基于双转子连续混炼挤出机的PPS/CF复合材料制备及性能研究

采用双转子连续混炼挤出机并通过熔融共混法制备了碳纤维(CF)增强聚苯硫醚(PPS)复合材料,并对其微观形貌、动态力学性能、力学性能和导电性能进行了研究,且对相关的影响因素进行了分析。结果表明,适当降低挤出机转子转速、提高CF含量可以改善PPS/CF复合材料的力学性能和导电性能;当转子转速为200r/min时,采用含量为20 % (质量分数,下同)的CF制得的PPS/CF复合材料的冲击强度达到49.94 J/m,体积电阻率达到60.65 Ω·cm,均优于纯PPS。     

PPS/PAI/CF复合材料摩擦磨损性能的研究

采用模压成型法制备了聚苯硫醚(PPS)/聚酰胺酰亚胺(PAI)合金及其碳纤维(CF)改性复合材料。测试分析了该复合材料的力学性能,并通过扫描电镜(SEM)对其摩擦磨损表面形貌进行了观察,探讨了复合材料的摩擦磨损性能;考察了PPS/PAI合金的最优配比及CF含量对PPS/PAI/CF复合材料性能的影响。结果表明:PAI的加入改善了PPS的力学性能,当PPS/PAI质量比为40/60时,PPS/PAI合金的力学性能最优;另外,CF的加入使PPS/PAI/CF填充复合材料的摩擦系数和磨损量大幅度下降,其中,当CF含量为30%时,PPS/PAI/CF填充复合材料的摩擦系数和磨损量较未填充PPS/PAI分别下降了66%和90%。     

碳纳米管含量对聚酰亚胺/碳纤维复合材料性能的影响

以聚酰亚胺(PI)为基体、碳纤维(CF)和碳纳米管(CNTs)为复合增强体,采用热模压工艺制备了不同CNTs含量的PI/CF/CNTs复合材料。采用电子拉力机、动态热机械分析仪和热重分析仪研究了PI/CF/CNTs复合材料的力学性能、动态力学性能和热稳定性。结果表明,与未加CNTs的PI/CF复合材料相比,CNTs含量为PI质量的0.2%时,PI/CF/CNTs复合材料具有最佳的常温力学性能,其中常温拉伸强度提高19.5%,常温弯曲强度提高20.6%,常温层间剪切强度提高14.7%,玻璃化转变温度则由357℃提高到451℃;CNTs含量为PI质量的0.05%时,PI/CF/CNTs复合材料具有最佳的高温力学性能,其中400℃拉伸强度提高15.8%,400℃弯曲强度提高9.6%,400℃层间剪切强度提高12.8%。CNTs的添加对PI/CF/CNTs复合材料的热稳定性几乎没有影响。     

CF/CNTs多尺度混杂填充PA6复合材料性能研究

以碳纤维/碳纳米管(CF/CNTs)多尺度混杂填充聚酰胺6(PA6)复合材料为研究对象,采用不同的方法处理CNTs,并考察了对应复合材料的力学性能、导电性能和导热性能。结果表明:CNTs经过表面化学镀镍处理后,明显改善了CF与基体界面间的结合强度和相容性。表面镀镍处理的碳纳米管(CNTs-Ni)吸附在CF表面,不仅可促进CF与基体间形成"钉扎效应",从而提高了复合材料的力学性能,还在CF与PA6基体间形成了导热桥路和导电网络,使材料的电阻率和界面热阻有所下降;CF和CNTs混杂填充基体树脂对复合材料的力学性能、导热性能及导电性能有着良好的协同增效作用;CNTs-Ni可明显改善CF增强复合材料的导热性能和导电性能。     

碳纳米管对酚醛树脂/碳纤维复合材料力学性能的影响

利用碳纳米管(CNTs)对酚醛树脂(PF)进行改性,研究了CNTs含量对PF/碳纤维(CF)复合材料力学性能的影响。研究表明,CNTs能够明显提高PF/CF复合材料的力学性能,当CNTs的含量为0.5%时,复合材料的弯曲强度达到最大值(891.8MPa),与未加入CNTs时相比提高了168.4MPa,而弯曲弹性模量降低了9.5GPa;当CNTs的含量为1.5%时,复合材料的压缩强度、层间剪切强度、冲击强度均达到最大值,与未加入CNTs时相比,分别提高了10.4%、79.2%、71.9%。     

碳纳米管/碳纤维混杂多尺度增强体研究现状

碳纳米管(CNTs)优异的力学性能使其成为复合材料的理想增强材料,将CNTs引入到碳纤维(CF)表面制备CNTs/CF纳、微米复合增强体,可同时改善复合材料的界面剪切强度和冲击强度,从而获得具有优异综合性能的复合材料。本文综述了CNTs/CF混杂多尺度增强体的制备方法及其复合材料的性能。     

PE-HD/CF/HGB三元复合材料的制备及力学性能

以高密度聚乙烯(PE-HD)为基体、碳纤维(CF)为增强材料,采用双辊塑炼工艺制备了PE-HD/CF复合材料,力学性能测试结果表明该复合材料的拉伸和弯曲性能随CF含量的增加而增大,但缺口冲击强度逐渐下降。在该复合材料基础上添加空心玻璃微珠(HGB)制得PE-HD/CF/HGB三元复合材料,力学性能测试结果表明当HGB用量为10份且CF用量为15份时,三元复合材料的拉伸强度、弯曲强度和缺口冲击强度均达到最大,分别为46.98 MPa,45.69 MPa和8.17 kJ/m2,较未加HGB的PE-HD/CF复合材料分别提高了7.19%,4.17%和10.4%。扫描电子显微镜结果表明,HGB主要通过其变形和破坏来吸收冲击能量,从而提高复合材料的韧性。     

高导电、低逾渗PLA/CNTs导电复合材料的结构设计及性能研究

通过溶液吸附?熔融法制备了具有低逾渗高导电性能的左旋聚乳酸/右旋聚乳酸/碳纳米管(PLA/PDLA/CNTs)复合材料。在PLA/CNTs复合材料内部通过添加PDLA以提高复合材料的结晶性能,起到良好的体积排斥作用,促进了CNTs的分散,对PLA/PDLA/CNTs复合材料的导电网络结构进行有效调控;随着PDLA含量的增加,PLA/PDLA/CNTs复合材料的导电性能表现出了先增加后降低的趋势,当PDLA的含量仅为0.2%时,PLA/0.2%PDLA/0.6%CNTs的电导率从10^-6 S/m提升到了10^-4 S/m,提高了2个数量级,并且复合材料的导电逾渗值从0.58%(PLA/CNTs)降低到0.45%(PLA/PDLA/0.6%CNTs)。此外,CNTs和PDLA的引入可以有效的提高复合材料的结晶性能和复数黏度,相比于纯PLA,PLA/0.5%PDLA/0.6%CNTs的开始结晶温度(T_o)和最大峰结晶温度(T_p)分别提高了30.6℃和20.8℃。通过力学性能数据分析发现,在CNTs和PDLA...     

PA6/CF/EG导电复合材料的制备与性能

采用熔融共混法制备了不同碳纤维/热膨胀石墨(CF/EG)比例的尼龙6/碳纤维/热膨胀石墨(PA6/CF/EG)导电复合材料并研究其性能。结果表明,CF的加入能显著提高复合材料的力学性能;而随着EG含量的提高,复合材料的导电性能和导热性能显著提高,但力学性能在一定程度上得到降低。当CF质量分数为20%时,复合材料具有最优的力学性能,当EG质量分数为20%时,复合材料体积电导率可显著提高至0.262 S/m,热导率可达1.3379W/(m·K)。     

PU/CNTs复合材料的制备及其在室内设计中的应用

分别采用物理共混法和化学偶联法原位制备了聚氨酯(PU)/碳纳米管(CNTs)复合材料,并研究了其力学性能和抗静电性能。结果表明:采用化学偶联法制备的PU/CNTs复合材料中的CNTs分布更均匀,且复合材料的力学性能更优异;随CNTs含量增加,PU/CNTs复合材料的断裂伸长率逐渐增大,而拉伸强度和冲击强度先增加后降低;当w(CNTs)为0.4%时,复合材料的拉伸强度最高,w(CNTs)为0.6%时,其冲击强度最高;随CNTs含量增加,PU/CNTs复合材料的抗静电性能得到改善,保温性能无明显降低,是较为理想的室内设计材料。     

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。