煤焦油改性酚醛树脂的合成研究

采用正交试验法,探讨了不同物质的量比、反应时间以及催化剂用量对酚醛树脂性能的影响,并借助红外光谱(FTIR)对生成产物的结构进行分析,热重分析法(TCA)对其热稳定性进行表征.通过对改性后树脂的固含量和残炭率的测定分析,得到了合成树脂的优化条件:n甲醛:n苯酚=1.3:1,反应时间100min,NaoH用量为苯酚质量的1.1%.以煤焦油为改性剂时其改性,并对其固舍量、残炭率、水分及游离酚进行测定,结果表明,加入煤焦油后树脂的品质得到了提高.     

腰果酚改性酚醛树脂泡沫的制备

在碱性条件下,以腰果酚部分代替苯酚与甲醛反应制得腰果酚改性酚醛树脂,并以该树脂为原料制备腰果酚改性酚醛树脂泡沫。结果表明:当苯酚/腰果酚物质的量比为9/1、缩聚反应温度90℃、催化剂加入量为苯酚和腰果酚总质量4%时,所得树脂黏度为25 Pa·s,符合最佳发泡黏度范围。当苯酚/腰果酚物质的量比为9/1时,改性树脂在400℃时的残炭量(94.6%)要比未改性树脂的残炭量高7.1%,压缩强度由改性前的0.08 MPa提高到改性后的0.14 MPa。扫描电镜结果表明:在相同条件下,改性后的酚醛树脂泡沫泡孔更为均匀。     

EDTA改性无水酚醛树脂的合成

对用EDTA改性酚醛树脂进行了研究。通过研究确定了最佳的反应条件为n(苯酚):n(多聚甲醛):n(EDTA):n(Na OH)=1:1.3:0.01:0.05,反应时间为5h,树脂的固含量为88.5%,残炭量为46.2%,开始热分解温度为386℃,红外光谱显示该树脂为高邻位酚醛树脂。     

改性沥青树脂及其复合材料的制备及相关性能

以煤沥青为原料、三聚甲醛为交联剂,在对甲苯磺酸的催化作用下合成了沥青树脂（COPNA树脂）,通过添加酚醛树脂对其进行了改性;分别以沥青树脂和改性树脂为原料,与石墨混合制备了复合材料。考察了酚醛树脂含量对改性树脂的残炭率、甲苯不溶物含量、喹啉不溶物含量、p树脂含量的影响,以及树脂含量对复合材料的电阻率,肖氏硬度的影响;采用FT—IR和H—NMR研究其反应机理;采用TG研究了沥青树脂和改性树脂的热行为。研究表明,酚醛树脂与沥青树脂可以在一定比例范围内进行复配,在加热混合过程中酚醛树脂与沥青树脂发生化学反应,提高了沥青树脂的耐热性。经酚醛树脂改性的沥青树脂具有更高残炭率、更高β树脂含量和更好耐热性。改性后的树脂复合材料具有更高的电阻率、更高的肖氏硬度和更高的耐磨性。     

铜改性酚醛树脂的合成与表征

将Cu(铜)离子引入热塑性PF(酚醛树脂)中,采用配位反应法合成了Cu改性PF。研究结果表明:采用FT-IR(红外光谱)法和紫外分光光度法对Cu改性PF的结构进行了表征,初步得到Cu离子在PF中的配位结构。TGA(热失重分析)结果显示,改性树脂在255、535℃时具有明显的吸热现象,热失重速率增大,1 000℃时的残炭率为58%。与普通树脂相比,改性树脂的固含量和残炭率分别提高了5%和7%,说明其耐热性明显增强。     

溶胶凝胶法制备二氧化硅/酚醛树脂复合材料的性能

以硅烷偶联剂改性酚醛树脂为基体,正硅酸乙酯为前驱体,无水乙醇为共溶剂,盐酸为催化剂,采用溶胶凝胶法制备得到SiO_2/酚醛树脂复合材料。通过固含量、残炭率和力学性能测试以及红外光谱、热重分析和扫描电镜观察对制备的SiO_2/酚醛树脂复合材料的性能进行了研究。结果表明,材料的耐热性得到提高,无机粒子在树脂中分散均匀,没有团聚和孔洞。     

高固含发泡酚醛树脂的制备过程分析及应用研究

以多聚甲醛代替甲醛溶液制备高固含可发性酚醛树脂,研究了不同反应时间对高固含发泡酚醛树脂的性能影响。研究结果表明,随着反应时间的逐渐增加,所得产物的粘度和固体含量是逐渐增大的,游离苯酚和游离甲醛含量是逐渐减小的,耐热性略有降低;反应结束时,所得树脂的粘度、固体含量、游离苯酚、游离甲醛和900℃时的残炭量分别为8000m Pa·s、77.01%、1.42%、0.53%和60.14%,树脂的粘度适中,固体含量满足发泡树脂的要求,并且游离苯酚和甲醛含量较低,耐热性能较高,泡沫泡孔较小且分布较为均匀。     

高残炭酚醛树脂的研究进展

综述了高残炭酚醛树脂:硼改性、钼改性、芳基酚改性及硅氮烷改性酚醛树脂,酚三嗪树脂,苯并恶嗪树脂的研究进展。上述改性后的酚醛树脂,耐热性显著提高。这些研究为耐烧蚀材料的应用提供了理论依据,为新一代的高残炭树脂的开发提供了方向。最后指出酚醛树脂在今后的耐烧蚀材料领域仍然会发挥重要的作用。     

改性热塑性酚醛树脂的制备及残炭率的影响因素

在苯酚和甲醛原料中加入一定量的SiO2粉体改性剂,可成功制备出改性热塑性PF(酚醛树脂)。以热塑性PF的残炭率为考核指标,采用单因素试验法优选出制备硅改性PF的最优方案。结果表明,当m(苯酚)∶m(甲醛)=(1.30～1.36)∶1时,硅改性PF的残炭率较高且变化不大;当w(SiO2粉体)=0.9%、反应温度为90℃和反应时间为3 h时,改性热塑性PF的残炭率相对较高;此时,Si元素已均匀分布在PF基体树脂上,掺杂的SiO2有助于提高热塑性PF的耐热性能。     

腰果酚改性甲阶酚醛树脂的合成及其泡沫性能研究

用腰果酚代替部分苯酚改性酚醛树脂,制备可发性甲阶酚醛树脂。并讨论了腰果酚替代量对改性酚醛树脂性能及其泡沫性能的影响,通过红外光谱仪、热重分析仪对树脂结构及热稳定性进行表征,运用万能电子试验机对甲阶酚醛树脂泡沫的力学性能进行了研究。结果表明:当腰果酚替代量为10%时,制得的树脂黏度为4650mPa·s,树脂中游离苯酚含量从6.72%降为5.45%,游离甲醛含量从1.17%降为0.68%,甲阶酚醛树脂泡沫压缩强度达到最大值0.20MPa,但树脂热稳定性及甲阶酚醛树脂泡沫阻燃性有所下降。     

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.