小粒径玻璃微珠共混改性LLDPE的研究

研究小粒径玻璃微珠的粒径和用量时线形低密度聚乙烯(LLDPE)性能的影响。结果表明,添加不同粒径的玻璃微珠可使LLDPE的力学性能显著提高,耐热性能也有一定改善,粒径为3μm的玻璃微珠改性效果最好。随着玻璃微珠用量的增加,LLDPE的拉伸强度和冲击强度提高,但拉伸弹性模量和断裂伸长率基本不变。玻璃微珠粒径时LLDPE性能的影响大于用量的影响。     

空心玻璃微珠增韧高密度聚乙烯的性能研究

采用玻璃微珠（GB）对高密度聚乙烯（HDPE）进行增韧改性。通过扫描电子显微镜、偏光显微镜和力学性能测试考察了偶联剂处理、基体韧性、玻璃微珠粒子用量、粒径大小和结晶等因素对HDPE/GB体系微观形态和性能的影响。结果表明,偶联剂可以明显改善空心玻璃微珠在基体中的分散,对于HDPE/GB体系,要求基体的最低冲击强度为5.0～5.5KJ/m2。玻璃微珠用量25%,粒径2.5μm时,冲击强度可达38.0kJ/m2。     

玻璃微珠改性含油铸型尼龙力学性能研究

研究了玻璃微珠改性含油铸型尼龙复合材料的力学性能。结果表明,玻璃微珠使复合材料的冲击强度有所降低;拉伸强度、拉伸弹性模量、弯曲强度和弯曲弹性模量均得到提高,在玻璃微珠的质量分数为15％—20％时提高幅度较大;复合材料的硬度也有所提高。     

BMI树脂基轻质耐压复合材料的制备及性能研究

采用空心玻璃微珠填充改性双马来酰亚胺(BMI)树脂,研究了玻璃微珠用量和粒径以及表面处理的玻璃微珠,对材料压缩性能以及吸水性的影响。结果表明小粒径(10μm)较大粒径(70μm)玻璃微珠填充改性双马来酰亚胺树脂的压缩强度降低缓慢,经表面处理后可获得最佳效果。少量地加入玻璃微珠可降低环氧树脂的吸水性,但随着玻璃微珠含量的增大,体系的吸水性会随之增加。当玻璃微珠含量为30%时,复合材料密度降至0.74gcm3,压缩强度仍可以达到68.5MPa。     

玻璃微珠填充PP复合材料力学性能与熔融结晶的研究

研究了玻璃微珠填充聚丙烯(PP)中玻璃微珠含量及粒径大小对复合材料力学性能和熔融、结晶行为的影响。结果表明:填充体系随着玻璃微珠含量增加,拉伸强度增加,冲击强度降低。在相同条件下,小粒径微珠填充体系拉伸强度和冲击强度均高于大粒径微珠填充体系。玻璃微珠在PP中具有成核作用,PP以异相成核方式结晶,提高了PP的结晶温度,结晶速率增大,流动性先增加后降低。     

空心玻璃微珠填充改性双马来酰胺树脂复合材料耐热性能的研究

采用空心玻璃微珠填充改性双马来酰胺树脂（BMI），研究了玻璃微珠用量，粒径及表面处理对材料性能的影响，并用热机械分析仪（TMA）测定了材料的线膨胀系数。结果表明随着玻璃微珠质量份数的增加马丁耐热温度提高，线膨胀系数呈降低的趋势，小粒径（10μm）和经过表面处理的玻璃微珠对马丁耐热温度改性的效果更加显著。     

空心玻璃微珠填充改性双马来酰胺树脂复合材料耐热性能的研究

采用空心玻璃微珠填充改性双马来酰胺树脂（BMI），研究了玻璃微珠用量，粒径及表面处理对材料性能的影响，并用热机械分析仪（TMA）测定了材料的线膨胀系数。结果表明随着玻璃微珠质量份数的增加马丁耐热温度提高，线膨胀系数呈降低的趋势，小粒径（10μm）和经过表面处理的玻璃微珠对马丁耐热温度改性的效果更加显著。     

GB/HDPE复合材料拉伸性能及介电性能研究

采用小粒径玻璃微珠（GB）与HDPE熔融共混，研究了玻璃微珠用量及表面处理对复合材料拉伸性能及介电性能的影响。研究结果表明，无论玻璃微珠表面处理与否，GB／HDPE复合材料的拉伸强度和拉伸弹性模量均随着玻璃微珠用量的增加而增大；经过偶联剂KH550和EB151处理的玻璃微珠与HDPE复合后，拉伸强度和拉伸弹性模量有一定的提高。复合材料的介电常数随玻璃微珠用量增加呈现增大的趋势，经过改性的复合材料的介电常数比未经改性的有所增加，而玻璃微珠的添加和界面改性对介电损耗的影响不大。     

玻璃微珠填充PP复合材料力学性能与熔融结晶的研究

研究了玻璃微珠填充PP中玻璃微珠含量及粒径大小对复合材料力学性能和熔融、结晶行为的影响.结果表明,复合材料随着玻璃微珠含量增加,拉伸强度增大,冲击强度减小.在相同条件下,小粒径微珠填充体系拉伸强度和冲击强度均高于大粒径微珠填充体系.玻璃微珠在PP中具有成核作用,PP以异相成核方式结晶,提高了PP的结晶温度,结晶速率增大.流动性随着玻璃微珠含量的增加而增大,然后随之下降.     

HGB表面改性及粒径分布对ABS/HGB性能影响

研究空心玻璃微珠(HGB)的表面改性和粒径分布对丙烯腈-丁二烯-苯乙烯共聚物(ABS)/HGB复合材料力学性能的影响.结果表明:HGB的表面改性可以提高ABS/HGB复合材料的拉伸、弯曲和冲击强度;硅烷偶联剂KH550的改性效果优于KH560的;粒径分布窄的HGB填充ABS复合材料具有较高的拉伸、弯曲和冲击强度.     

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.     

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.     

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.     

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.