、力学性能和交联密度还研究了无机阻燃填料氢氧化镁的隔离效应对EVM橡胶交联效率的影响。结果表明,EVM橡胶最优过氧化物交联体系为BIPB和TAIC,其最佳配比为2.3/2.5,此时EVM橡胶有较好交联效率、交联速率和力学性能。氢氧化镁对EVM橡胶的交联效率没有影响,但硅烷化氢氧化镁能够提高EVM橡胶的表观交联密度。使用高交联效率过氧化物交联体系BIPB和TAIC,并添加硅烷化氢氧化镁,可平衡EVM橡胶阻燃性能和力学性能。     

第三单体含量和助交联剂用量对三元乙丙橡胶耐磷酸酯液压油性能的影响

研究三元乙丙橡胶(EPDM)第三单体(亚乙基降冰片烯)含量和助交联剂三羟甲基丙烷三甲基丙烯酸酯(TMPTMA)用量对EPDM胶料耐磷酸酯液压油性能的影响。结果表明:在EPDM第三单体含量相同时,在试验范围内,随着助交联剂TMPTMA用量的增大,胶料的硫化速率加快,交联密度增大,耐磷酸酯液压油性能提高;在助交联剂TMPTMA用量相同时,随着EPDM第三单体含量的增大,胶料的硫化速率加快,交联密度增大,耐磷酸酯液压油性能提高;对于第三单体含量较小的EPDM,当助交联剂TMPTMA用量超过一定值后,其用量增大,胶料的交联密度增幅较小,但耐磷酸酯液压油性能持续提高。     

过氧化物对246型氟橡胶压缩永久变形的影响

研究过氧化物品种、硫化剂DCP和助交联剂TAIC用量以及硫化剂种类对氟橡胶性能的影响.结果表明:在过氧化物BIPB,DBPMH,DCP,DCBP和BPO中,DCP硫化的氟橡胶综合物理性能较好,压缩永久变形较小;随着硫化剂DCP用量的增大,氟橡胶的压缩永久变形呈减小趋势,硫化剂DCP用量为3份时,氟橡胶的物理性能较好,压缩永久变形较小;随着助交联剂TAIC用量的增大,氟橡胶的压缩永久变形呈减小趋势,助交联剂TAIC用量为5份时,氟橡胶的压缩永久变形较小;硫化剂DCP硫化的氟橡胶耐压缩永久变形性能优于3#硫化剂,但不如双酚AF/BPP.     

助交联剂在彩色高硬度EPDM胶料中的应用

研究助交联剂TMPTMA和TAIC用量对高硬度乙丙橡胶(EPDM)混炼胶加工性能和硫化胶力学性能的影响。结果表明,助交联剂TMPTMA不仅有提高硫化速率的作用,也具有一定的软化效果,使混炼胶的流动性提高;随着TMPTMA用量的增加,EPDM硫化胶的硬度、拉伸强度、撕裂强度、100%定伸应力增大,而拉断伸长率和回弹性减小,共混胶的磨耗体积先减小后增大。助交联剂TAIC比TMPTMA的交联反应速度慢,交联密度较高;硬度和定伸应力较高,拉伸强度、撕裂强度、拉断伸长率和耐磨性都有所下降。     

助交联剂对三元乙丙橡胶过氧化物硫化的影响

分别采用三烯丙基异氰脲酸酯(TAIC)、三羟甲基丙烷三甲基丙烯酸酯(TMPTMA)以及高乙烯基聚丁二烯(HVPBd)作为过氧化物硫化三元乙丙橡胶(EPDM)的助交联剂,研究其对EPDM胶料硫化特性及硫化胶力学性能的影响。结果表明,3种助交联剂的添加能明显促进硫化程度,硫化胶的硬度和定伸应力均明显提高,添加TAIC的EPDM混炼胶硫化程度最高,但添加TMPTMA使胶料的焦烧安全性变差,而添加HVPBd的EPDM胶料降解程度最低。通过一级动力学模型及自催化反应模型研究EPDM硫化动力学行为时发现,助交联剂类型影响胶料的硫化反应速率,其中TMPTMA能明显促进硫化反应速率,TAIC次之,而HVPBd几乎没有影响,但硫化反应表观活化能由于助交联剂的添加均出现降低,其中添加TAIC胶料的表观活化能最低。     

交联助剂TAIC对F246氟橡胶性能的影响

研究了交联助剂三烯丙基异氰尿酸酯(TAIC)对F246氟橡胶硫化胶硫化特性、力学性能、耐溶剂性能以及耐热老化性能的影响。研究结果表明,F246氟橡胶在采用过氧化物做交联剂时,TAIC能有效辅助交联反应。随着TAIC用量的增大,混炼胶正硫化时间减少,焦烧时间延长,最大转矩增加;硫化胶交联密度增大;硫化胶硬度增大,拉伸强度变化不大,而撕裂强度和拉断伸长率均下降;当TAIC超过5份后,硫化胶的交联密度变化不大。当交联助剂TAIC用量为5份时,F246氟橡胶硫化胶可获得较好的综合性能。     

助交联剂对硫化剂BIBP硫化氯化聚乙烯电缆护套性能的影响

研究助交联剂TAIC和HVA-2对硫化剂BIBP硫化氯化聚乙烯(CPE)电缆护套性能的影响。结果表明:加入助交联剂的CPE胶料t10和t90缩短,硫化胶的表观交联密度和剪切储能模量增大;与助交联剂TAIC相比,助交联剂HVA-2会降低胶料的焦烧安全性,提高硫化胶的物理性能和耐热老化性能;采用硫化剂BIBP和助交联剂HVA-2硫化的CPE电缆护套性能达到国家标准要求。     

助交联剂对过氧化物硫化氯磺化聚乙烯 胶管胶料性能的影响

研究助交联剂HVA-2用量对过氧化物硫化氯磺化聚乙烯胶管胶料性能的影响。结果表明:随着助交联剂HVA-2用量增大,混炼胶的F_(max)增大,t_(10)变化不大,t_(90)缩短,交联密度增大;硫化胶的硬度和拉伸强度增大,拉断伸长率减小,压缩永久变形减小;老化后,硫化胶的硬度和拉伸强度增大,拉断伸长率减小,且变化幅度随着HVA-2用量增大而减小;油浸泡后,硫化胶的体积减小,且体积变化率随着助交联剂HVA-2用量增大而减小;当助交联剂HVA-2用量为2份时,硫化胶的综合性能较好。     

噻二唑硫化体系对氯化聚乙烯橡胶性能的影响

研究噻二唑硫化体系(硫化剂PT75/促进剂903体系)对氯化聚乙烯橡胶(CM)性能的影响。结果表明:与过氧化物硫化体系(过氧化物BIPB/助交联剂TAIC体系)胶料相比,噻二唑硫化体系胶料的拉伸性能和抗撕裂性能大大改善,耐热老化性能相当,耐油性能较好;硫化剂PT75和促进剂903用量比为2/2时,胶料的压缩永久变形较小,拉伸性能和抗撕裂性能较好,耐热老化性能优异。     

助交联剂TAC对橡胶型氯化聚乙烯性能的影响

探讨了CM在TAC作为助交联剂的情况下用过氧化物硫化的硫化特性、力学性能及交联密度。结果表明,用过氧化物硫化CM时,随助交联剂TAC用量增加,硫化胶的最大扭矩增加,正硫化时间缩短;拉伸强度逐渐增加,永久变形减少。并且从交联密度看,随TAC用量增加,硫化胶的交联密度逐渐增大,有利于提高材料的综合性能。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

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.     

2007～2008年世界塑料工业进展

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.     

2005～2006年国外塑料工业进展

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。