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采用熔融共混法制备了多种粒径、不同含量的石墨烯(GNP)/聚丙烯(PP)纳米复合材料,通过流变实验和拉伸实验分别研究了GNP粒径和GNP含量对复合材料流变特性的影响以及注塑成型工艺参数(注塑温度、注射压力、注射速度及背压)对复合材料拉伸性能的影响。研究结果表明,GNP微粒能够显著改善PP基体的抗拉强度,在一定含量范围(3%~9%)和较大粒径(40μm)时,会对PP熔体的流动性产生较大影响。虽然,注塑成型工艺参数对GNP/PP复合材料的抗拉强度影响较小,但是,其对材料的韧性影响较大。随着注塑的温度、压力、速度和背压的升高,材料韧性呈先增后降的趋势,最优参数组合为注塑温度215℃、注射压力60 MPa、注射速度50%、背压压力1 MPa。 相似文献
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以高温聚酰胺10T(PA10T)为基体,制备碳纤维增强聚酰胺10T复合材料(PA10T/CF),研究复合材料注射成型的工艺参数对复合材料力学性能的影响。通过对复合材料的纤维保留长度进行分析,得到最佳平均保留长度为295μm,同时得到优化的注塑工艺参数为注塑温度330℃,注塑压力50%(注射压力最大值的50%),注射速率70%(注射速率最大值的70%),保压压力50 MPa,模具温度30℃。分析扫描电子显微镜(SEM)表征结果可知,不同纤维含量的PA10T/CF复合材料采用优化工艺参数成型时,其样品断面呈韧性断裂且CF均匀良好地分散。 相似文献
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基于传热学和塑料加工流变学理论,建立熔体在模具型腔中流动的数学模型,对聚丙烯(PP)250 mL输液瓶瓶坯注塑工艺参数对注塑成型性能的影响规律进行了研究。根据正交试验原理,建立由熔体温度、保压压力、模具温度和保压时间等工艺参数共同作用的正交试验,利用Moldflow软件对输液瓶瓶坯的成型过程进行流动模拟,并通过极差分析法和方差分析法获得了最优工艺参数组合。并在此条件下进行试模检验,得到的瓶坯品质合格,尺寸满足公差要求。 相似文献
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利用韧性优良的共聚聚丙烯(PPR)作为增强基体,通过玻纤(GF)与PPR制备高性能PPR/GF复合材料,研究了流动改性剂、马来酸酐接枝聚丙烯(PP-g-MAH)和玻纤的含量以及挤出次数对PPR/GF复合材料结构与性能的影响.结果表明:自制的流动改性剂可大幅增加PPR/GF的熔体质量流动速率,流动性可适用于注塑工艺;PP-g-MAH增加了PPR基体与GF之间的界面相互作用,提高PP/GF复合材料的力学性能;随玻纤含量增加,PP/GF复合材料的拉伸强度和模量大幅增加,缺口冲击强度和断裂伸长率有所降低,但材料的韧性仍保持较高水平,所制备PPR/GF/PP-g-MAH共混材料的性能与ABS相当,可替代ABS工程塑料作为结构件使用;多次挤出加工会降低PPR/GF复合材料中玻纤的平均长度和材料的力学性能. 相似文献
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通过实验研究聚对苯二甲酸丁二醇复合材料水辅注塑的成型工艺。实验根据水注入制品对长度的影响测得了各种工艺参数以及它们的机械性能。最后,作了水辅助和气体辅助注塑件的比较。实验发现熔体压力,熔融温度,及短射类型是影响水注塑行为的决定性参数。 相似文献
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《化学与生物工程》2016,(9)
采用熔融共混/注塑成型法制备了一种新型的用于制备含铜宫内节育器的聚合物合金基含铜复合材料,即铜/聚氧化乙烯/低密度聚乙烯(Cu/PEO/LDPE)复合材料。采用正交实验研究了加热温度、注射温度、注射压力、注射速率、保压压力和保压时间等对该复合材料Cu2+释放速率的影响。结果表明:注射压力对复合材料Cu2+释放速率的影响最大,其它工艺参数的影响相对较小,且影响大小的顺序依次为:注射压力保压时间注射温度注射速率加热温度保压压力,调控注塑工艺参数是调控该复合材料Cu2+释放行为的手段之一。获得了制备宫内节育器Cu/PEO/LDPE复合材料的最佳注塑工艺参数为:注射压力60bar、注射温度165℃、加热温度180℃、保压压力10bar、保压时间0.5s、注射速率70%。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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. 相似文献
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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. 相似文献
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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. 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
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. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
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。 相似文献