聚乳酸增韧改性研究进展

主要介绍了聚乳酸的化学增韧改性(共聚改性)和物理增韧改性(增塑、共混与无机刚性粒子复合),综述了近年来国内外聚乳酸增韧改性的研究现状及进展,并对今后聚乳酸增韧改性提出了建议。     

聚乳酸增韧研究进展

总结了聚乳酸增韧改性方面的最新研究进展,为新型聚乳酸复合材料的研究开发提供理论依据;概述了共混、复合、共聚、交联、增塑以及添加成核剂等几种增韧技术,并比较了不同增韧方法的特点;通过对合成方法的改进以及进行共混、共聚、复合及增塑等改性,可以显著改善聚乳酸材料的力学性能并同时保持耐热性和降解性能不受影响;开发更加高效的增韧改性剂,增加其与聚乳酸分子链间的界面相互作用并提高复合材料的冲击性能已成为研究工作的努力方向。从微观分子尺度上对聚乳酸进行增韧改性以及设计绿色合成路线仍是目前研究工作的重点。     

PLA熔体强度的提高及其增韧改性研究

综述了聚乳酸(PLA)作为吹膜材料所存在的缺点。同时分析和总结了提高PLA熔体强度和韧性的方法和机理,指出:提高熔体强度的改性方法包括共聚改性和支化反应;增韧改性方法可概括为增塑改性、共混改性和复合改性。     

双马来酰亚胺树脂改性研究进展

综述了双马来酰亚胺增韧改性的研究进展,介绍了各种改性方法及其机理.内容包括内扩链新型BMI合成改性、胺类扩链增韧改性、烯丙基系列化合物共聚增韧改性、橡胶共混增韧改性、热塑性树脂共混增韧改性、氰酸酯树脂增韧改性等几个方面.     

有机玻璃增韧改性的研究进展

综述了有机玻璃增韧改性的各种途径,包括共聚增韧、掺入第二相粒子共混增韧、采用互穿聚合物网络结构、双轴定向拉伸及复合工艺等,以及国内外研究的进展。     

PBT的增韧改性研究进展

结合聚对苯二甲酸丁二酯(PBT)的应用、结构与韧性特征,综述了近年来对PBT进行增韧改性的各种方法及其对共混物形态结构、力学性能等方面的影响,这些方法包括共聚增韧、弹性体增韧、与聚烯烃共混、核-壳共聚物增韧及热塑性工程塑料增韧等。并指出PBT的增韧改性方向是实现PBT的强韧化。     

接枝共聚法增韧改性聚氯乙烯树脂

综述了悬浮溶胀接枝共聚法、悬浮溶解接枝共聚法和悬浮低压接枝共聚法三种接枝共聚方法增韧改性聚氯乙烯树脂(PVC)的制备工艺,以及接枝共聚增韧改性PVC的结构特征和性能。接枝共聚法与共混法相比,明显改善了增韧改性剂和PVC之间的相容性,显著提高了增韧改性剂对PVC的增韧效果,表明了采用接枝共聚方法已成为增韧改性PVC的一种更有效的途径。     

抗冲聚丙烯的增韧机理和增韧方法研究进展

以提高聚丙烯的抗冲性能为背景,综述了得到普遍认可的银纹-剪切带理论和空穴理论增韧机理,物理改性(共聚共混改性、添加成核剂改性、填充改性)和化学改性(接枝改性、交联改性、化学共聚改性)增韧方法,指出了各改性方法的优缺点,并对抗冲聚丙烯未来发展前景进行了展望.     

PMMA增韧改性方法及机理

综述了聚甲基丙烯酸甲酯增韧改性的几种方法及机理,主要包括共聚增韧、共混增韧、形态控制增韧。     

聚乳酸复合材料增塑及增韧改性研究进展

简要介绍了聚乳酸(PLA)增塑改性的增塑机理,综述了近年来PLA增塑及增韧改性研究现状及进展,主要包括聚乙二醇、柠檬酸酯、植物油增塑改性PLA及柔性可降解树脂、弹性体、无机刚性粒子、植物纤维、淀粉等韧性材料共混增韧改性PLA,得出了PLA在增塑及增韧过程中存在的一些问题,如添加增塑剂改性或与柔性可降解树脂共混难以保证力...     

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.     

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。     

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.