影响聚醚型异氰酸酯预聚体储存稳定性的因素

采用聚醚多元醇和甲苯二异氰酸酯合成了聚醚型异氰酸酯预聚体.通过调整反应物的最佳配比,选择适当的酸性阻聚剂合成了性能良好、储存稳定的预聚体,同时对影响预聚体储存稳定性的因素进行了讨论.     

包埋微生物用PUA预聚体的合成及其性能表征

以三官能度的水溶性聚醚多元醇和异佛尔酮二异氰酸酯(IPDI)、甲基丙烯酸羟乙酯(HE-MA)等为原料,合成了含双键、易乳化的聚氨酯丙烯酸酯(PUA)预聚体。探讨了聚醚多元醇相对分子质量、催化剂用量、阻聚剂用量对预聚反应和PUA预聚体性能的影响。结果表明,当聚醚多元醇相对分子质量为5100、催化剂用量为0.025%、阻聚剂对羟基苯甲醚用量为0.020%和添加酸性阻聚剂0.008%时,合成的预聚体粘度适中、贮存稳定、性能优良。生产的PUA预聚体通过了性能表征和应用评价,其所制备的包埋微生物的颗粒已经成功用于源水处理。     

异氰酸酯预聚体合成工艺的研究

采用H_(12)MDI和IPDI为异氰酸酯单体,聚四氢呋喃为聚醚多元醇,醋酸丁酯为溶剂,配制成异氰酸酯预聚体。讨论了反应原材料、反应温度以及溶剂含水量对反应过程和异氰酸酯预聚体性能的影响。分析了原材料配比与异氰酸酯基含量(—NCO%)和体系黏度的关系,最终确定了异氰酸酯预聚体的最佳合成工艺条件。     

聚缩水甘油苄基醚及其磺化物的合成与表征

用氢氧化钾做引发剂合成了不同分子量的聚缩水甘油苄基醚预聚体(PBzGE),对其碳谱进行了详细的归属,再用浓硫酸进行磺化,得到不同磺化度的磺酸聚醚(SPBzGE)。通过VPO,NMR,FT-IR测试了聚醚预聚体的分子量,并且对预聚体的结构进行了详细的归属。制得了分子量在1000～3000的预聚体,SPBzGE的磺化度大于110%。     

桥梁隧道灾害治理聚氨酯材料的制备及其性能研究

以聚醚多元醇、助剂、多亚甲基多苯基异氰酸酯(PAPI)、预聚体等为原料制备桥梁隧道灾害治理材料。探讨了助剂种类及用量、预聚体种类、预聚体NCO含量对材料力学及疏水性能的影响。结果表明：A组分由聚醚三醇a、聚醚二醇b、乙二醇、催化剂CAT 987和增塑剂TXIB配成；B组分由自制疏水型聚醚二醇c合成的NCO质量分数为23%的预聚体、PAPI和TXIB组成；TXIB在整个体系中质量分数为20%～25%,体系凝胶时间控制在7～9 min。固化后材料的压缩强度大于40 MPa,剪切强度大于3 MPa,水接触角控制在120°以上，能较好地应用于桥梁隧道灾害治理。     

噁唑烷潜固化剂改性聚氨酯预聚体性能研究

以改性二苯基甲烷二异氰酸脂和聚醚多元醇等为原料,合成了噁唑烷潜固化剂改性聚氨酯预聚体,讨论了预聚体的异氰酸酯基含量及噁唑烷潜固化剂用量对固化性能的影响。结果表明,通过傅立叶变换红外光谱(FT-IR)对预聚体成膜的固化动态进行了分析表征,当NCO基质量分数为2.3%、噁唑烷潜固化剂质量分数为2.5%～3.5%时,预聚体固化时不产生发泡膨胀;固化20h后反应完全。     

聚醚型聚氨酯预聚体合成工艺研究

以聚醚多元醇和异氰酸酯为原料合成聚氨酯预聚体。通过测定—NCO的含量,研究了预聚反应时间和反应温度对预聚反应的影响;研究了R值[n(—NCO)/n(—OH)],反应时间和温度对预聚物黏度的影响,并探讨了预聚反应过程中含水量、预聚体贮存时间对弹性体性能的影响。     

光固化聚氨酯型阴极电泳清漆的研究

以甲基异丁基酮作为起始溶剂,用聚丙二醇扩链IPDI得到聚氨酯预聚体.将三乙醇胺引入聚氨酯预聚体中使其阳离子化,利用含羟基的内烯酸酯类封端为树脂提供光敏基团,合成出漆膜性能优异的光固化聚氨酯型阴极电泳清漆.通过检测电泳漆膜的性能,确定了光固化阳离子聚氨酯树脂中聚醚的相对分子质量、封闭剂的种类和用量、稳定剂的加入、溶剂体系.该电泳清漆可以应用在各种小五金涂装领域,具有环保,固化快速的特点.     

新型汽车密封胶用聚醚多元醇的合成及其应用

以丙二醇和甘油为混合起始剂,合成了一种新型汽车密封胶用聚醚多元醇,并与二苯基甲烷二异氰酸酯反应合成了聚氨酯预聚体密封胶,探讨了催化剂、温度等因素对聚醚多元醇及预聚体的影响。结果表明,此聚醚多元醇反应活性比传统三官能度聚醚更稳定,降低了预聚体的聚釜风险,并提高制品的拉伸强度和断裂伸长率。     

影响聚醚型聚氨酯预聚体合成的因素

以聚乙二醇（PEG）和二异氰酸酯为原料，通过测定-NCO的含量，确定了预聚反应的时间和温度，合成了聚醚型聚氨酯预聚体；对影响预聚体合成的因素：异氰酸酯的种类、n（-NCO）：n（-OH）、二异氰酸酯的自聚、水分的含量以及预聚体的贮存稳定性等进行了研究。     

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.     

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.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.