针状纳米级碳酸钙的工业生产与应用

经小试、中试（70 t/a装置）、工业化试验（25 kt/a工业装置）,在自研的多组分结晶导向剂的作用下,较高温度（35～75℃）、较高浓度（7%～12%）碳化工艺条件下合成粒度分布均匀,粒径为10～20 nm,长径比为15～20,比表面积≥90 m2/g,总孔容≥0.26 cm3/g的针状（晶须）纳米碳酸钙。经在乳胶漆、PVC制品中试用,均取得理想效果。文中还给出了10 kt/a针状（晶须）纳米级碳酸钙新建与改建设计方案。     

纳米碳酸钙的皂化程度对硅酮密封胶性能的影响

将皂化程度不同的纳米碳酸钙填充于硅酮密封胶中,考察皂化程度分别为0～15%时,纳米碳酸钙对硅酮密封胶性能的影响,探索改性纳米碳酸钙在硅酮密封胶中的作用机制。结果表明,比表面积为23.35m~2·g~(-1)、皂化程度为15%的纳米碳酸钙,其成品胶的黏度从58.7Pa·s逐渐下降至52.4Pa·s,挤出速率从18.8g·(20s~(-1))上升至24.78g·(20s~(-1))。随着皂化程度增加,填充后的成品胶,其邵氏硬度和拉伸强度呈减小的趋势,表干时间稍有延长,成品胶的力学强度呈先下降后略有回升的趋势。比表面积为17.71 m~2·g~(-1)、皂化程度为5%～10%的纳米碳酸钙,其成品胶的强度保持率达到95%以上,比表面积为23.35 m~2·g~(-1)的纳米碳酸钙达到了101.7%。比表面积分别为17.71 m~2·g~(-1)和23.35 m~2·g~(-1)的碳酸钙,当皂化程度为5%～10%时,经高温处理及湿热处理后,成品胶的强度保持率分别维持在98%及75%以上。     

中国纳米级碳酸钙工业化生产技术新进展

纳米级碳酸钙属于轻质碳酸钙，其平均粒径≤100nm。国内外已实现工业化有4种技术：间歇鼓泡式、连续喷雾式、间歇搅拌式和超重力式等。进行小试或中试有喷射式、喷杯式、超声空化式、高剪切式、内循环式、管道式、管线乳化式、列管式和复合式等9种碳化工艺。其共同特点为低温低浓下生产纳米碳酸钙，能耗高，设备投资大，生产能力低等。河北科技大学在总结现有生产工艺的基础上，提出高温高浓非冷冻式碳化工艺，经小试、70吨／年中试、2．5万吨／年工业装置工业化试验，在自行开发的多组分结晶导向剂的作用下，高温（35～75℃）高浓（7％～12％）工艺条件下，合成粒径分布均匀．平均直径为10～20nm、长径比为15～20、比表面积≥90mVg、总孔容≥0．26mL／g的针状（晶须）纳米碳酸钙。为工业化生产纳米级碳酸钙又开辟出一条新路子，其产品及综合技术处于国际领先水平。     

聚丙烯/无机粉体/异形纤维复合材料的制备

以聚丙烯为聚合物基体,以纳米碳酸钙为无机组分,采用聚对苯二甲酸乙二醇酯(PET)纤维,纤维截面形状分别为圆形、扁平形和三角形,通过熔融共混的方法制备了聚丙烯/纳米碳酸钙/异形纤维复合材料,并采用不同的改性剂对纳米碳酸钙进行表面改性,通过扫描电子显微镜观察了纳米碳酸钙的分散情况,重点分析了聚丙烯/纳米碳酸钙/异形纤维复合材料的结构与性能的关系。结果表明,硅烷偶联剂对碳酸钙表面有机化处理的效果好于硬脂酸;纤维截面形状不同对复合材料的增强效果也不同,其中比表面积最大的三角形纤维增强效果最佳;当纳米碳酸钙的含量为3%(质量分数,下同)(2%硅烷偶联剂处理)、三角形PET纤维的长径比为80、含量为2%(体积分数,下同)(4%硅烷偶联剂处理)时,制得的聚丙烯/纳米碳酸钙/异形纤维复合材料的屈服强度比纯聚丙烯提高近21%,弹性模量提高了约82%。     

针状氢氧化镁的研制及其结晶性能研究

本文介绍了以苦卤和石灰孔等为原料,制备针状氢氧化镁的工艺过程。针状结晶的长度10—100μ,直径0.2—0.5μ,长径比>50,晶体在〈101〉方向的微观内应变<3×10~(-3),比表面积(BET)<20m~2/g。     

针状氢氧化镁在热塑性塑料中的增强与阻燃研究

针状氢氧化镁,其针状结晶的长度10～100μm,直径0.2～0.5μm,长径比>50,在<101>方向的微观内应变<3×10~(-3),比表面积(BET)<20m~2/g,在与聚氯乙烯,聚丙烯等的填充时,具有优良的阻燃作用,同时,所填充合成材料的机械性能显著增强。     

消化用水的温度对纳米碳酸钙产品性能的影响

采用碳化法制备了纳米碳酸钙,考察了消化时的水温对石灰乳产率、制备的纳米碳酸钙产品的粒径分布、比表面积、吸油值和白度等物理性能的影响。结果表明：石灰经高温消化,能够提高石灰乳的产率,产率可达92%;高温消化有利于碳酸钙比表面积的升高、同时降低碳酸钙的颗粒粒度及吸油值,对碳酸钙的白度影响较小。当消化用水的温度为60℃时,制备的碳酸钙比表面积较高,而其粒度和吸油值较低。     

纳米碳酸钙粒径测试的研究

纳米碳酸钙的粒径是决定其性能的重要参数之一。通过电子显微镜法、X射线衍射法、氮气吸附BET法,压汞法和激光散射法,对纳米碳酸钙的颗粒大小做了表征。结果表明:扫描电子显微镜法、X射线衍射法和氮气吸附BET法可用于测定纳米碳酸钙的一次粒径,其结果准确;激光散射法可有效表征纳米碳酸钙的二次粒径;表面处理剂用量对纳米碳酸钙BET比表面积测试结果有一定影响;压汞法测试纳米碳酸钙比表面积,结果误差较大。     

改性纳米CaCO3/DOP体系流变性能研究

硬脂酸改性纳米碳酸钙分散于DOP中形成的分散体系,具有宾汉流体的流变性能,考察了不同比表面积的改性纳米碳酸钙以及改性剂硬脂酸的不同用量对CaCO3/DOP体系的流变性能的影响,结果表面更高比表面积的纳米钙以及合适的硬脂酸用量分散于DOP中具有更高的屈服值。     

纳米碳酸钙形态对书刊热熔胶力学性能的影响

以乙烯-醋酸乙烯酯共聚物(EVA)为基材、改性松香树脂为增黏剂、纳米碳酸钙为改性剂,制备了一种EVA型书刊热熔胶,研究了纳米碳酸钙的形态对该书刊胶性能的影响。结果表明:纳米碳酸钙的形态对书刊胶性能有较大影响,其中,立方型纳米碳酸钙对书刊胶黏度的提升幅度较小,链状纳米碳酸钙则可明显提高书刊胶的黏度,而针状纳米碳酸钙对书刊胶剥离强度的贡献较大。将立方纳米碳酸钙与针状纳米碳酸钙按1:1的比例并用,不仅可有效改善书刊胶的沉降性能,还可提高书刊胶的黏结防剥离特性。     

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.