马来酸酐改性蓖麻油制备耐光性聚氨酯复鞣剂——乳液性能研究

用马来酸酐改性蓖麻油(MCO)合成了一系列不同组成的耐光性聚氨酯复鞣剂水乳液(MC-PUR),研究了复鞣剂中—COOH质量分数、n(NCO)/n(OH)、m(MCO)/m(PEG1000)对乳液电导率、黏度、临界聚沉值(CC.C)、耐酸稳定性的影响。结果表明,随—COOH质量分数从3%增大到7%,电导率从1 556μs/cm增大到3 435μs/cm,黏度先从168 mPa.s增大到224 mPa.s,后又降低到85 mPa.s,当w(—COOH)=5%时,黏度达到最大值;随n(NCO)/n(OH)从0.5增大到0.9,电导率从2 943μs/cm降到2 464μs/cm,黏度从428 m Pa.s降到224 mPa.s;随m(MCO)∶m(PEG1000)从1∶1增大到3∶0,黏度从224 mPa.s降到67 mPa.s;CC.C随—COOH质量分数增加和m(MCO)/m(PEG1000)增大而降低;耐酸稳定性结果证明,当w(—COOH)=3%~5%,m(MCO)∶m(PEG1000)=1∶1,n(NCO)/n(OH)=0.5~0.9时,MC-PUR适用于皮革复鞣工序。     

纳米氧化锌的分散与表面改性研究

研究了纳米氧化锌在水体系中的分散及其分散后的表面改性处理。分别以聚乙二醇(PEG20000)和钛酸酯偶联剂(NDZ)为分散剂和表面改性剂,通过正交实验研究了分散剂、表面改性剂的用量以及球磨速度和研磨时间对分散稳定性和改性效果的影响。结果表明,最佳工艺条件为:1)分散过程中w(PEG20000)=0.5%,球磨速度为2 000 r/min、球磨时间为1 h;2)表面改性过程中w(NDZ)=1%、球磨时间为1 h、球磨速度为1 000 r/min。采用激光粒度测试仪及SEM对产物粒度及形貌进行了表征,改性后氧化锌颗粒以较小的粒径存在,分散性有明显的提高。     

微波熔盐法制备SiC改性石墨

为了改善石墨的水润湿性,使其在浇注料中易分散,以鳞片石墨和硅粉为原料,以NaCl-NaF为复合熔盐介质,采用微波熔盐法在石墨表面原位生成SiC涂层对其进行改性,并研究了反应温度(分别为1 100、1 150与1 200℃,均保温2 h)、石墨与硅粉的比例(n(C)n(Si)分别为1、3和5)以及复合熔盐与反应物料的比例(m盐m料分别为1、2和3)对SiC改性石墨润湿性的影响。结果表明:1)采用微波熔盐法,在1 150℃的较低温度下就可以在石墨表面形成均匀的SiC涂层,而经SiC改性后的石墨,其水润湿性得到了明显改善;2)在本试验条件下,当鳞片石墨与Si粉的比例为n(C)n(Si)=3,m盐m料=2,反应温度为1 200℃时,得到的改性石墨性能较好。     

改性氧化锌晶须对丁腈橡胶性能的影响

分别采用偶联剂(Si—69,NDZ—201,KH—550)对氧化锌晶须进行表面改性,研究了改性氧化锌晶须对丁腈橡胶性能的影响。结果表明:Si—69改性氧化锌晶须补强的NBR橡胶物理机械性能、耐老化性能、耐液体性能等优异,效果较KH—550和NDZ—201的好,用量为4份时硫化胶综合性能较好。     

硅烷偶联剂表面修饰四针状氧化锌晶须

利用硅烷偶联剂KH-570对四针状氧化锌晶须T-ZnOw表面进行了修饰,探讨了改性条件对改性效果的影响。用活化指数确定了改性的最佳工艺条件:盐酸为催化剂,水解时间1 h,偶联剂用量4%(相对于晶须用量),偶联温度70℃,偶联时间2 h。FTIR分析表明,偶联剂分子与晶须表面的羟基发生化学反应来实现对晶须的表面修饰,修饰后晶须疏水性明显增强。采用亲油化度、分散性实验对修饰前后T-ZnOw进行了表征。结果表明,改性样品分散性和亲油化度都得到显著改善。     

纳米白炭黑的复合改性及性能表征

为使纳米白炭黑具有强疏水性,在传统硅烷偶联剂改性工艺基础上,引入了硬脂酸进行复合改性,制备出了具有高疏水性能的纳米白炭黑。采用红外光谱(FTIR)、X射线光电子能谱(XPS)、接触角测试和沉降实验等研究了改性后试样的结构和性能,并讨论分析了复合改性的机理。结果表明:通过硅烷偶联剂改性,白炭黑表面接枝了氨基(—NH2)基团;硬脂酸改性后,—NH2基团与硬脂酸的羧基基团(—COOH)形成酰胺键(—CONH—),白炭黑最终表面形成了疏水性能优异的—(CH2)3COHN—(CH2)16CH3基团。复合改性后的纳米白炭黑表面通过化学键接枝了硬脂酸分子,与水的接触角达到了140°,具有优异的疏水性能。     

酸处理MWNTs对PBO／环氧界面性能的影响

多壁碳纳米管经过强氧化性酸的处理后,经XPS表征结果得出表面含有羧基的碳纳米管（MWNTs—COOH）。MWNTs—COOH经过超声处理后放入4,6-二氨基间苯二酚和对苯二甲酸的多聚磷酸体系中,原位聚合得到MWNTs—COOH／聚对苯撑苯并双嗯唑（PBO）复合材料,经液晶纺丝得到MWNTs—COOH／PBO纤维。用纤维界面分析仪测试MWNTs—COOH的加入对PBO纤维／环氧树脂界面剪切强度的影响。通过SEM和AFM对纤维的表面形貌进行观察,可看出MWNTs—COOH的加入改善了PBO与环氧树脂的界面强度。     

改性双氰胺衍生物环氧固化剂的制备及性能研究

分别采用环氧丙烷、环氧丙烷丁基醚(501)和环氧树脂(EP)对双氰胺(DICY)进行改性,制备了一系列新型的改性DICY衍生物作为EP固化剂,并对改性DICY/EP固化体系的性能进行了初步研究。结果表明:当反应温度为95～105℃、n(DICY)∶n(环氧丙烷)=1∶1.1和n(DICY)∶n(501)=1∶1.3时,环氧丙烷改性DICY(反应3.0 h左右)和501改性DICY(反应3.0～4.0 h)的收率较高;EP改性DICY的最佳反应条件为反应温度105℃左右、反应时间4.0 h左右和n(DICY)∶n(EP)=1∶1.3。环氧丙烷(或501)改性DICY在室温时具有一定的潜伏性,与EP的相容性得到明显改善,并且其固化体系的起始放热温度比DICY体系降低了近40℃(或30℃);EP改性DICY具有较好的潜伏性(与DICY相当),并且极易溶于EP中,但其固化体系的起始放热温度稍低于DICY体系。     

反渗透复合膜研究(Ⅱ)初生态膜的原位改性

界面聚合是制备超薄复合膜是通过两种互不相溶的单体溶液在多孔支撑的表面进行聚合,再经热处理,洗涤等工艺后得到超薄复合膜。初生态膜(IniM)是指完成界面聚合反应而未经后处理（热处理,洗涤等）的膜。采用间苯二胺和均苯三甲酰氯通过在多孔聚砜膜上界面聚合得到初生态反渗透复合膜,再用四乙烯五胺对初生态膜进行表面原位改性,经后处理得到改性反渗透复合膜。对改性反渗透复合膜面XPS分析结果为：改性膜表面的O/N比明显低于未改性的,这说明四乙烯五胺通过反应接枝在膜表面;同时,改性膜面接触角大于未改性膜的,进一步证明了这一点。脱盐性能测试结果为：改性反渗透复合膜的水通量和NaCl脱除率随着进水pH值的增大而减小,这与未改性的反渗透复合膜变化趋势完全相反;这是因为改性反渗透复合膜面含有氨基（—NH₂）或亚胺基（=NH）,当pH值增大时,其与水的亲和力减小;而未改性的反渗透复合膜表面含有羧基（—COOH）, 当pH值增大时,其与水的亲和力增大。     

纳米氧化锌的制备和表面改性

以七水硫酸锌和碳酸氢钠为主要原料,采用室温固相法结合微波热分解法制备了纳米氧化锌。为改善氧化锌微粒表面的物理化学性质,采用硬脂酸对氧化锌表面进行改性,探讨了硬脂酸改性纳米氧化锌粉体的工艺条件、表面改性机理及其对粉体颗粒亲油性的影响。采用红外光谱对改性后纳米氧化锌进行了表征,结果表明硬脂酸和纳米氧化锌之间以共价键结合,改性后纳米氧化锌能更好地分散在有机溶剂里。纳米氧化锌表面改性的最佳工艺条件:硬脂酸质量分数为10%,改性温度为60℃,改性时间为40 m in。     

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.