书刊装订联动线用反应型聚氨酯热熔胶的研制

以聚酯多元醇、聚醚多元醇为软段,二异氰酸酯为硬段,辅以多种添加剂,制得一种性能优异的高结晶性单组分反应型聚氨酯(PUR)热熔胶。探讨了二异氰酸酯与多元醇的组成、投料比、扩链剂和添加剂等对产品性能的影响。结果表明:选用聚己二酸丁二醇酯二醇(PBA)为软段、1,4-丁二醇(1,4-BDO)为扩链剂以及4,4′-二苯基甲烷二异氰酸酯(MDI)为硬段,当R=n(-NCO):n(-OH)=(1.5～2.0):1.0、w(-NCO)=1%时,PUR热熔胶的软化点为85～95℃,开放时间为3～9 min,符合书刊装订联动线使用的技术要求,具有很好的应用前景。     

电子行业用反应型聚氨酯热熔胶的研究进展

介绍了电子行业用反应型聚氨酯热熔胶(PUR)的特点和优势。从反应型聚氨酯热熔胶的原材料及制备工艺、电子行业用反应型聚氨酯热熔胶、光/湿双固化和封端改性等几方面论述了国内外的技术进展。最后对电子行业用PUR的发展进行了展望。     

单组分聚氨酯反应型热熔胶制备与性能研究

以聚己二酸丁二醇酯二醇 (PBA) ,聚四氢呋喃二醇 (PTMG)及聚氧化丙烯二醇 (PPG)为软段 ,以 4,4’ -二苯甲烷二异氰酸酯 (MDI)和 1,4-丁二醇为硬软 ,制备了一系列快速固化单组分聚氨酯反应型热熔胶 ,考察了不同软段对热熔胶的粘接强度、耐水性、耐热性、结晶度等的影响。结果表明 ,以PTMG为软段制得的热熔胶具有较佳的综合性能     

聚醚型聚氨酯热熔胶膜的研制

以PTMG、BDO和MD I等为原料合成聚氨酯预聚物,分别考查了预聚反应的时间、温度等因素,确定了合适的反应条件为(80~90)℃/(2.5~3)h。采用流延法制备聚氨酯热熔胶膜,对影响聚氨酯热熔胶膜的拉伸强度、断裂伸长率、硬度的几个因素:聚醚多元醇类型、扩链剂用量和聚醚多元醇的分子质量等进行了研究。结果表明,选用相对分子质量为1 500的聚醚,BDO质量分数为6.1%~8.2%,制备的胶膜性能最佳。     

反应型聚氨酯热熔胶研究进展

介绍了近几年来反应型聚氨酯热熔胶的研究新成果,概述了石油基和生物基反应型聚氨酯热熔胶以及反应型热熔胶的脱除。综述了上述聚氨酯热熔胶所采用的原料、配方和合成工艺条件,并分析其凝胶时间、开放时间、耐热性、拉伸强度和硬度等性能,提出了反应型聚氨酯热熔胶的研究建议。     

聚醚腈型聚氨酯预聚体合成反应动力学研究

采用端羟基聚醚腈(HPCE)、甲苯二异氰酸酯(TDI)等为主要原料制备聚醚腈型聚氨酯预聚体,就其制备动力学进行了研究.提出了一种测试聚醚腈型聚氨酯预聚体合成中氨酯化反应和支化反应的反应动力学参数的理论模型,确定了合适的制备工艺.     

镀铝膜复合用反应型聚氨酯热熔胶内部气泡的抑制

反应型聚氨酯热熔胶作为镀铝膜复合包装用胶黏剂时,其内部容易产生鼓泡的现象。用聚酯多元醇、二异氰酸酯(MDI)为主要原料制备反应型聚氨酯热熔胶,研究异氰酸酯基质量分数(NCO的含量)、13X分子筛的用量、潜固化剂的用量对镀铝膜复合内部气泡的抑制,筛选出最佳的配方。采用扫描电镜(SEM)观察13X分子筛在聚氨酯材料中的分散情况,并且利用红外光谱对反应型聚氨酯固化前后的结构进行表征。     

聚氨酯热熔胶合成及应用研究的进展

综述了我国聚氨酯热熔胶的最新研究现状,重点介绍了光/湿双固化聚氨酯热熔胶、反应型聚氨酯热熔胶合成及应用研究的进展,最后指出了我国聚氨酯热熔胶的发展方向。     

本体法合成四类新型嵌段共聚物

由双端异氰酸酯聚醚预聚体与双端羟基聚硅氧烷或双端羟基聚砜共聚,或前两组分同时与双端羟基聚砜或羟基双酚A环氧进行本体嵌段共聚,可分别合成出四类嵌段共聚物,即聚醚型聚氨酯-聚硅氧烷嵌段共聚物,聚醚型聚氨酯-聚砜嵌段共聚物,聚醚型聚氨酯-聚硅氧烷-聚砜嵌段共聚物,聚醚型聚氨酯-聚硅氧烷-环氧嵌段共聚物。研究了该四类嵌段共聚物的合成及产品结构与形态。所得产品均具有微观相分离和两个玻璃化温度;通过小角激光光散射(SALS)测定表明,均具有V_v信息;经大角X-射线衍射(WAXD)测定,有些产品有结晶形成。     

聚硅氧烷改性聚氨酯密封胶预聚体的制备

采用甲苯二异氰酸酯(TDI)和聚氧化丙烯二醇(PPG)合成了端异氰酸酯基聚醚型聚氨酯密封胶预聚体,然后与端羟基硅油反应制备了单组分的聚硅氧烷-聚醚嵌段聚氨酯密封胶预聚体。考察了羟基硅油的加入量对改性聚氨酯胶外观、拉伸性能、低温性能和热稳定性等的影响。当低聚物二醇中羟基硅油的质量分数为15%时,改性聚氨酯胶的综合性能较好。此时,相分离的程度较小,且保留有较好的力学性能;玻璃化转变温度从-58.6℃降低到-79.8℃,低温性能得到改善;初始分解温度高于聚醚型聚氨酯胶。     

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.