Al2O3对导热硅橡胶性能的影响

考察了微米Al2O3的填充量及其粒径对甲基乙烯基硅橡胶导热性能及力学性能的影响,与纳米Al2O3填充硅橡胶进行了对比。结果表明:硅橡胶的导热系数随微米Al2O3填充量的增加而升高,但微米Al2O3填充量过大时,硅橡胶的力学性能和加工性能变差,最大填充量不宜超过220份。当微米Al2O3填充量小于100份时,大粒径Al2O3填充硅橡胶的导热性能优于小粒径Al2O3填充硅橡胶;当微米Al2O3填充量超过100份后,5μmAl2O3填充硅橡胶的导热性能优于50μmAl2O3填充硅橡胶;0·5μmAl2O3填充硅橡胶的导热性能始终低于5μm和50μmAl2O3填充硅橡胶;纳米Al2O3填充硅橡胶的导热性能明显优于微米Al2O3填充硅橡胶。小粒径Al2O3填充硅橡胶的力学性能优于大粒径Al2O3填充硅橡胶。与单一微米粒径的Al2O3填充硅橡胶相比,在高填充量(180份)下,50,5,0·5μm与50nm的AlO(质量比2∶5∶1∶1)混合填充硅橡胶呈现较高的导热性能和拉伸强度。     

氧化镁填充导热硅橡胶的性能研究

对氧化镁填充导热硅橡胶的性能进行研究.结果表明,氧化镁用量在200份以下时,小粒径氧化镁填充硅橡胶的热导率和拉伸强度大于大粒径氧化镁填充硅橡胶,而拉断伸长率则相反;大粒径氧化镁/小粒径氧化镁并用比为100/100时硅橡胶的热导率最大;添加适量的硅烷偶联剂有利于提高硅橡胶的热导率,其最佳用量约为大粒径氧化镁用量的0.5%.     

刚玉粉对室温硫化导热硅橡胶性能的影响

以α，ω-二羟基封端聚二甲基硅氧烷为基胶，刚玉粉为导热填料，制备了填充型室温硫化(RTV)导热硅橡胶。研究了刚玉粉的填充量、表面处理方式、粒径及不同粒径刚玉粉的配比对RTV导热硅橡胶性能的影响。结果表明：随着刚玉粉用量的增加，RTV硅橡胶的导热系数增大，但力学性能降低，基料的粘度增大，工艺性能变差，刚玉粉的用量以200份为宜；采用经表面处理的刚玉粉，可以改善其与基胶的相容性，提高RTV硅橡胶的导热性能；且采用硅烷偶联剂处理的刚玉粉还可提高RTV硅橡胶的力学性能；大粒径刚玉粉填充的RTV硅橡胶的导热性能优于小粒径刚玉粉填充的RTV硅橡胶，但力学性能下降；当填充量达到200份后，二者导热性能的差距明显缩小；不同粒径刚玉粉并用可以提高RTV硅橡胶的导热性能，降低基料粘度，改善工艺性能；当大粒径与小粒径刚玉粉的质量比为1／3或3／5时，所得RTV导热硅橡胶的综合性能较好。     

氧化锌/氧化铝对混炼型导热硅橡胶性能的影响

以二甲基乙烯基硅橡胶作为基胶,氧化锌、氧化铝为导热填料,乙烯基三甲氧基硅烷为表面处理剂,2,5-二甲基-2,5-双(叔丁基过氧基)己烷为固化剂制备导热硅橡胶;研究氧化锌、氧化铝对硅橡胶导热等性能的影响。结果表明,随着氧化锌用量的增加,硅橡胶的导热率、拉伸强度增大、硬度也随之增加,体积电阻率减小;氧化锌与氧化铝的质量比例为1∶1时,硅橡胶的综合性能最佳。     

氧化铝和碳化硅填充硅橡胶的导热性能研究

研究氧化铝和碳化硅填充硅橡胶的导热性能。结果表明:采用不同粒径碳化硅填充硅橡胶时,随着碳化硅用量的增大,硅橡胶的热导率逐渐增大;在相同填料用量下,粒径小的碳化硅填充硅橡胶热导率高于粒径大的碳化硅填充胶;氧化铝/碳化硅并用填充硅橡胶的导热性能优于单用氧化铝填充胶;当氧化铝/碳化硅质量比为8:2、填充量为600份时,硅橡胶的导热性能最佳。     

导热硅橡胶的老化性能研究

热老化是影响导热硅橡胶使用寿命的主要因素之一。该文分别采用氧化铝、氮化硼和石墨烯作为导热填料制备导热硅橡胶,研究其热老化性能。通过研究不同导热系数的导热硅橡胶复合材料热氧老化过程中交联密度和导热系数的变化,提出了不同导热系数的样品在热氧老化过程中导热系数变化的机理。     

Al2O3的表面处理及粒子尺寸对SBR导热橡胶性能的影响

以丁苯橡胶为基质，微米氧化铝与纳米氧化铝为导热填料，制备了填充型导热橡胶，研究了微米氧化铝填充量，偶联剂表面处理对导热橡胶导热性能的影响。比较了纳米氧化铝和微米氧化铝填充的导热橡胶的导热性能及物理机械性能。并将2种粒子以不同配比加入了苯橡胶基质中，对其影响进行了探讨。结果表明，随着微米氧化铝填充份数的增加，丁苯橡胶的导热系数增大，但共加工性能和物理机械性能下降；用硅烷偶联剂KH-570，KH-550，A-151和钛酸酯偶联剂TM-S105表面处理后的微米氧化铝对导热橡胶的导热性能有一定影响，但并不显著，在相同填充量下，纳米氧化铝填充的导热橡胶比微米氧化铝填充的导热橡胶具有更好的导热性能及物理机械性能；在合适的比例下，纳米氧化铝与微米氧化铝混合填充的导热橡胶其导热效果优于单纯使用微米粒子填充的橡胶。     

有机硅导热垫片性能的研究

以双组分室温硫化硅橡胶为基体树脂,Al₂O₃与Al(OH)₃为填料制备有机硅导热垫片。对垫片的导热性能、力学性能进行测试,并对影响渗油的因素进行分析。结果表明,随着填料量的增大,有机硅导热垫片的硬度、导热系数增大,渗油量减少;相同填料添加量时,官能团r[r=n(Si-Vi)/n(Si-H)]对渗油的影响较大,4种不同r值树脂制备垫片的渗油量随着r值增大而增大,当r=3.25时,甚至出现交联不完全现象;官能团比例相同时,交联密度较大的垫片,渗油量较小。     

脱醇型导热室温硫化硅橡胶复合材料的制备与性能

以工业副产品甲基三氯硅烷和八甲基环四硅氧烷为主要原料,合成了甲基三乙氧基硅烷和α,ω-二羟基聚二甲基硅氧烷,并以它们为原料制备了脱醇型导热室温硫化(RTV-1)硅橡胶,探讨了氧化锌/氧化镁、氧化铁/氧化镁及金属硅粉/氧化镁3种混合导热填料的种类和配比对RTV-1硅橡胶导热性、力学性能、绝缘性及热稳定性的影响。结果表明,当混合导热填料中的氧化镁质量分数为50%时,RTV-1硅橡胶复合材料的导热性从大到小依次为填充有金属硅粉/氧化镁、氧化锌/氧化镁和氧化铁/氧化镁者,此时用氧化锌/氧化镁和氧化铁/氧化镁2种混合导热填料填充的RTV-1硅橡胶也具有良好的力学性能;氧化锌与氧化镁和氧化铁与氧化镁2种混合导热填料在RTV-1硅橡胶中并用时具有协同导热作用;在混合导热填料中氧化镁的质量分数为50%时,氧化锌/氧化镁填充脱醇型导热RTV-1硅橡胶的导热性、拉伸性能、绝缘性和热稳定较好。     

球形氧化铝填充聚氨酯制备导热塑料

以聚氨酯为基材,球形氧化铝为导热填料,制备了填充型热固性塑料,研究了氧化铝填充量、表面处理对复合材料导热性能的影响,比较了不同粒径氧化铝填充的导热塑料的导热性能,并进行了两者复配研究。结果表明:聚氨酯复合材料的导热系数是导热通道的形成与界面层阻碍效应相互作用的结果;当氧化铝填充总量为600质量份且m(BAK–0100):m(BAK–0300)为1:2,并经过占总填料质量1.5%的KH560改性后,所得材料的导热系数高达2.51 W/(m·K)。     

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。