宽峰聚乙烯／蒙脱土纳米复合材料的制备

利用2种不同的方法制备了2种氢调敏感性不同的蒙脱土／氯化镁／四氯化钛（MMT／MgCl2／TiCl4）催化剂,利用这2种催化剂及其混配催化剂,通过原位聚合法,制备出一系列宽峰聚乙烯纳米复合材料,采用X_射线衍射仪（XRD）、凝胶色谱测试分析（GPC）及力学性能测试等方法对催化剂及聚合产物进行分析,结果表明,2种催化剂以及按照不同比例混合的混配催化剂均表现出较高的聚合活性,XRD测试结果表明,蒙脱土片层在乙烯聚合过程中发生了插层及剥离,以单片层或几层共存的形式分散于聚乙烯基质中;用混配催化剂可制得宽峰聚乙烯纳米复合材料,Mw／Mn=7．23,并且聚合物的堆积密度达到工业生产的标准,宽峰聚乙烯纳米复合材料的综合力学性能较工业产品5000S及工业上应用的管材料有很大的提高。     

利用混配催化剂制备宽峰聚乙烯／蒙脱土纳米复合材料的方法

利用混配催化剂制备宽峰聚乙烯／蒙脱土纳米复合材料的方法。将催化剂A和催化剂B按照1：9—9：1的比例制备混配催化剂，利用混配催化剂制备宽峰聚乙烯／蒙脱土纳米复合材料。该纳米复合材料的聚合产物堆积密度大于0．37g／cm^3，拉伸强度大于35MPa，维卡耐热温度大于130℃，分子量分布S值在8～16。本发明提供的混配催化剂适用于淤浆聚合工艺制备宽峰聚乙烯／蒙脱土纳米复合材料。该纳米复合材料具有良好的力学强度、耐热性及加工性能，使其可在薄膜、建材、管道、吹塑成型用料、注射成型用料、电线电缆等领域有广泛的用途。     

聚乙烯/蒙脱土纳米复合材料的制备及性能研究

以蒙脱土／十六烷基三甲基溴化铵作为前驱物负载Ziegler-Natta催化剂，通过插层原位聚合的方法制备了聚乙烯／蒙脱土纳米复合材料。对聚乙烯／蒙脱土纳米复合材料的制备规律进行了研究。用透射电镜、扫描电镜、XRD，DSC等手段研究了结构和性能的相互关系，以及蒙脱土的含量对复合材料熔点与结晶行为的影响。研究表明：蒙脱土的片层结构被破坏，并以纳米级均匀分散在聚合物基体中。蒙脱土的质量分数为3％左右时，聚乙烯／蒙脱土纳米复合材料具有优良的综合性能。     

有机插层剂对聚酰胺6／MMT纳米复合材料制备的影响研究

以烷基胺、季铵盐和氨基酸作为有机插层剂与蒙脱土片层进行阳离子交换，制备出层间距不同的有机蒙脱土。采用熔融插层法和原位聚合法分别制备聚酰胺（R％）／蒙脱土（MMT）纳米复合材料，并利用XRD、FT-IR、TEM对有机蒙脱土及纳米复合材料进行结构表征。研究结果表明：用烷基胺、季铵盐和氨基酸有机插层剂改性的蒙脱土层间距由原来的1．25nm分别增大到3．21nm、3．99nm和1．82m；季铵盐有机插层剂更适用于熔融插层法制备PA6／MMT纳米复合材料，而氨基酸有机插层剂更适用于原位聚合法制备PA6／MMT纳米复合材料。     

宽峰高相对分子质量高密度聚乙烯专用料的研制

通过淤浆法小试聚合装置合成了不同相对分子质量的高密度聚乙烯粉末,对聚合工艺条件对产物物性的影响进行了研究。同时,考察了不同相对分子质量的聚乙烯共混合成宽峰聚乙烯专用料的规律。结果表明:通过调整聚合工艺条件,在淤浆法小试聚合装置聚合产物的相对分子质量可调;不同相对分子质量的聚乙烯粉末共混可以制备宽峰HDPE;合成的宽峰HDPE专用料的综合力学性能优良,在树脂研究院进行加工,性能良好。     

宽峰高相对分子质量高密度聚乙烯专用料的研制

通过淤浆法小试聚合装置合成了不同相对分子质量的高密度聚乙烯粉末,对聚合工艺条件对产物物性的影响进行了研究.同时.考察了不同相对分子质量的聚乙烯共混合成宽峰聚乙烯专用料的规律.结果表明:通过调整聚合工艺条件.在淤浆法小试聚合装置聚合产物的相对分子质量可调;不同相对分子质量的聚乙烯粉末共混可以制备宽峰HDPE:合成的宽峰HDPE专用料的综合力学性能优良,在树脂研究院进行加工,性能良好.     

环氧树脂／蒙脱土纳米复合材料的制备与剥离机理研究进展

阐述了蒙脱土的性质及其在基体树脂中的剥离机理、环氧树脂／蒙脱土纳米复合材料的制备方法。原位插层复合法是制备环氧树脂／蒙脱土纳米复合材料最常用的方法；有机改性剂、固化剂及固化条件会对蒙脱土在环氧树脂中的剥离与插层行为产生影响；环氧单体聚合过程中产生的弹性力是使蒙脱土片层发生剥离的主要原因。重点介绍了近几年来制备高度剥离型纳米复合材料的方法和工艺，指出蒙脱土在复合材料中的完全均匀剥离仍然是现阶段有待解决的关键问题。     

聚乙烯/凹凸棒石纳米复合材料的研究

采用原位聚合法制备聚乙烯／凹凸棒石纳米复合材料,结果表明：凹凸棒石的纳米级晶须可在聚乙烯树脂中能够较好地分散,聚乙烯在凹凸棒石表面绞缠,并且在不同晶须间绞缠,形成独特的交联网状结构一“有机／无机凝胶”;纳米复合材料能够显著提高聚乙烯的抗冲强度。     

蒙脱土/橡胶纳米复合材料的研究进展

概述了蒙脱土／橡胶纳米复合材料的结构、制备方法及性能，并展望了其应用前景。根据蒙脱土片层的分散情况可将蒙脱土/橡胶纳米复合材料分为普通型、插层型和剥离型；复合材料的制备方法包括单体插层原位聚合法、橡胶溶液插层法、液体橡胶插层法、橡胶乳酸插层法、橡胶熔体插层法及小分子与大分子的结合插层法；复合材料具有良好的加工性能、优异的力学性能及阻隔性能等，广泛用于轮胎内胎、气密层、胶带、胶鞋等制品。     

聚合物/有机蒙脱土纳米复合材料分散形态的制备影响因素

选择不同种类的有机蒙脱土（OMMT）和不同聚合物种类,采用不同加工条件和工艺,利用机械混炼法或挤出法制备出了不同亚微观形态的聚合物/有机蒙脱土纳米复合材料。首先通过研究具有不同的改性层间距的OMMT,发现改性后层间距的增大有利于聚合物分子的插层及蒙脱土片层的剥离,有利于制备剥离型纳米复合材料,并用示意图简要说明了形成过程;而同一种OMMT在具有不同分子结构的聚合物中,利用实例（高密度、低密度、线型低密度聚乙烯）以及简易示意图说明了聚合物分子链结构对于制备的纳米复合材料的亚微观形态的影响机理。在加工工艺条件中,加工过程中的剪切力大小是主要影响因素,通过以挤出法和机械混炼法制备的PP/OMMT与EPDM/OMMT纳米复合材料的TEM结果对比分析,说明剪切力的增大有利于蒙脱土片层的分离,更倾向于制备出剥离型纳米复合材料。     

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.     

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.     

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。