双色注射成型技术研究进展

介绍了双色注射成型工艺原理及特点,并着重探讨了双色注塑成型前沿技术及发展现状。最后对双色注塑成型技术的发展前景进行了分析预测。指出双色注塑应与其它注塑技术结合,向多色、多材质注塑成型方向发展。精简加工操作程序、降低双色产品的制作成本、优化双色注塑模具等将成为未来研究者的最主要任务。     

双色注塑成型技术及其发展

双色注塑成型技术是近几年发展起来的一种新兴塑料注塑成型方法。综述了目前采用的四种双色注塑成型工艺,探讨了其成型工艺特点,介绍了双色注射塑料制品及模具的设计要点,并展望了该项技术的发展前景。     

高光注塑成型模具热响应研究

高光无痕注射成型技术是一种新兴的注射技术,能够消除塑件表面熔接痕等缺陷,表面可以达到镜面效果,免去二次喷涂。本文通过建立模具的二维几何模型,利用ANSYS模拟了加热、冷却过程,获得了模具表面及熔体中心层的热响应和温度分布情况。同时对比分析了常规注塑与高光注塑成型两种成型工艺,通过加热、冷却时间及温度分布等结果的对比,验证了高光注塑的优越性。     

高光无痕注塑成型模具热响应的研究

高光无痕注射成型技术是一种新开发的注射技术,能够消除塑件表面熔接痕等缺陷,表面可以达到镜面效果,免去二次喷涂。通过建立模具的二维几何模型,应用ANSYS模拟了加热、冷却过程,获得了模具表面及熔体中心层的热响应和温度分布情况;对比分析了常规注塑与高光无痕注塑两种成型工艺;通过加热、冷却时间及温度分布等对比,验证了高光无痕注塑的优越性。     

双色高光成型塑件的结构设计技术

根据双色注塑和高光注塑成型对塑件结构的双重要求,基于和普通塑件结构设计方法的对比,针对双色高光塑件的整体结构、连接方式、防溢设计及凸起、加强筋、圆角、孔等进行研究.结合双色高光塑件的双层结构及表面高光的突出特点,得出其结构设计需遵守结构协调、黏结牢固及壁厚均匀三项原则.并以某液晶电视机前壳和电器外壳结构设计为例,对双色高光塑料制品的结构设计做了具体阐述.     

玩具手柄双色注塑模具设计

分析了双色玩具手柄的结构,基于双色注射成型技术,完成了玩具手柄的成型零件、热流道浇注系统和弹块式定模抽芯机构的设计。结果表明:该双色注塑模具和成型零件设计合理,抽芯运动有序,有效地解决了双色塑件注射成型时出现的料口堵塞、2次划痕等质量问题。     

人机工程学鼠标底壳双色注塑模具设计

通过具有人机工程学复杂曲面造型的双色鼠标底壳零件,介绍了双色注塑零件可注塑性工艺分析方法,利用UG6.0对双色注塑的鼠标底壳模具进行了结构设计,比较详细地论述了在复杂曲面和双色成型双重特点下模具设计的考虑因素,着重介绍了双色模具内外抽芯机构设计过程和热塑性弹性体TPE外层包覆粘合的双色模具设计特点和成型方法。试模结果表明,该模具设计合理,制造方便,实现全自动双色注塑成型操作,成型过程能力指数Cpk大于1.33, 成型周期仅43 s,完全满足了鼠标底壳高品质和高效率的注射成型要求。     

高光注射成型技术在超薄塑料件中的应用研究

运用Moldflow软件对超薄花盆塑料件的普通注射成型及高光注射成型进行模拟分析。结果表明,采用高光注射成型超薄塑料件解决了普通注射成型难以解决的短射问题,避免了普通注射成型需依赖高注塑压力的现象,且缩短了熔接痕的长度,改善了塑料件的表观质量。     

高光注塑成型产品质量的评价体系

介绍了高光注塑成型技术原理,构建了高光注塑成型产品必须满足的传统注塑成型产品质量的评价体系,并着重介绍了表面光泽度、熔接线、表面浮纤和表面硬度等高光注塑成型产品的主要评价项目。     

双色注塑技术在家电模具制造中的应用分析

正双色注塑是一种可以一次成型生产出表面高光泽并具有内外两层不同颜色搭配塑件的技术,该技术的应用可以大大提高整机产品的外观效果。与普通模具和目前已经广泛应用的小型双色/双组份注塑相比,大型双色注塑模具在产品特点、模具结构、动作顺序、浇口设置、流道布局等方面都有很大差异,难度大大增加。在连续生产时,外层注射和内层注射同时进行,因此     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.