酚醛树脂的改性及其浸渍石墨性能

为了解决酚醛树脂因浸渍石墨后黏度增大而失效的问题,以氯化锌作为催化剂,用糠醇对黏度过大的酚醛树脂进行改性。并分别以失效酚醛树脂、普通酚醛树脂和改性酚醛树脂作为浸渍剂,在0.7MPa、180℃的条件下对普通中密度石墨进行了4次浸渍固化操作,测试了浸渍剂的黏度变化并对浸渍固化后的石墨进行了微观结构、开孔气孔率、增重率、热重、抗压强度以及耐腐蚀性等表征分析。结果表明,当酚醛树脂、糠醇和Zn Cl_2的质量比为100∶40∶2时,改性酚醛树脂的黏度适中,浸渍石墨的耐高温性能最好;并且使用改性酚醛树脂浸渍的石墨具有更好的填孔效率,只需要2次浸渍就能达到最好的浸渍效果,与失效酚醛树脂浸渍的石墨相比增重率提高了2%,抗压强度和耐碱性也有一定提升。     

高性能改性酚醛树脂胶粘剂的研究

利用钼改性酚醛树脂，对改性后树脂的综合性能进行正交分析，确定最佳工艺条件为：以盐酸为催化剂，用量为苯酚质量的0．5％，反应温度为90℃，反应时间3．5h。并对钼酚醛树脂进行了TG分析，改性后树脂固化温度在160℃左右，热分解温度为531．8℃，600℃下的热失重率为17．5％，可知钼酚醛树脂的热分解温度和耐热性比普通酚醛树脂要高。     

石墨换热设备浸渍工艺探讨

为了保证石墨换热设备的安全质量,一般通过浸渍的方法将石墨件制成不透性石墨材料,浸渍剂性能的优劣和浸渍固化工艺决定了石墨件的力学性能。本文选择酚醛树脂、改性酚醛树脂两种浸渍剂,进行工艺性试验,通过比较其抗拉强度、抗弯强度、抗压强度性能指标,确定改性酚醛树脂的浸渍性能好于酚醛树脂,同时也验证了浸渍工艺的正确性。     

固化温度对酚醛树脂浸渍石墨性能的影响

以热固性酚醛树脂为浸渍剂,在0.7 MPa下对普通中密石墨样品进行加压浸渍,并在130,150,180,200℃下分别进行固化,每个固化温度下进行3次浸渍固化操作;对浸渍石墨进行了孔隙率、增重率、抗压强度以及热重等表征分析。结果表明,在130℃下固化的浸渍石墨增重率高,孔隙率低,抗压强度低,耐高温性能差;在200℃下固化的浸渍石墨孔隙率高,抗压强度较高,质量稳定,耐高温性能好。     

酚醛树脂浸渍石墨的热稳定性研究

在常温常压的条件下,以酚醛树脂浸渍M120碳石墨材料,研究了不同固化温度条件下浸渍石墨的增重率、开孔气孔率、肖氏硬度及抗折强度等基本性能,并通过马弗炉和热重分析仪分析其热稳定性。结果表明,160℃固化条件下的浸渍石墨试样的基本物理性能最优(增重率最高,开孔气孔率最低,肖氏硬度最高),140℃固化条件下的浸渍石墨试样抗折强度最高,具有优异的热稳定性。酚醛树脂浸渍石墨在0~450℃热稳定性较好,在450℃以上时,浸渍石墨开始分解,热稳定性差。     

浸渍固化次数对酚醛树脂浸渍石墨性能影响

为探究不同浸渍固化次数对酚醛树脂浸渍石墨性能的影响,以热固性酚醛树脂为浸渍剂,在160℃、0.72 MPa条件下对普通中密石墨分别进行不同次数浸渍固化处理,并对浸渍固化后的石墨进行了偏光显微镜、密度、增重率、开孔气孔率、热重和抗压强度等表征分析,以比较不同浸渍固化次数下石墨的性能。结果表明:石墨的密度、增重率和抗压强度随着浸渍固化次数的增加而升高,开孔气孔率和耐高温性能则随浸渍固化次数的增加而降低。从缩短生产周期、降低生产成本和提高经济效益的角度出发,在满足石墨耐高温性能和抗压强度的使用条件下,只需对石墨进行3次浸渍固化处理;若对石墨的抗压强度有更高的要求,则需对石墨进行不少于4次的浸渍固化处理。     

石墨换热设备浸渍工艺探讨

为了保证石墨换热设备的力学性能,一般通过浸渍的方法将材料制备成不透性石墨材料,浸渍剂性能是影响石墨换热设备性能的关键因素。采用酚醛树脂、改性酚醛树脂两种浸渍剂进行工艺性试验,通过比较其抗拉强度、抗弯强度、抗压强度性能指标可以确定,改性酚醛树脂的浸渍性能优于酚醛树脂,在实际生产过程中可以根据用户的需求,优先选用改性酚醛树脂,同时也验证了浸渍工艺的正确性。     

热处理改性石墨的嵌锂行为

通过浸渍的方法在天然鳞片石墨的表面包覆上一层酚醛树脂,然后在N2保护下于600℃-1000℃炭化1h制得改性石墨。应用TG－DTA法研究了酚醛树脂的热失重行为;SEM,XRD及恒电流充放电等技术研究了所得改性石墨的表面物理形态、微晶结构及恒电流充放电性能。结果表明包覆在石墨表面的具有无定形结构的酚醛树脂炭能够有效阻止石墨在充放电过程中发生层状剥落,从而提高了石墨的循环稳定性。     

连续碳纤维增强热固性酚醛树脂复合材料的3D打印工艺及性能研究

针对连续碳纤维增强热固性酚醛树脂复合材料3D打印成型工艺的技术难题,本文提出了浸渍-原位预固化-后固化的3D打印成型方案,实现了连续碳纤维增强热固性酚醛树脂复合材料的3D打印成型,并研究浸渍温度对酚醛树脂接触角与表面张力,以及打印工艺对样件形貌和力学性能的影响规律。结果表明:当浸渍温度为40 ℃,预固化温度为180 ℃时,纤维-树脂界面结合效果最佳,原料具备成型条件;当打印间距为0.5 mm时,样件的弯曲强度及模量达到最大值,分别为660.00 MPa和57.99 GPa,层间剪切强度达到20.14 MPa。此连续碳纤维增强热固性酚醛树脂复合材料一体化制备工艺解决了3D打印热固性树脂原位成型难的问题,为制备具有复杂结构的连续纤维增强热固性树脂复合材料提供了参考。     

合成树脂浸渍含量对炭素机械密封材料性能的影响

主要研究酚醛树脂的浸渍含量对炭素机械密封材料的机械,物理性能的影响,同时对炭石墨材料浸渍酚醛树脂的浸渍机理及酚醛树脂固化机理作了初步的探讨。     

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。