工况条件对PI/PTFE复合材料自润滑性能的影响

为了考察聚酰亚胺/聚四氟乙烯(PI/PTFE)基复合材料的摩擦学适应性,研究了不同工况条件对PI/PTFE复合材料和金属试件对磨时摩擦学性能的影响。实验结果表明,法向接触载荷对复合材料的耐磨性和减摩性的影响具有一致性,随着法向接触载荷的增大,摩擦因数和磨损率均逐渐减小。滑动速度对复合材料的减摩性的影响比较复杂,呈现出先减小然后增大再减小的变化趋势,与此相对应的是复合材料耐磨性则表现出逐渐增大的趋势。对试件磨损形貌分析表明,在中等或较高载荷下,复合材料表面主要以塑性流动为主,黏附磨损是其主要的磨损形式;在较高滑动速度下,复合材料的磨损则表现为微切削和黏附磨损。     

腐蚀环境中纤维增强聚四氟乙烯复合材料的摩擦磨损性能研究

分别研究了不同含量碳纤维(CF)、玻璃纤维(GF)填充聚四氟乙烯（PTFE）复合材料在硫酸溶液中和干摩擦条件下的摩擦学性能,同时考察了PTFE复合材料在酸中的腐蚀行为,探讨了相关机理。结果表明,在酸中GF能够提高PTFE的耐磨性,比CF在提高PTFE耐磨性方面具有更好的优势。就酸溶液中的耐磨性和耐腐蚀性而言,15 %（质量分数,下同）是填料的最佳含量,此时GF和CF填充的PTFE,耐磨性分别较纯PTFE提高了7.7和4.4倍;当填料的含量超过15 %时,复合材料的耐磨性和耐腐蚀性均下降,主要是由于此时犁削和磨粒磨损是PTFE复合材料的主要磨损机制。由于酸溶液的冷却和润滑作用,硫酸溶液中PTFE复合材料的摩擦因数大幅降低,但酸溶液抑制了对磨面上转移膜的形成。     

表面处理纳米Al2O3填充PTFE复合材料的磨粒磨损性能

利用自制销-盘式磨粒磨损试验机，测定聚四氟乙烯(PTFE)及其表面处理与未处理纳米氧化铝(Al2O3)填充聚四氟乙烯复合材料试件在干摩擦滑动条件下的磨粒磨损质量损失。考察了载荷、磨粒、转速等参数的变化对试件摩擦学性能的影响。采用扫描电子显微镜观察、分析试件磨损表面形貌及磨损机理。结果表明，纳米Al2O3可以提高PTFE耐磨性。表面处理纳米Al2O3在PTFE中能较均匀分散，其耐磨性比相同含量但未经表面处理的纳米Al2O3填充PTFE高。导致PTFE复合材料磨粒磨损的重要机理是犁切破坏。     

PI填充PTFE复合材料

采用金属粉末冶金法制备聚酰亚胺(PI)填充聚四氟乙烯(PTFE)复合材料,考察不同PI填充量对复合材料力学性能和摩擦学性能的影响。结果表明,随着PI填充量的增加,复合材料的拉伸强度和断裂伸长率均下降,但压缩强度提高。采用PI填充PTFE,可以使耐摩擦性能提高2个数量级,摩擦系数稍有提高,磨损表面的扫描电子显微镜显示,PI填充PTFE对提高材料耐磨性能效果非常明显。对采用国产PI与进口PI填充PTFE制备的复合材料性能进行对比,发现国产PI完全可以替代进口同类产品。     

纳米TiO2对PTFE基复合材料磨粒磨损性能的影响

利用自行改制的销-盘式磨粒磨损试验机测定纳米TiO2用量对聚四氟乙烯（PTFE）复合材料试件在干摩擦滑动条件下的磨粒磨损性能。考察了载荷、磨粒、转速等参数的变化对试件摩擦学性能的影响。结果表明，在实验条件下，纳米TiO2／PTFE复合材料的抗磨粒磨损性能，以纳米TiO2质量分数为2％时，填充PTFE复合材料抗磨损性能最好。随纳米TiO2用量的增大，抗磨损性能有所减弱。在载荷、磨粒、转速等参数的变化对PTFE复合材料耐磨性的影响中，磨料粒度对磨损的影响最大，转速的影响最小。     

酸性溶液中PTW增强PTFE复合材料的耐蚀性和摩擦磨损性能

分别研究了不同含量钛酸钾晶须(PTW)、碳纤(CF)填充聚四氟乙烯(PTFE)复合材料在硫酸溶液中和干摩擦条件下摩擦学性能以及酸中的耐蚀性能,借助SEM等分析探讨了相关机理。结果表明,酸中纯PTFE耐磨性较干摩擦条件下提高了2个数量级,摩擦系数也只有干摩擦的15.3%。与CF/PTFE相比,PTW/PTFE复合材料在酸中显示更好的耐蚀和耐磨性能。PTW可以进一步提高PTFE酸中耐磨性能、降低摩擦系数。含15%（质量）PTW时复合材料具有最低的磨损率,此时比纯PTFE酸中耐磨性提高13.8倍,是相同含量CF/PTFE耐磨性的3.2倍。由于酸溶液的冷却和润滑作用,复合材料的摩擦系数与干条件相比明显降低。然而,酸溶液阻止了转移膜的形成。不管是干摩擦还是在酸性溶液中,当填料含量超过15%（质量）时,犁削和磨粒磨损是PTFE复合材料的主要磨损机理。     

碳纤维改性POB/PTFE基超声电机耐磨涂层

利用喷涂方法制备不同配比碳纤维(CF)改性聚苯酯(POB)/聚四氟乙烯(PTFE)基超声电机定子耐磨涂层,研究CF的质量分数对POB/PTFE基复合材料涂层的硬度、附着力、摩擦学性能的影响,并通过扫描电子显微镜观察涂层表面磨损形貌并讨论其磨损机理。结果表明:POB和CF均能提高PTFE基复合材料涂层的硬度及耐磨性;涂层的附着力随着CF质量分数的增加先增大后减小。在文章研究范围内,当CF质量分数为10%时,涂层的磨损率最低,且使用该摩擦材料时,超声电机的堵转力矩和空载转速均较高,电机的综合性能较优。     

纳米TiO2/PTFE复合材料的干摩擦磨损性能

利用磨损试验机、扫描电子显微镜等方法研究了表面处理与未处理纳米TiO2(质量分数为6％)填充聚四氟乙烯(PTFE)复合材料的干摩擦性能。结果表明，纳米TiO2能明显提高：PTFE耐磨性并改变其磨屑形成机理。表面处理纳米TiO2在PTFE中能较均匀分散。纳米TiO2填充PTFE复合材料的摩擦系数比PTFE稍大，纳米TiO2表面处理与否对PTFE复合材料的摩擦系数影响不大，但表面处理纳米TiO2填充聚四氟乙烯耐磨性比PTFE有显著提高，表面处理与表面未处理纳米TiO2填充PTFE复合材料的耐磨性比PTFE可分别提高7倍和3倍左右。导致PTFE磨损的重要机理是粘着磨损。     

PHB与纳米Cu对PTFE/GF复合材料摩擦学性能的影响

考察了聚苯酯(PHB)与纳米铜(Cu)协同改性对聚四氟乙烯/玻纤(PTFE/GF)复合材料摩擦磨损性能的影响,探讨了复合材料的磨损表面形貌及磨损机理.结果表明,当PHB质量分数为6％时,PTFE/GF/PHB复合材料的摩擦因数最低,达到0.175,但磨损率较大,为6.84×10-6mm3/(N·m).在此基础上,采用PHB与纳米Cu复合改性PTFE/GF复合材料,当纳米Cu质量分数为0.3％和PHB质量分数为6％时,复合材料的摩擦学性能最佳,摩擦因数为0.194,磨损率仅为1.60×10-6mm3/(N·m).纳米Cu的加入使复合材料的摩擦因数能较早达到平稳阶段.SEM分析表明,PTFE/GF复合材料表现为严重的磨粒磨损,磨损表面出现深且宽的犁沟;与PTFE/GF复合材料相比,PTFE/GF/PHB复合材料磨粒磨损得到极大改善,磨粒磨损程度大大减小;PTFE/GF/6％ PHB/0.3％纳米Cu复合材料的磨损面更加光滑平整,表现为极轻微的磨粒磨损,耐磨性最好.     

偶联修饰纳米碳化硅/聚四氟乙烯基复合材料的摩擦磨损性能

通过冷压烧结法制备了聚四氟乙烯(PTFE)与钛酸酯和硅烷偶联剂修饰的纳米碳化硅(nano-SiC)复合材料,采用45#钢为摩擦对偶件的MM-200型摩擦磨损试验机,在室温干摩擦条件下测试了复合材料的摩擦学性能,用扫描电子显微镜(SEM)对磨损表面进行了观察并分析了磨损机理。结果表明:纳米SiC的加入能提高PTFE复合材料的硬度和耐磨性;偶联修饰改善了复合材料的摩擦学性能;与硅烷相比,钛酸酯偶联修饰nano-SiC/PTFE复合材料的硬度和摩擦学性能更好。两种偶联修饰复合材料的表面磨损情况相似,主要表现为粘着磨损,而未经偶联处理nano-SiC的复合材料在粘着磨损的同时出现了疲劳磨损。     

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.