PTFE乳液制备PTFE/YSZ微孔膜及孔隙率的研究

以聚四氟乙烯（PTFE）乳液为原料、氧化钇稳定二氧化锆（YSZ）微纳米粉体为增强体,采用机械拉伸法制备了PTFE/YSZ复合微孔膜,通过扫描电子显微镜对其进行了表征,并运用单因素法探讨了分散剂聚乙烯醇（PVA）、拉伸倍数、YSZ含量和热处理温度对复合微孔膜孔隙率的影响。结果表明,在复合微孔膜中添加PVA以及增加YSZ含量均使复合微孔膜的孔隙率增大;在拉伸3.5倍、YSZ含量为8 %(质量份数)、热处理温度为320 ℃时,复合微孔膜孔隙率高达73.09 %。     

UHMWPE微孔膜的制备工艺对膜性能的影响

基于热致相分离(TIPS)原理,研究了锂离子电池隔膜用超高分子量聚乙烯(UHMWPE)微孔膜的制备工艺及其对微孔膜结构的影响,探索了不同平均分子量对加工成型性的影响,当铸片辊温度分别为20、30、50℃时,铸片辊温度对UHMWPE厚片后续拉伸工艺性的影响,在纵向拉伸倍率为6,横向拉伸倍率分别为4、5、6的条件下,拉伸倍率对微孔膜微观形态的影响,以及热定型时间对UHMWPE微孔膜结构的影响,同时,对UHMWPE微孔膜热致相分离(TIPS)成型机理进行了分析,优化了微孔膜的制备工艺,获得了UHMWPE微孔膜制备过程中微孔膜的结晶形态及结构的变化规律,为制备满足锂离子电池使用要求的UHMWPE微孔膜奠定了基础。     

PTFE/ZrO2复合微孔膜结晶性能的研究

以聚四氟乙烯（PTFE）乳液为原料,选定化学稳定性、热稳定性优异的纳米二氧化锆（ZrO2）为增强剂,制备出PTFE/ZrO2复合微孔膜,并通过X射线衍射仪对PTFE/ZrO2复合微孔膜样品的结晶性能进行了表征,使用单因素法讨论了ZrO2的含量、拉伸倍数、热处理温度及热处理时间等因素对PTFE/ZrO2复合微孔膜结晶性能的影响。结果表明,复合微孔膜的结晶度与拉伸倍数、热处理温度和热处理时间成正比,与ZrO2含量成反比;ZrO2含量为7 %、拉伸倍数为1~2.5倍、热处理温度为310 ℃、热处理时间为10 min时,制成的复合微孔膜综合性能最佳。     

PTFE乳液制备PTFE/ZrO2微孔膜及性能研究

尝试以聚四氟乙烯（PTFE）乳液为原料制备PTFE微孔膜,选定化学稳定性、热稳定性优异的纳米二氧化锆（ZrO2）作为增强剂以提高微孔膜强度,采用电子万能力学试验机测试了样品的力学强度,用单因素法讨论了纳米ZrO2含量、拉伸比例、热处理温度和热处理时间对微孔膜拉伸强度的影响;同时采用低温等离子体处理PTFE/ZrO2复合微孔膜以改善其表面亲水性。结果表明,PTFE/ZrO2复合微孔膜的拉伸强度与纳米ZrO2含量成正比,与拉伸倍数成反比;其拉伸强度随着热处理温度的升高或热处理时间的延长,呈先增大后减小的变化趋势,分别在310 ℃和10 min时出现最大值;低温等离子体处理的最佳时间为30 s。     

聚四氟乙烯拉伸微孔膜制备工艺探索

介绍了聚四氟乙烯拉伸微孔膜的制备方法、成孔机理及结构特征;对国内外聚四氟乙烯拉伸微孔膜加工工艺研究进展进行了归纳总结,并指出了不同工艺参数下制备的膜材料的特征及性能;展望了聚四氟乙烯拉伸微孔膜的发展前景。     

拉伸倍率对膨体聚四氟乙烯多孔膜的结构影响研究

膨体聚四氟乙烯多孔膜,由于其独特的性质,在诸多领域得到应用。该薄膜的加工方式复杂特殊,工艺的细微差别将导致产品的结构和性能的显著变化。在本工作中,作者考察了拉伸倍率对微孔膜微观结构和透气性能的影响,期望为推动聚四氟乙烯多孔膜行业发展贡献绵薄之力。     

聚四氟乙烯微孔膜的研究进展

聚四氟乙烯（PTFE）微孔膜具有独特的纤维—＂结点＂微观结构,不仅具有良好的化学稳定性、热稳定性、抗腐蚀等性能,还具有高透光率、防水、透气等特性。PTFE微孔膜主要采用机械拉伸法制备。本文综述了近年来PTFE微孔膜的制备工艺、形成机理,详细阐述了填充、接枝等改性方法的研究进展以及其在化工、建筑、医学等领域应用的最新研究成果,并指出目前存在的问题,对今后的研究提出了展望。     

拉伸工艺对无机微粉PET反射膜性能的影响

在聚对苯二甲酸乙二醇酯(PET)树脂中加入无机微粉填充剂硫酸钡(BaSO4),利用流延拉伸法制备了PET反射膜;通过紫外可见光分光光度计、镜像光泽度计、示差扫描量热仪(DSC)等测试仪器研究了拉伸温度、拉伸倍率及拉伸速率对无机微粉PET反射膜的反射性能、光泽度及结晶性能的影响。研究结果表明,拉伸温度为90℃、拉伸倍率为4倍、拉伸速率为400 mm/min时,能获得高反射率、较好光泽度的反射膜;拉伸使得膜的玻璃转变温度升高,冷结晶峰减小且向低温方向移动,结晶度增加。     

定向拉伸对PTFE/BaSO4复合材料性能和结构的影响

采用冷压和自由烧结工艺制备硫酸钡（BaSO4）填充聚四氟乙烯（PTFE）密封材料,并对其进行了拉伸处理。研究了不同拉伸倍率对PTFE/BaSO4复合材料的密度、压缩回复率的影响,并通过高温差示热分析仪和X射线衍射仪分析了拉伸处理对PTFE/BaSO4复合材料熔融结晶行为以及PTFE晶态结构的影响。结果表明,随着拉伸倍率的增加,PTFE/BaSO4复合材料的压缩率大幅提高,回复率降低,总体弹性回复率提高。拉伸处理对PTFE/BaSO4复合材料熔融结晶行为的影响不大,并且PTFE的晶型不变,随着拉伸倍率的增加,结晶度呈现先减小后增大的趋势。     

拉伸工艺参数对PP/Talc微孔复合材料性能的影响

利用滑石粉(Talc)填充改性聚丙烯(PP)基体,采用固态口模拉伸法成功制备了聚丙烯/滑石粉微孔复合材料,研究了拉伸速率和拉伸温度等工艺参数对微孔复合材料的密度、耐热性、力学性能和微观结构的影响.研究结果表明,固态口模拉伸后,大量滑石粉粒子周围存在沿拉伸方向的微孔,聚丙烯基体发生取向,形成纤维状结构.提高拉伸速率,能够...     

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。