碳/芳基乙炔聚合物复合材料的烧蚀性能

芳基乙炔聚合物(PAA)具有很好的耐热性能，其玻璃化转变温度为327．6℃，起始热分解温度为503℃，最大热分解温度为663℃，900℃时的残碳率高达84％；且用芳基乙炔做基体材料，用碳布做增强材料的碳／芳基乙炔聚合物复合材料的平均线烧蚀速率为0．007mm／s，低于相应的碳／酚醛复合材料的烧蚀速率，可作为新型耐烧蚀材料使用。     

4-炔丙氧基苯基马来酰亚胺共混改性聚芳基乙炔

将4-炔丙氧基苯基马来酰亚胺(简称4-PPM)与聚芳基乙炔(简称PAA)进行共混改性,在保持PAA树脂耐热性的基础上改善其固化工艺性能。用红外、流变及DSC等测试方法研究了共混树脂的固化工艺性能,用TGA及DMA的测试方法研究了共混树脂固化物的耐热性能。结果表明共混树脂具有良好的加工性能,并且固化物也具有良好的耐热性能。玻璃化转变温度高于370℃,在N2中的分解温度高于400℃,失重5%的温度高于413℃,900℃的残留率高于56%。对比各个配比的共混树脂,4-PPM质量分数为50%的树脂表现出较好的固化工艺性能和耐热性能,可作为耐高温复合材料的基体。     

芳基乙炔树脂的固化反应动力学及流变行为研究

通过对芳基乙炔树脂的固化动力学研究确定其适宜的固化工艺。采用DSC和流变分析得到芳基乙炔树脂的特征固化参数及其固化度与温度的关系曲线。结果表明,树脂的起始反应温度为127.1℃,反应峰值温度164.2℃,终止反应温度195.1℃。固化动力学参数为:表观活化能E=190.12kJ/mol,反应级数n=1.87,频率因子A=1.995×1019。芳基乙炔树脂的加压固化温度为110～115℃,其起始固化温度为115℃。固化工艺为:115℃/8h+120℃/8h+140℃/2h+160℃/2h+180℃/2h+200℃/2h+220℃/4h。芳基乙炔树脂凝胶前固化过程由化学反应控制,凝胶后属于扩散控制,因此在凝胶时需延长固化时间。     

酚醛改性聚芳基乙炔基复合材料探索

聚芳基乙炔（PAA）树脂具有残碳率高、吸水率低、固化反应为加聚反应、无低分子物副产物逸出等特点,是专为新一代树脂基热防护复合材料而研制的。但其与碳布的浸润性及粘接性能差,碳布增强复合材料的剪切强度较低。本文采用酚醛树脂对PAA树脂进行改性处理,在不降低残碳率的情况下,明显改善了PAA树脂与碳布的粘接性能。改性后碳／聚芳基乙炔复合材料的剪切强度由5．5MPa提高到11MPa以上。     

4，4＇-二炔丙氧基二苯醚与二乙炔基苯共聚合及其共聚物性能研究

通过4,4＇-二炔丙氧基二苯醚与二乙炔基苯共聚制备改性聚芳基乙炔树脂（MPAA）,并对工艺性能、浇铸体热性能及其复合材料的力学性能进行研究。DSC研究表明,MPAA有效降低了PAA树脂的固化热,MPAA具有良好的工艺性能;TGA、DMA结果表明,固化MPAA与PAA相比,脆性得到改善,仍具有较好的热稳定性,MPAA在800℃时的残碳率为76％。MPAA树脂基复合材料的力学性能比PAA树脂有明显提高,230℃下弯曲强度保留率为82％。     

4,4''''-二炔丙氧基二苯醚与二乙炔基苯共聚合及其共聚物性能研究

通过4,4'-二炔丙氧基二苯醚与二乙炔基苯共聚制备改性聚芳基乙炔树脂(MPAA),并对工艺性能、浇铸体热性能及其复合材料的力学性能进行研究,DSC研究表明,MPAA有效降低了PAA树脂的固化热,MPAA具有良好的工艺性能;TGA、DMA结果表明,固化MPAA与PAA相比,脆性得到改善,仍具有较好的热稳定性,MPAA在800℃时的残碳率为76%.MPAA树脂基复合材料的力学性能比PAA树脂有明显提高,230℃下弯曲强度保留率为82%.     

碳布增强聚芳基乙炔新型防热材料

本文研究了新型高碳聚芳基乙炔树脂(PAA)的成碳率及其碳布增强防热材料(2DC/PAA)成型工艺,对复合材料的性能进行了表征.结果表明,聚芳基乙炔树脂的成碳率高于酚醛树脂,C/PAA材料烧蚀性能优异,氧-乙炔线烧蚀率0.004mm/s;但材料机械性能较低,剪切强度仅为5.8MPa.     

芳基乙炔树脂复合电纺纳米纤维的制备及其形貌研究

由二乙烯基苯经过溴化加成-脱溴化氢制备芳基乙炔,将芳基乙炔进行预聚得到一定粘度的芳基乙炔预聚物。采用静电纺丝制备了芳基乙炔预聚物/PAN复合电纺纤维。将复合纤维在250℃下进行热处理,然后在氮气氛中煅烧。用FESEM、FTIR分析了复合纤维的形态和化学结构的变化。结果表明,当芳基乙炔预聚物与PAN质量比为1时,复合纤维经过热处理后能保持纤维形状,预聚时引发剂AIBN的引入更有利于复合纤维碳化后保持纤维形状,经900℃煅烧后复合纤维为PAA/碳纳米纤维。     

聚芳基乙炔树脂及其复合材料的研究现状

聚芳基乙炔具有杰出的耐高温性能,可作为热防护材料的基体树脂,并且其碳纤维／PAA复合材料的耐烧蚀性能和可靠性远远高于传统的碳／酚醛,其耐高温性能优于当前性能最好的聚酰亚胺（PI）,结构稳定性和吸湿性远优于环氧树脂,因此在航天器部件方面有很大应用潜力。主要介绍了聚芳基乙炔的单体、合成方法、性能特点、改性及其复合材料的研究进展和发展前景。     

聚酰胺酸对环氧树脂胶膜固化反应的影响及其机理

以液体环氧树脂与固体环氧树脂混配,4,4′-二氨基二苯砜(DDS)为固化剂,加入聚酰胺酸(PAA)对固液混配环氧树脂进行改性,采用刮膜法制备环氧树脂胶膜.通过DSC分析、平板拉丝法和傅里叶转换红外光谱法,研究了环氧树脂固液比、PAA用量等对环氧树脂胶膜成膜性、同化温度和同化速率的影响,并探索了PAA对环氧树脂/DDS体系固化反应的作用机理.结果表明,PAA可提高环氧树脂胶膜韧性,可降低固化温度,加快固化速度.对于环氧树脂(固/液质量比为50/50)/DDS/PAA体系,当PAA质量分数5%时,同化起始温度由未加PAA时的175.9℃下降到138.8℃,140℃时的固化凝胶时间由162 min下降到46 min,体系由高温固化变为近中温固化.     

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。