硬段含量对脂肪族阴离子水性聚氨酯性能的影响

以异佛尔酮二异氰酸酯和聚酯多元醇为主要原料,用预聚混合法合成了一系列硬段含量不同的脂肪族阴离子水性聚氨酯纳米乳液。通过FTIR、GPC、DSC等,研究了硬段含量对产品结构和性能的影响。结果表明,随着硬段含量增加,乳液平均粒径逐渐增大但仍小于100nm,粒径分布逐渐变宽;分子结构中成氢键的脲键增多;数均相对分子量略有增加;DSC分析表明软段玻璃化温度向低温漂移,而硬段玻璃化温度向高温漂移,说明两相微相分离程度增加。硬段含量为30%时胶膜拉伸强度最高达52MPa,而断裂伸长率随硬段含量增加从2250%急剧减小到863%。耐水性在硬段含量最高时最佳。     

可再生多元醇蓖麻油基聚氨酯灌封胶的制备与性能研究

以蓖麻油、聚醚多元醇(PPG)、液化MDI为主要原料,以1,2-丙二醇(PDO)为扩链剂,采用预聚体法合成制备出聚氨酯灌封胶,讨论了异氰酸酯指数R、硬段质量分数等对聚氨酯灌封胶性能的影响。结果表明:随硬段质量分数、R值的增加,材料的硬度、拉伸强度上升,而断裂伸长率降低;聚氨酯耐水解性(吸水率≤0.366%)好,起始分解温度(277℃)高,热稳定性好;阻尼性能随R值增加而减少,玻璃化转变温度向高温方向移动,且材料软硬段相容性较好。     

硬段含量对水性聚氨酯性能的影响

以聚酯多元醇和异佛尔酮二异氰酸酯(IPDI)为主要原料，引入亲水单体二羟甲基丙酸(DMPA)，按不同配比合成了系列聚氨酯乳液。考察了硬段含量对乳液粒径、表观黏度、膜吸水性、硬度、力学性能的影响，并通过动态力学性能测试(DMA)研究了软段和硬段的玻璃化转变温度。结果表明：提高-NCP/-0H物质的量之比、DMPA用量均使聚氨酯中软段的玻璃化温度Tg(s)降低，硬段的玻璃化温度Tg(h)升高，△T值增加，软硬段相分离程度增加。随乙二胺用量的增加，会使软段玻璃化转变温度Tg(s)移向高温，软硬段相分离程度降低；硬段含量提高，胶膜硬度增加，拉伸强度增加，胶膜耐水性降低。     

硬段含量对聚氨酯和聚氨酯脲氢键化程度的影响

以PPG600,PPG2000,甲苯二异氰酸酯(TDI)和1,4-丁二醇(1,4-BD)为原料合成了聚氨酯(PU),通过改变PPG600,PPG2000配比调节产品硬段含量;以PPG2000,TDI和异佛尔酮二胺(IPDA)为原料合成了聚氨酯脲(PUU),通过调节TDI与IPDA在体系中的比例调节产品硬段含量。利用FT-IR,DSC,旋转黏度计研究了硬段含量对聚醚型PU和PUU的微观结构及黏度的影响。结果表明,随硬段含量提高,PU和PUU的氢键化程度均提高,PU较多地形成不完善的氢键,而PUU倾向于形成完善有序的氢键结构。此外随硬段含量增大,PU和PUU的黏度增大,PU软段的玻璃化转变温度升高。     

混合聚醚配比对聚氨酯脲结构和性能的影响研究

以PPG600和PPG2000混合聚醚、异佛尔酮二异氰酸酯（IPDI）和异佛尔酮二胺（IPDA）为原料合成溶剂型聚氨酯脲（Puu）树脂,通过改变PPG600和PPG2000配比调节树脂硬段含量。利用FTIR．DSC．TG等研究PPG600和PPG2000配比对聚氨酯脲微观结构、耐热性及力学性能的影响。结果表明,随着混合聚醚中PPG600含量增加,聚氨酯脲软段的玻璃化转变温度（Tg）升高,软硬段的相容性增强,脲羰基氢键化程度降低,树脂的定伸强度增大。     

不同硬段含量聚天冬氨酸酯聚脲结构和性能研究

通过聚天冬氨酸酯、端氨基聚醚与脂肪族异氰酸酯六亚甲基二异氰酸酯三聚体/预聚物反应,合成了纯硬段聚脲和不同硬段含量的聚脲,并考察了硬段含量对聚脲的结构形态、动态力学性质和力学性质的影响。硬段含量为73%~50%的聚脲呈现微相分离的形态,随着硬段含量降低,软段和硬段相的混合程度提高,脲羰基的氢键化程度增加,NH基氢键键长增加,硬段玻璃化转变温度Tgh降低,软段玻璃化转变温度Tgs的变化幅度较小,微相分离程度降低。材料的拉伸强度、模量和硬度随着硬段增加而提高,弹性则随之降低。     

磺酸基/羧基复合型水性聚氨酯研究进展

综述了目前国内外磺酸基/羧基复合型水性聚氨酯合成的研究进展,涉及在聚氨酯硬段中引入磺酸基/羧基(分开引入或同时引入)以及软段中引入磺酸基(磺化聚醚型软段及磺化聚酯型软段)/硬段引入羧基等途径并分析了该领域研究发展前景。     

硬段含量对水性聚氨酯氢键化程度的影响

以聚四氢呋喃醚二醇(PTMG-2000)、异佛尔酮二异氰酸酯(IPDI)、乙二醇(EG)、二羟甲基丙酸(DMPA)和乙二胺(EDA)为原料合成了不同硬段含量的水性聚氨酯(WPU).对FT-IR图谱中氨基与羰基区进行分峰处理,研究硬段含量对氢键化程度的定量影响,利用X射线衍射(XRD)、差示扫描量热(DSC)研究了硬段含...     

硬段含量对水性聚氨酯软段结晶性能的影响

以异佛尔酮二异氰酸酯、六亚甲基二异氰酸酯、聚己二酸丁二醇酯为主要原料合成了水性聚氨酯(WPU),通过FT-IR、DSC、XRD、SEM表征手段,研究了硬段含量对软段结晶性及WPU粘结性能的影响。研究表明,随着硬段含量的增加,WPU分子链上氨基甲酸酯键之间的氢键化程度提高,软硬两相相混严重,WPU软段结晶熔融焓变小,熔融温度变低;结晶衍射峰变弱,软段结晶性变差;粘结性能测试表明,在硬段含量较低时,聚氨酯体现出良好的结晶性能,初粘性较好。     

红外光谱法研究聚氨酯脲氢键

采用间苯二胺为扩链剂制备聚氨酯脲,研究其力学性能。随着硬段含量的增加,产物的硬度和强度均增加,而断裂伸长率下降。并用红外光谱法对氢键化程度进行表征,结果表明：随着硬段含量的增加,其脲羰基区氢键化程度增加。     

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.