改进工艺制备PVC-O管材料特性试验分析

分析了硬聚氯乙烯(PVC-U)管材自身的优劣势,引出基于双轴取向拉伸工艺的技术改进方法。通过对双轴取向聚氯乙烯管(PVC-O)现状分析,提出PVC-O管量产化的改进工艺成型方法,并完成了PVC-O管的制备。对成品管与未改进的PVC-U管进行了三组对比关联试验,通过环刚度、环柔度试验,观察两种PVC制品的裂纹微观结构,得到两种管材的制品指标和特性,三组试验均证实了PVC-O管优于传统PVC-U管材,且改进工艺提升了PVC管材产品的质量,这为PVC-O管生产与应用提供科学依据。     

宝硕高抗冲绿色无铅饮水用PVC-M管材面市

本刊讯12月10日,河北宝硕管材有限公司在北京大方饭店举办新产品发布会,首次推出宝硕自主研发的新产品“高抗冲绿色无铅饮水用管材”。在同行业率先实现了产品升级,并填补了国内新型PVC管材的一项空白。会上,宝硕公司技术人员介绍道:PVC-M管材具有使用安全、施工便利、经济合理等特点,它采用氯化聚乙烯改性的PVC为原料,在不降低管材强度的条件下,极大地改善材料的韧性。PVC-M管材是宝硕公司结合宝硕公司几十年PVC管道研究开发与应用经验,借鉴国外的先进标准和技术,研发成功的一种具有优异的韧性和抗冲击性的管材。PVC-M管材在原料上采用非铅缘体系无铅生产配方和生产工艺,排除了重金属的危害,是绿色环保产品,独特的配方体系,使PVC-M管材集PE管材的韧性和PVC-U管材的高强度于一身,不仅克服了PVC-U管材脆性大、易破损的不足,同时解决了PE管材在安装与维修时工序繁琐、对环境要求苛刻的问题,施工速度快,易于检测,管道接口可靠性高,而且工程造价低。与PE管材相比,PVC-M管材的生产成本约低20%,具有很强的竞争力。是一种安全性更高的塑料管道。据悉,PVC-M管道在国外已有十几年的使用经验,如英国、澳大利亚、南非等国家...     

几种常见给水PVC工程管道的对比分析

从混配料技术要求、允许内压及抗外压能力、设备要求、性能指标要求及接口形式5个方面分别介绍并对比了硬聚氯乙烯（PVC-U）给水管、高性能硬聚氯乙烯（PVC-UH）给水管、抗冲改性聚氯乙烯（PVC-M）给水管及双轴取向聚氯乙烯（PVC-O）给水管4种硬质聚氯乙烯管材,并重点总结了PVC?UH管道的选取优势和应用案例,最后针对PVC?UH管道的施工给出了实践性建议。     

加快创新开发,开拓聚氯乙烯压力管道系统的新局面

近年来聚氯乙烯管道取得了重大进步。PVC-M管材(改性聚氯乙烯管材)、PVC-O管材(取向聚氯乙烯管材)兼有非凡的强度和韧度,和传统的硬聚氯乙烯管材比可以采用较高的设计应力,显著地节约材料。     

双轴取向聚氯乙烯（PVC-O）管道的发展研究分析

结合国内外管材原料、技术和市场的需要,简述了PVC管材现有状况及发展方向.双轴取向拉伸管材作为一种新型先进技术,在提高管材性能的同时节约材料,具有非常好的竞争地位.文中研究分析了PVC-O管材生产技术、优越性能及良好的社会效益和经济效益.     

高抗冲聚氯乙烯管材的研究与开发

研究了聚氯乙烯(PVC)树脂、抗冲改性剂、复合润滑剂及工艺对高抗冲聚氯乙烯(PVC-M)管材影响。结果表明:PVC树脂相对分子质量适中,粒度均匀适合PVC-M管材生产;甲基丙烯酸甲酯/丁烯/苯乙烯三元共聚物(MBS)抗冲改性效果优于氯化聚乙烯(CPE)的,用量为8份时,材料由脆性向韧性转变;复合润滑剂用量多,力学性能较差,PVC-M管材配方中复合润滑剂用量不宜超过2.5份。     

布管法生产PVC-O管材的理论计算与实验

针对一种新型PVC-O管材生产方法,从理论上计算扩胀过程管壁内的应力分布,并研究扩胀PVC管坯的最佳工艺参数.讨论两种不同扩胀比下管材与未扩胀管坯的强度变化.按照弹性理论计算,扩胀时管壁内的应力近似为线性分布,其中环向应力近似为均匀分布.扩胀后的PVC-O管材强度和弹性模量都有明显提高,但断裂伸长率降低;且变化的幅度随着扩胀比的提高而增大.通过对PVC管坯扩胀参数的优化,可以获得外观优良,强度提高明显的PVC-O管材.     

影响PVC-M管材料性能的主要因素

主要研究了不同聚氯乙烯(PVC)树脂、稳定剂、增韧剂及有机增强剂等对改性PVC(PVC-M)管材料刚性和韧性的影响。结果表明,有机增强剂可以弥补由增韧剂造成的管材刚性下降。     

PVC-O管材生产加工及其特性评价

PVC-O管材是在PVC材料的玻璃化转变温度上通过双向拉伸对材料的分子进行重新排列,使材料(管壁)形成网状结构,能够承受发源于材料机体微细裂纹或管壁表面划痕的脆性破坏,使管材的强度、韧性和抗开裂性能得到显著提升。双轴取向聚氯乙烯(PVC-O)管材是通过特殊的取向加工工艺制造的管材,这一加工工艺是把采用挤出方法生产的PVC-U管材进行轴向拉伸和径向拉伸,使管材中的PVC长链分子在双轴向规整排列,获得高强度、高韧性、高抗冲、抗疲劳的新型PVC管材,性能远优于普通PVC-U管材。开发PVC-O管材,可以大大节约原材料资源,降低成本,提高产品性能,具有明显的经济效益和社会效益。     

PVC-M管材的技术现状和发展趋势

从技术研究现状、市场应用情况和未来发展趋势等方面对PVC-M管材进行了综述,以期为PVC-M管材的生产开发提供参考。     

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.     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。