注塑成型熔接痕缺陷研究进展

根据国内外对熔接痕的各项研究,介绍了熔接痕的分类、形成过程、熔接痕的特点、数学模型及预测模型、影响熔接痕的各种因素等内容;并介绍了控制熔接痕的措施,对于全面了解熔接痕缺陷及研究进展将会有一定帮助.     

注塑件熔接痕位置预测技术的研究进展

介绍了注塑件充填过程熔接痕形成的数学模型,综述了数值模拟技术、数值模拟技术结合数学规划理论、阀式浇注塑大型注塑成型制品多浇口进料顺序控制技术等3种注塑件熔接痕位置预测、优化和控制方法,介绍了该技术的分析流程、预测方法及国内外的研究进展和应用实例,熔接痕控制技术,尤其是熔接痕消除技术的完善是今后熔接痕研究的一个重要方向。     

熔接痕位置预测及优化技术研究进展

综述了熔接痕位置预测、优化和控制技术的研究进展,介绍了填充过程熔接痕形成的数学模型。对数值模拟技术、数值模拟技术结合数学规划理论、阀式浇注和大型注射成型制品多浇口进料顺序控制技术等3种技术的分析流程、预测方法和应用实例进行了详细介绍,其中基于数值模拟技术和数学规划理论结合的熔接痕位置确定新算法是行之有效的熔接痕位置优化技术,已成为当前研究热点。随着该技术的日趋成熟,应用范围将逐渐增大。而阀式浇注和大型注射成型制品多浇口进料顺序控制技术的实施可以成功避免注塑件熔接痕的出现,在大型零件生产中具有广阔的应用前景。     

注塑件熔接痕强度预测及提高新技术

介绍了注塑件熔接痕强度预测及提高的几种新技术。综述了基于扩散理论和Flory—Huggins晶格理论的预测模型及基于BP神经网络的预测模型。给出了模型的适用范围。简述了热流道多浇口进料顺序控制、注射成型和模具设计等几种提高熔接痕强度、减少或避免熔接痕出现的新技术的作用机理及应用实例,指出进一步完善熔接痕强度预测模型和强度提高技术是今后熔接痕研究的一个重要方向。     

材料流变性能对注塑制品熔接痕的影响

介绍注塑制品熔接痕的分类及其形成,分析材料的流变性能对注塑制品熔接痕外观及性能的影响,着重阐述通过调整注塑工艺参数以改变材料的流变性能,从而改善熔接痕对注塑制品外观及性能的影响,并综合提出减小熔接痕损害的措施与方法。     

注塑制品熔接痕的自动识别

通过对注塑模充模过程中熔接痕形成机理的数学分析，给出了一个结合流动模拟数值实现过程的熔接痕自动识别算法，结合计算机图形学知识，利用计算机自动实现了注塑成型中熔接痕的起始、发展和形成。该算法可预测复杂制件的熔接痕位置，并适用于气体辅助注射成型和反应注射成型。最后通过一个算例验证了该算法的实用性。     

热流道顺序浇注成型移除熔接痕研究

为了有效移除注塑制品中的熔接痕,深入分析了熔接痕的形成过程和采用热流道顺序浇注成型移除熔接痕的机理,并使用模流分析软件Moldflow对顺序浇注成型移除熔接痕的过程进行了有限元模拟。模拟分析结果表明,随着阀浇口不同的开闭时机,顺序浇注成型可以有效地控制熔接痕的位置及长度,改善熔接区域的外观和性能,有效避免熔接痕的产生。实验表明,采用顺序浇注成型时制品的熔接痕已基本消除.     

基于CAE分析的PP—R管件熔接痕消除方法

针对PP－R管件生产中易产生熔接痕的问题，本文通过理论分析和计算，认为模具浇注系统设计不当是产生熔接痕的主要原因；进而应用CAE软件进行分析，通过调整浇口位置，对熔接痕的长度进行优化，使其减少到最小，结果得到实践验证。该方法为提高PP－R管件模具的质量提供了可靠的技术保证。     

隔热涂层对注塑制品熔接痕的改善机理研究

将隔热涂层与常规注塑工艺相结合,探究不同厚度涂层对玻纤增强注塑制品熔接痕的影响。研究结果表明:随着涂层厚度的增加,玻纤增强注塑制品熔接痕表面V型槽的深度不断减小,熔接痕处断面纤维取向逐渐趋于一致,界面缠结程度加深,熔接痕的拉伸性能不断增强。当涂层厚度为125μm时,相比于无涂层下成型的玻纤增强注塑制品,熔接痕的深度减少了77.9%,拉伸性能增加了80.9%,有效改善了玻纤增强注塑制品的熔接痕性能。     

应用Taguchi方法消除产品表面熔接痕的工艺研究

为提高注塑产品表面质量,消除产品表面熔接痕,本文利用Taguchi方法设计了L9实验矩阵,分析了熔体温度、模具温度、注射压力、保压时间等工艺因素对ABS制品表面熔接痕长度的影响,预测了最佳工艺参数,并在验证实验中消除了产品表面熔接痕,对注塑生产具有一定的指导意义。     

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.     

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.     

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。     

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.     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Some Large Wood-Boring Beetles in Southeastern USA

Ethanol and α-pinene were tested as attractants for large wood-boring pine beetles in Alabama, Florida, Georgia, North Carolina, and South Carolina in 2002–2004. Multiple-funnel traps baited with (−)-α-pinene (released at about 2 g/d at 25–28°C) were attractive to the following Cerambycidae: Acanthocinus nodosus, A. obsoletus, Arhopalus rusticus nubilus, Asemum striatum, Monochamus titillator, Prionus pocularis, Xylotrechus integer, and X. sagittatus sagittatus. Buprestis lineata (Buprestidae), Alaus myops (Elateridae), and Hylobius pales and Pachylobius picivorus (Curculionidae) were also attracted to traps baited with (−)-α-pinene. In many locations, ethanol synergized attraction of the cerambycids Acanthocinus nodosus, A. obsoletus, Arhopalus r. nubilus, Monochamus titillator, and Xylotrechus s. sagittatus (but not Asemum striatum, Prionus pocularis, or Xylotrechus integer) to traps baited with (−)-α-pinene. Similarly, attraction of Alaus myops, Hylobius pales, and Pachylobius picivorus (but not Buprestis lineata) to traps baited with (−)-α-pinene was synergized by ethanol. These results provide support for the use of traps baited with ethanol and (−)-α-pinene to detect and monitor common large wood-boring beetles from the southeastern region of the USA at ports-of-entry in other countries, as well as forested areas in the USA.