Development and evaluation of terminally epoxidized triglycerides for coatings applications

Epoxidized 10-undecenoic acid triglyceride, an experimental seed oil derivative that has a terminal epoxy group on each of the three acyl glyceride segments, has been found to have good reactivity with amine curatives and allows room temperature cures to be obtained. Coatings based on epoxidized 10-undercenoic acid triglyceride have also shown excellent UV stability. As an example, coatings samples placed in a QUVA chamber exhibit no loss in gloss after 3000 hr of a cycled exposure to high intensity UV lamps and moisture at temperatures of 50–60°C. In comparison, coatings based on standard liquid epoxy resins (LERs) and commercially available hydrogenated LERs lose gloss due to chalking/decomposition within 200–800 hr. Presented at the 81 st Annual Meeting of the Federation of Societies for Coatings Technology, November 12–14, 2003, in Philadelphia, PA.     

Two-component high-solid polyurethane coating systems based on soy polyols

Soybean oil based polyols—soybean oil phosphate ester polyols (SOPEPs)—having varying hydroxyl content and viscosity were prepared as low cost and low-VOC polyols for coatings applications. These SOPEPs were used as the hydroxyl component of “two-component polyurethane (2K-PU)” coating compositions and their film properties were studied. Blends of commercial polyester polyol and SOPEP in varying proportions were also used to formulate PU coatings. Their film properties were studied and compared. We found that SOPEP can be used as the sole hydroxyl component or as the reactive diluent for polyester polyols in 2K-PU coating systems. SOPEP, is derived from a relatively inexpensive and renewable resource and the use of SOPEP can substantially reduce VOC and cost of PU coating formulations. Presented at the International Waterborne, High-Solids, and Powder Coatings Symposium, New Orleans, LA, February 2002.     

Advanced techniques for nanocharacterization of polymeric coating surfaces

Surface properties of a polymeric coating system have a strong influence on its performance and service life. However, the surface of a polymer coating may have different chemical, physical, and mechanical properties from the bulk. In order to monitor the coating property changes with environmental exposures from the early stages of degradation, nondestructive techniques with the ability to characterize surface properties with micro- to nanoscale spatial resolution are required. In this article, atomic force microscopy has been applied to study surface microstructure and morphological changes during degradation in polymer coatings. Additionally, the use of AFM with a controlled tip-sample environment to study nanochemical heterogeneity and the application of nanoindentation to characterize mechanical properties of coatings surfaces are demonstrated. The results obtained from these nanometer characterization techniques will provide a better understanding of the degradation mechanisms and a fundamental basis for predicting the service life of polymer coatings. Presented at the 81st Annual Meeting of the Federation of Societies for Coatings Technology on November 12–14, 2003, in Philadelphia, PA.     

Plant oil polyol nanocomposite for antibacterial polyurethane coating

Some preliminary investigations on “green” preparation, morphology and antibacterial behavior of Linseed polyol nanocomposite [LMPOL] for antibacterial polyurethane coatings are summarised. Nanocomposite is prepared in situ with Linseed polyol [LP] matrix as organic and Copper acetate as inorganic constituent by “solventless one-pot” chemical reaction. The presence of characteristic absorption bands in FTIR spectra confirmed the formation of LMPOL. TEM analysis showed the presence of nano-sized metal oxide in LMPOL. LMPOL showed good antibacterial behavior against E. coli and S. aureus. The interactions between LMPOL and bacterial surfaces lead to good antibacterial efficacy, suggesting membrane disruption based cell death. LMPOL may serve as an excellent starting material for antibacterial polyurethane coating. The approach is an excellent example for the preparation of “green” polyol from “green” resource en route Green Chemistry for protective polyurethane coatings.     

The chemistry and physics of coking

The causes of coke formation during petroleum refining are only now beginning to be understood. They are closely related to the mechanism of the thermal decomposition of the petroleum Constituents and to changes in the character of the liquid medium. It was formerly believed that coke formation was, a polymerization reaction whereupon the chemical precursors to coke immediately formed macromolecules when subject to the processing temperatures. This is not so. And it is the initial stages of the thermal decomposition which determine the ultimate path of the reaction. Coke formation is a complex process involving both chemical reactions and thermodynamic behavior. Reactions that contribute to this process are cracking of side chains from aromatic groups, dehydrogenation of naphthenes to form aromatics, condensation of aliphatic structures to form aromatics, condensation of aromatics to form higher fused-ring aromatics, and dimerization or oligomerization reactions. Loss of side chains always accompanies thermal cracking, and dehydrogenation and condensation reactions are favored by hydrogen deficient conditions.     

Synthesis,crosslinking, and characterization of energetic polymers through the azidification of glycidyl ether prepolymers

Low‐molecular‐weight atactic poly(propylene oxide) and poly(epichlorohydrin) (PECH) were chlorinated on average up to 4.42 chlorine atoms per repeat unit. A study of the products showed that chlorine substitution preferentially occurred on already chlorinated repeat units, yielding chlorine ‐rich and chlorine ‐poor sequences. As the extent of chlorine substitution increased, the glass‐transition temperature of the polymers markedly increased, and their solubility in most of the organic solvents drastically decreased. The chlorinated polymers were azidified with NaN₃ in dimethyl sulfoxide solutions. An analysis showed that azide groups replaced 99.8–99.9% of the initially present chlorine atoms. As the azide content of the samples increased, initially opaque polymers become dark brown, and their solubility increased in water but decreased in organic solvents. Samples with approximately four or more azide groups per repeat unit were only soluble in dimethyl sulfoxide and water. The standard enthalpy of formation of the polymers became increasingly positive as the azide content increased. The enthalpy of formation of a sample with 4.42 N₃/repeat unit was 6929 kJ/repeat unit, whereas this value was only 103 kJ/mol for classical GAP. An azidified sample from PECH (4.42 N₃/repeat unit) was crosslinked with a commercial triisocyanide into a rubbery product. The density and ultimate tensile strength of the rubbery product were 1.44 g/cm³ and 4.84 MPa, and it swelled about 10% at 20°C in water.© 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3785–3790, 2004     

Application of quaternary ammonium salt as catalyst in the reaction of glycidyl methacrylate with CO2

This study is related to the investigation of the characteristics of quaternary ammonium salt catalyst on the addition reaction of carbon dioxide and glycidyl methacrylate (GMA) to form (2-oxo-l,3-dioxolan-4-yl) methyl methacrylate (DOMA). Among the salts tested, the ones with higher alkyl chain length and with more nucleophilic counter anion showed a higher catalytic activity. The DOMA monomer was obtained in non polar solvent like toluene and cyclohexane, while poly (DOMA) could be directly obtained in aprotic dipolar solvent such as DMF. In order to facilitate recovery of catalyst, polymer-immobilized quaternary ammonium salt was prepared by copolymerization of styrene (ST), divinylbenzene (DVB) and vinyl benzene chloride (VBC). The catalyst with 2 wt% of DVB, 25 wt% of VBC and quaternized tributyl amine showed the highest catalytic activity, and its activity was maintained even up to 10 successive experimental runs.     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.     

Modeling, prediction, and analysis of alkyd enamel coating properties via neural computing

The use of artificial neural networks (ANNs) in the modeling and prediction of alkyd enamel coating properties, as well as in the sensitivity analysis that can be performed between the properties and the different paint components, are described. A feedforward neural network with sigmoidal activation functions was used with a conjugate gradient algorithm to recognize the complex input-output relation between the paint properties and the formula components. We restricted the study to only two properties of alkyd enamel paints: gloss and drying time. A database of five different families of alkyd enamel paints, containing the different components of the formulations as well as process information, was used in this study. The results obtained show, within the expected uncertainty tolerance, that predictive power of more than 90% for these two properties can be achieved. A sensitivity analysis was also performed using ANNs, yielding the relative importance of the different components of the formulation on the properties of the enamel coatings, which agrees with experience for gloss but gives mixed results for the drying time (apparently due to the high uncertainties in the measurement of this property).     

锌粉和有机硅对聚氨酯涂层耐蚀性和热性能的影响

通过浸泡腐蚀和高温烘烤,以涂层的冲击强度为依据,研究了不同锌粉含量的聚氨酯涂层在10%(质量分数,下同)HCl、10%NaOH和20%NaCl溶液中的耐腐蚀性以及不同有机硅添加量的涂层在120℃下的耐热性.通过热重分析(TG-DSC),比较了改性前后聚氨酯涂料的热稳定性,测试了涂层的综合性能.结果表明,含锌量为83%的...     

Novel Chitinolytic Enzymes with Biological Activity Against Herbivorous Insects

The soil bacteria, Streptomyces albidoflavus, secretes endochitinases and chitobiosidases that are active over a broad range of pH (4–10). Ingestion of this mixture of chitinolytic enzymes significantly reduced the growth and development of Trichoplusia ni and significantly reduced survival of Myzus persicae, Bemisia argentifolii, and Hypothenemus hampei. Perfusion chromatography was used to separate endochitinases from chitobiosidases. The endochitinases had significantly greater biological activity against Bemisia argentifolii than the chitobiosidases. The utility of chitinolytic enzymes as regulators of populations of herbivorous insects is discussed.     

Simultaneously increasing cryogenic strength, ductility and impact resistance of epoxy resins modified by n-butyl glycidyl ether

Epoxy resins are increasingly used in cryogenic engineering areas due to rapid developments of spacecraft and superconducting cable technologies as well as large cryogenic engineering projects (e.g., International Thermonuclear Experimental Reactor). Cryogenic mechanical properties are important parameters for epoxy resins to be employed in such areas. In this paper, a traditional reactive aliphatic diluent, namely n-butyl glycidyl ether (BGE, JX-013) with a low viscosity, was used to modify diethyl toluene diamine (DETD)-cured diglycidyl ether of bisphenol-F (DGEBF) epoxy system for enhancing cryogenic mechanical properties at liquid nitrogen temperature (77 K). The results showed that the cryogenic strength, ductility and impact resistance (impact strength) have been simultaneously enhanced by the addition of BGE with appropriate contents. Moreover, the comparison of the mechanical properties between 77 K and room temperature (RT) indicated that at the same composition, the tensile strength and Young's modulus at 77 K were higher than those at RT but the failure strain and impact resistance showed the opposite results. Finally, differential scanning calorimetry (DSC) exhibited that the glass transition temperatures (T_g) of the epoxy resins decreased with increasing the BGE content.     

Thermal decomposition of polyester polyurethane and its elastomers exposed to γ-radiation

The thermal-decomposition parameters of unplasticized and nitrate ester plasticized polyester polyurethane elastomers with unsaturated carbon—carbon bonds in the initial state and after irradiation with doses of 120–380 kGy (γ-quanta ⁶⁰Co) were determined using dynamic thermogravimetry and differential scanning calorimetry. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 2, pp. 133–138, March–April, 2006.     

Phytoecdysteroids: A Novel Defense Against Plant-Parasitic Nematodes

The phytoecdysteroid, 20-hydroxyecdysone (20E), is a major molting hormone of invertebrates, possibly including nematodes. As 20E is inducible in spinach, the defensive role against plant-parasitic nematodes was investigated. The effects of direct application on nematodes was assessed by treating cereal cyst nematode, Heterodera avenae, juveniles with concentrations of 20E from 8.2 x 10(-8) to 5.2 x 10(-5) M before applying to Triticum aestivum growing in sand. H. avenae, Heterodera schachtii (sugarbeet cyst nematode), Meloidogyne javanica (root-knot nematode), and Pratylenchus neglectus (root lesion nematode) were treated with 5.2 x 10(-5) 20E and incubated in moist sand. To test the protective effects of 20E in plants, the latter three nematodes were applied to Spinacia oleracea in which elevated concentrations of 20E had been induced by methyl jasmonate. Abnormal molting, immobility, reduced invasion, impaired development, and death occurred in nematodes exposed to 20E either directly at concentration above 4.2 x 10(-7) M or in plants. Phytoecdysteroid was found to protect spinach from plant-parasitic nematodes and may confer a mechanism for nematode resistance.     

Novel chemistry of abdominal defensive glands of nymphalid butterfly Agraulis vanillae

Abdominal defensive glands of both sexes of the Gulf fritillary butterfly, Agraulis vanillae (Linnaeus) (Nymphalidae:Heliconiinae)emit a pronounced odor when disturbed. We have identified 6-methyl-5-hepten-2-one; oleic, palmitic, and stearic esters of the corresponding alcohol 6-methyl-5-hepten-2-ol; hexadecyl acetate; 1,16-hexadecanediol diacetate; and 1,15-hexadecanediol diacetate in the glandular exudate. Since we have determined that free-flying birds or birds in a butterfly conservatory discriminate against A. vanillaeas prey, we suggest that the constituents in the glands may play a defensive role against potential avian predators.     

Hyperbranched azo polyurethane synthesized through A2 + B3 scheme

A hyperbranched azo polyurethane was synthesized by one-step polymerization of an A₂ type monomer diphenylmethane-4,4′-diisocyanate and a B₃ type monomer 4-(N,N′-bis(2-hydroxyethyl))amino-2′-hydroxyethoxyl-4′-nitro-azobenzene. The azo polymer was characterized by ¹H nuclear magnetic resonance (NMR), ultraviolet-visible (UV-Vis) spectrum and thermal analysis. The λ_max of the polymer in dimethylformamide (DMF) solution is 488 nm. The number average molecular weight (M_n) determined by GPC is 9,300 with a polydispersion index 1.9. The glass transition temperature (T _g) of the polymer is 131°C observed from DSC thermogram. The results show that the azo polyurethane has been successfully synthesized through this scheme. Surface-relief-gratings (SRGs) were fabricated on the polymer film after being irradiated by interference pattern of Ar⁺ laser beams for 1,000 s. The surface modulation depth and the grating space period measured by AMF are 67 and 770 nm, respectively. __________ Translated from Acta Polymerica Sinica, 2007, 1: 21–25 [译自: 高分子学报]     

A Novel Approach for Isolation of Volatile Chemicals Released by Individual Leaves of a Plant in situ

A glass chamber designed specifically for collecting volatile chemicals from individual leaves of a plant in situ is described. The effectiveness of the chamber was demonstrated by collecting volatile chemicals from single leaves of two plant species, potato (Solanum tuberosum) and broad bean (Vicia faba), before and after mechanical damage. The glass chamber, in conjunction with thermal desorption, enables reduction of the entrainment time and thereby allows the monitoring of compounds released by leaf damage in successive 5-min periods. An intact broad bean leaf, in the middle of the day, produces small amounts of the green leaf volatiles (E)-2-hexenal and (Z)-3-hexen-1-ol. However, during the first 5 min after mechanical damage, large amounts of (Z)-3-hexenal, (E)-2-hexenal, and (Z)-3-hexen-1-ol are produced. The decline in production of (Z)-3-hexenal and (E)-2-hexenal is fast, and after 10 min, these compounds reach very low levels. (Z)-3-Hexen-1-ol shows an increase for the first 10 min and then a gradual decline. An intact potato leaf, in the middle of the day, produces very small amounts of the sesquiterpene hydrocarbons -caryophyllene and germacrene-D. After being damaged, the profile of released volatiles is different from that of broad bean. In potato, damage is associated with release of large amounts of green leaf volatiles and sesquiterpene hydrocarbons. Compounds such as (Z)-3-hexenal, (E)-2-hexenal, and (Z)-3-hexen-1-ol are released in high amounts during the first 5 min after damage, but after 10 min, these drop to very low levels. High release associated with damage is also observed for -caryophyllene, (E)--farnesene, germacrene-D, and -bisabolene. The highest level is reached 5 min after damage and 15 min later, these compounds drop to low levels. The significance of compounds released after plant damage is discussed.     

Enhancing exterior performance of clear coatings through photostabilization of wood. Part 2: coating and weathering performance

Clear-coated boards have not been recommended for use in exterior conditions since irradiation with visible and UV radiation darkens them and photodegrades the lignin in the wooden surface beneath the coating, leading to delamination and subsequent catastrophic coating failure due to the continued action of sun, rain, and biological factors. Many approaches to rectify this problem have been explored. Chemical modification of the surface with hexavalent chromium, reaction with various anhydrides, grafting of UV absorbers, and esterification are among the methods attempted. A second approach has been via the clear coating itself where UV absorbers, antioxidants, and ultrafine titanium and iron oxides have been added. However, these have had limited or no success in stopping photodegradation processes. Since the main cause of photodegradation is photooxidation of lignin in the wooden surface as a consequence of free radical reactions initiated by UV irradiation, the approach taken in the present study, in an attempt to enhance the weathering performance of clear-coated boards outdoors, was to delignify the surfaces of wooden boards and then apply clear coatings to try and retard possible photodegradation. Two different pretreatments were used. Firstly, chemical surface delignification with a peracetic acid treatment created a partial delignification to a depth of 2–3 mm while still retaining the structural integrity of the surface. Secondly, a preweathering treatment, which resulted in a 100-μm-deep delignification zone, was compared. The coatings applied to the exposure surface of the pretreated boards were either polyurethane or an acrylic varnish. The clear-coated boards were exposed to exterior and accelerated weathering regimes for 3 years or 3000 h, respectively. Pretreated coated boards did not darken and yellow on exposure but untreated coated boards did. However, despite apparently arresting photodegradative processes on board surfaces, there were no significant gains in the performance ratings of coated pretreated boards over those of coated untreated control boards. Explanations for this involve the effectiveness of design factors incorporated into boards for exposure trials. These factors were the fungicidal dipping of boards before coating, precoating the exposure surface with a reactive primer, and applying a full polyurethane system to the back side and edges of boards. Both pretreatments resulted in clear-coated board surfaces that performed very similarly on exposure outperforming systems reported previously. It was surprising to observe that the preweathering treatment, which resulted in a 100-μm-deep delignification zone, performed as effectively as the chemically pretreated boards with 2- to 3-mm treatment zone. However, preweathered surfaces had lost all lignin in the middle lamella and there was cell separation, whereas in peracetic acid-treated boards, there was more or less complete lignin removal from the cell corner middle lamella only and partial lignin removal from other cell wall regions. Furthermore, it is anticipated that refinements in treatment methods and coating formulations will bring desired benefits and future work should focus in this area.     

Characterization of a chromate-inhibited primer by doppler broadening energy spectroscopy

A chromate-inhibited primer has been characterized by Doppler broadening energy spectroscopy (DBES), scanning electron microscopy (SEM), and Raman spectroscopy. The S-parameter obtained by DBES exhibited a three-layer depth profile, which is attributed to the presence of a “skin” layer in the polymer matrix of the primer and a concentration gradient in the inorganic phases distributed through the primer. The primer was also examined by DBES following immersion in solution. The change observed in the S-parameter upon immersion indicated water filling the molecular free volumes in the primer. The ability to monitor the depth of water uptake as a function of immersion time illustrates that the primer does not need to be fully saturated for chromate release to occur.     

Evaluation of Mesua ferrea L. seed oil modified polyurethane paints

Two types of stoving paints have been prepared from Mesua ferrea L. seed oil (MFLSO) modified poly(urethane ester) (PUE) binder systems. One stoving paint system was prepared from partially butylated melamine formaldehyde (MF) resin modified MFLSO-based PUE (70:30 weight ratio) and other one comprised of bisphenol-A-based epoxy resin modified with MFLSO-based PUE (50:50 weight ratio). Paints made with these two resin systems as binders were evaluated against the standard paint system. The physical properties of the paint systems viz. non-volatile content, specific gravity, viscosity, drying time, flexibility, adhesion, scratch hardness, gloss, etc. and chemical properties such as corrosion resistance, salt spray resistance, UV resistance, etc. were measured as per the standard methods and were compared. Thermal stability and surface morphology of the paints were also studied by using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. The performance characteristics of both the test paints were found to be comparable with the corresponding industrial standard paints. Out of the two test paints, the epoxy modified PUE-based stoving paint has been found to be preferred.