Vinyl esters lead the corrosion challenge

50 years of in-service experience means composites are no longer considered ‘the last resort’ for corrosion resistant applications. Amanda Jacob reports on how the latest developments in vinyl ester resins are helping to advance composites into even more applications. Amanda Jacob reports.     

Vinyl esters of some aldehydic acid acetals

Vinylation of azelaaldehydic and brassylaldehydic acid cyclic acetals from ethylene glycol gave excellent yields of the vinyl esters. Under conditions of the vinyl exchange reaction used, acyclic acetals from monohydric alcohols cleaved to give enol-ethers as major, inseparable impurities. Radical-initiated polymerization of the pure vinyl esters of the aldehydic-acid cyclic acetals resulted in crosslinking when initiation was by either peroxide or azobis (isobutyronitrile). Presented at the AOCS Meeting, Toronto, October 1962. A laboratory of the No. Utiliz. Res. Dev. Div., ARS, USDA.     

Vinyl esters of 4-aroyl butyric acids and their polymers

Vinyl 4-benzoyl butyrate, vinyl 4-(p-toluoyl) butyrate and vinyl 4-(m-nitro-benzoyl) butyrate were prepared by vinyl interchange with vinyl acetate. Theoptimum conditions for the preparation of these monomers have been studied.Their structures were established by NMR spectroscopy. The polymers of thesemono em were synthesised by free radical polymerization, their molecular weightsand glass temperatures determined. Vinyl 4-(m-nitrobenzoyl) butyrate was not-polymerizable. Vinyl 4-benzoyl butyrate showed degradcttive transfer reaction on polymerization due to the presence of active methylene groups.     

Vinyl chloride–vinyl acetate kinetic modeling. I. Determination of radical efficiency factor

Using dead end polymerization procedures, the copolymerization of vinylchloride–vinyl acetate was studied in laboratory scale reactors. Predictive kinetic models based on modified Hamielec equations were developed which were valid up to the limit of the experiments, 35% conversion. The efficiency factor (f) for the t-butylperneodecanoate initiator was determined for a range of initiator concentrations in a comonomer mixture.     

Kinetic study of the reaction between tocopheroxyl radical and unsaturated fatty acid esters in benzene

A kinetic study of the reaction between a tocopheroxyl radical and unsaturated fatty acid esters has been undertaken. The rates of allylic hydrogen abstraction from various unsaturated fatty acid esters (ethyl oleate2, ethyl linoleate3, ethyl linolenate4, and ethyl arachidonate5) by the tocopheroxyl radical (5,7-diisopropyltocopheroxyl6) in benzene have been determined spectrophotometrically. The second-order rate constants, k₃, obtained are 1.04×10⁻⁵ M⁻¹s⁻¹ for2, 1.82×10⁻² M⁻¹s⁻¹ for3, 3.84×10⁻² M⁻¹s⁻¹ for4, and 4.83×10⁻² M⁻¹s⁻¹ for5 at 25.0°C. Thus, the rate constants, k_abstr/H, given on an available hydrogen basis are k₃/4=2.60×10⁻⁶ M⁻¹s⁻¹ for2, k₃/2=9.10×10⁻³ M⁻¹s⁻¹ for3, k₃/4=9.60×10⁻³ M⁻¹s⁻¹ for4, and k₃/6=8.05×10⁻³ M⁻¹s⁻¹ for5. The k_abstr/H values obtained for the polyunsaturated fatty acid esters3,4, and5 containing H-atoms activated by two π-electron systems are similar to each other, and are about three orders of magnitude higher than that for the ethyl oleate2 containing H-atoms activated by a single π-system. From these results, it is suggested that the prooxidant effect of α-tocopherol in edible oils and fats may be induced by the above hydrogen abstraction reaction.     

乙烯-乙酸乙烯酯共聚物中乙酸乙烯酯的红外光谱法测定

利用ATR技术测量样品的红外光谱,采用偏最小二乘法对所测光谱进行分析,建立了一种快速分析方法;对乙烯-乙酸乙烯酯共聚物中乙酸乙烯酯进行测定。结果表明：标准曲线线性关系良好,相关系数为0．99985,方法简单快速,结果可靠。     

Photolytic and free‐radical polymerization of cinnamate esters of epoxidized plant oil triglycerides

Epoxidized soybean oil was reacted with cinnamic acid with triphenyl phosphine as a catalyst. Cinnamic acid reacted with 79% of the available epoxy groups, and this yielded cinnamate esters of epoxidized soybean oil (ESOCA). ¹H‐NMR, IR, and mass spectra of the new cinnamate derivatives confirmed the proposed structure. The mass spectra revealed that the average number of cinnamate groups per triglyceride molecule was 3.33. ESOCA could be photopolymerized with UV light. ESOCA could also be homopolymerized into a soft and insoluble polymer by free‐radical initiation and copolymerized with styrene, vinyl acetate, and methyl methacrylate. A mixture of ESOCA with 25 wt % styrene had a viscosity of 410 cP and could be free‐radically polymerized with benzoyl tert‐butyl peroxide at elevated temperatures. Differential scanning calorimetry confirmed the formation of copolymers. The ESOCA homopolymer and its copolymers all showed a first‐order transition by differential scanning calorimetry around ?1.5°C that was attributable to side‐chain relaxations of the triglyceride fatty acids. The styrene copolymer of ESOCA showed a tan δ peak at 66.6°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3882–3888, 2003     

Free radical addition of hydrogen sulfide to conjugated and nonconjugated methyl esters and to vegetable oils

The rate of addition of hydrogen sulfide to high purity methyl oleate, methyl linoleate, methyl linolenate, methyl 9,11-trans,trans-octade-cadienoate and methyl β-eleostearate was investigated at 25 C with UV irradiation. A similar study was carried out with soybean, linseed and tung oils in the absence and presence of 2,2′-azo-bis(isobutyronitrile) with UV photolysis. Initially the reaction of hydrogen sulfide with methyl esters appears to follow pseudo-zero-order kinetics although as the reaction proceeds the kinetics of the polyunsaturated ester reactions become more complex. For nonconjugated systems the overall rate is determined by the initiation step, whereas the overall rate of addition to conjugated systems is a function of the stability of the resonance-stabilized addition radical in the chain transfer step. For methyl esters the following order of reactivity appears to hold: Methyl oleate ≅ methyl linoleate ≅ methyl linolenate >> methyl 9,11-trans,trans-octadecadienoate > methyl β-eleostearate. Using 2,2′-azo-bis(isobutyronitrile) with UV photolysis markedly increases the rate of addition of hydrogen sulfide to nonconjugated vegetable oils. Presented at the AOCS Meeting, New York, October 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Photolytic and free‐radical polymerization of monomethyl maleate esters of epoxidized plant oil triglycerides

Epoxidized soybean oil (ESO) was reacted with monomethyl maleate with AMC‐2 catalyst. Monomethyl maleate was found to react with 65% of the available epoxy groups to give the monomethyl maleic esters of ESO (MESO). ¹H‐NMR, ¹³C‐NMR, and IR spectra of the new derivative confirmed the proposed structure. The NMR spectra revealed that the average number of monomethyl maleate groups per triglyceride molecule was 2.6. MESO was photopolymerized with ultraviolet light and was free radically homopolymerized and copolymerized with styrene (STY), vinyl acetate (VA), and methylmethacrylate (MMA). MESO was also reacted with maleic anhydride at the newly formed hydroxyl groups to give maleinized MESO, (MESOMA), which now contained 4.9 maleate unsaturations per triglyceride. Dynamic mechanical analysis revealed the dynamic modulus for styrene copolymers of MESO and maleinized MESO as 105 and 140 MPa, respectively. Both of these plant oil derived monomers are good candidates for a practical and economical liquid molding resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 626–633, 2007     

Molecular shape recognition-structure correlation in a phenylalanine-based polymer-silica composite by surface-initiated atom transfer radical polymerization

A polymerizable l-phenylalanine-derived monomer (N′-octadecyl-N^α[4-(acryloyloxy)-butanoyl]-l-phenylalanineamide (3)) has been newly synthesized and characterized. We reported an advanced approach to molecular shape recognitive hybrid materials that involves immobilization of radical initiator on mesoporous silica particles (average diameter, pore size and surface area are 4 μm, 12 nm, and 300 m² g⁻¹, respectively) and surface-initiated atom transfer radical polymerization of monomer 3 from initiator-grafted particles. All samples were characterized by elemental analysis, thermogravimetric analysis, diffuse reflectance infrared Fourier transform spectroscopy, solid state NMR measurements (¹³C CP/MAS NMR and ²⁹Si CP/MAS NMR), differential scanning calorimetry and scanning electron microscopy. The obtained polymer-silica hybrid material was used as a stationary phase for reversed-phase high performance liquid chromatography (RP-HPLC) to investigate its molecular shape recognition ability towards polycyclic aromatic hydrocarbons (PAHs). The new composite material showed better planarity selectivity than octadecylsilane stationary phase as a conventional RP-HPLC packing material and also enhanced linearity selectivity compared with the recently reported poly(N′-octadecyl-N^α-(4-vinyl)-benzoyl-l-phenylalanineamide)-grafted silica. Such selectivity enhancement can be attributed to the combination of hydrophobic effect due to octadecyl chains and multiply carbonyl π-benzene π interaction between the amide groups of the stationary phase and delocalized electrons of PAHs.     

氯醚树脂的制备及其在涂料中的应用研究进展

综述了氯醚树脂的结构和性能、合成工艺、改性方法及其在涂料中的应用研究进展,阐述了以悬浮聚合和乳液聚合制备氯醚树脂的一些方法,其中乳液聚合法既可以采用水溶性热引发剂体系也可采用氧化 -还原引发体系。目前,对溶剂型 /水性氯醚树脂的改性方法主要以丙烯酸树脂、环氧树脂及纳米二氧化硅和纳米二氧化钛等为主,改性后的氯醚树脂的性能显著提高,这拓宽了氯醚树脂的应用范围,目前主要的应用方向为防腐涂料、防污涂料、防火涂料乃至导电涂料等领域。     

The reactions of hydrogen bromide with oleic acid and its esters. II. Free radical addition

Summary Oleic acid and a series of its esters were reacted with hydrogen bromide under conditions favoring addition by a free radical mechanism. Variations of the solvents, catalysts, temperatures, dilution, and the ester groups were investigated. Under all conditions a statistical 50∶50 distribution of position isomers was found. This paper comprises parts of a dissertation submitted by Eric Jungermann in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Polytechnic Institute of Brooklyn.     

醋酸乙烯酯乳液聚合的研究动态

概述了乳液聚合的发展和应用现状．介绍了有关醋酸乙烯乳液聚合的新方法。     

氯醋树脂中乙烯醇含量的测定方法

本文建立了三元氯醋树脂中乙烯醇含量的化学分析方法,使用乙酸酐在吡啶的存在下对树脂进行酰基化,过量的酸酐水解后用氢氧化钾滴定。方法准确性好,精密度高,相对标准偏差为0.016。同时指出了另一种推算法与直接法有固定偏差,能够快速获得实验结果。     

Study of Vinyl Acetate Partitioning in Emulsion Copolymerization of Vinyl Chloride-Vinyl Acetate by FTIR and HNMR Spectroscopy

Emulsion copolymerization of vinyl chloride with vinyl acetate comonomer was performed. Potassium persulfate, a mixture of stearyl alcohol and sodium lauryl sulfate, was used and reactions were performed at 55 °C in a pressurized reactor. By sampling during the reaction in different intervals copolymer composition was investigated using FTIR and NMR spectroscopy. The results showed that the partitioning of vinyl acetate in the copolymerization in general follows the Mayo-Lewis copolymerization equation with some discrepancy. This was attributed to the gaseous nature of vinyl chloride monomer and the differences between polymerization in heterogeneous and homogeneous systems. Both FTIR and NMR spectroscopy showed two peaks in vinyl acetate content of copolymer beyond 65% conversion which was attributed to the elimination of vinyl chloride droplets in the media and replacing them with vinyl acetate monomer. The first increase is related to the consumption of vinyl chloride droplets and the second is related to the consumption of gaseous vinyl chloride; in both instances vinyl acetate governs the polymerization.     

Influence of catalyst structure on direct ethoxylation of fatty methyl esters over Al-Mg composite oxide catalyst

During direct ethoxylation of fatty methyl ester over Al-Mg composite oxide catalyst, the activity was nearly proportional to the total number of active Al acidic sites on the catalyst surface per unit weight of catalyst. Lower active Al acidic site densities resulted in a narrower ethylene oxide (EO) adduct distribution of obtained ethoxylate. We developed a new catalyst with a large surface area on which many acidic sites are distributed uniformly by partially poisoning the Al acid sites of high-Al content Al-Mg composite oxide with alkali. This catalyst was used for direct ethoxylation of fatty methyl esters to obtain ethoxylated fatty methyl esters with narrow EO adduct distribution efficiently.