New vinyl ester monomers for emulsion polymers

New vinyl ester monomers are now available for the preparation of emulsion copolymers with improved hydrolytic stability and water resistance. These improved properties are the result of uniform copolymerization of hydrophobic monomers having approximately the same reactivity as vinyl acetate. Latex coatings with excellent gloss, water spot resistance, blocking and other desirable performance properties can now be obtained with vinyl acetate copolymers.     

Influence of nonionic emulsifiers on the properties of vinyl acetate/VeoVa10 and vinyl acetate/ethylene emulsions and paints

This paper presents results on the influence of the nonionic surfactant on the properties of vinyl acetate/VeoVa10^® and vinyl acetate/ethylene emulsions and paints made thereof. Emulsions were prepared in which the concentration of the nonionic surfactant and its degree of ethoxylation were varied. An increase of the nonionic emulsifier concentration and of the length of the ethylene oxide chain leads to dispersions with smaller particles and higher viscosities. Using these emulsions as binders in high pigmented paints, it was observed that the pigment binding capacity of the interior paints goes through a maximum which is located at a emulsifier concentration of about 2–3% and at a degree of ethoxylation of 17–28 mol ethylene oxide (EO). In (semi-) gloss paints, the gloss of the paint films improves with an increase of the emulsifier concentration and reaches a constant value at around 4% or a degree of ethoxylation of ca. 17 EO-moieties per molecule. The blocking of the films shows a drastic increase at a concentration above 4% and at a chain length of greater than 17 EO-moieties.     

耐腐蚀性乙烯基酯树脂的研究与应用

论述了乙烯基酯树脂优异的耐腐蚀性能、耐腐蚀原理及目前国内外耐腐蚀性乙烯基酯树脂的研究进展和在一些领城的典型应用。     

Viscoelastic properties of latex paint films in tension: Influence of the inorganic phase and surfactants

The tensile properties of latex coatings were investigated with a set of custom formulated artist-type paints at an age of 1 year. All films in the study contained a poly(methyl methacrylate-cobutyl acrylate) binder exhibiting a glass-transition at approximately 10 °C. The viscoelastic behaviour of the latex matrix is first highlighted through a series of experiments involving different strain histories and temperatures. Influence of the inorganic particle concentration and geometry is then illustrated using TiO₂ and calcined kaolin for the secondary phase. Experimental data from a wide range of conditions are summarised through master curves of secant modulus and failure strains using time–temperature superposition. The results indicate that the latex films behave in a rheologically simple manner and it is possible to predict the response outside of the experimental time-scale. An analysis by similar methods is also given for TiO₂ pigmented films with/without surfactant removed by immersion in water. Differential scanning calorimetry and atomic force microscopy were also used in conjunction with mechanical tests. The combined findings suggest that a fraction of surfactant migrates to the TiO₂ interface during film formation, where it interferes with adhesion of the acrylic matrix.     

Synthesis and characterization of vinyl ester networks containing phthalonitrile moieties

A new styrenic monomer, 4-vinylphenoxyphthalonitrile, was synthesized by nucleophilic aromatic substitution of 4-vinylphenolate onto 4-nitrophthalonitrile. The new monomer was reacted with dimethacrylate-styrene resins (so-called vinyl esters) via free radical copolymerization at 90, then 120 °C with benzoyl peroxide as the initiator to form networks. The networks were further post-cured at 220, 240, or 260 °C for 4 h to convert the last portion of the methacrylates, and to partially cross-link the pendent phthalonitrile groups. A dimethacrylate-styrene network containing 30 wt% of the phthalonitrile-functional monomer exhibited a 70% reduction in peak heat release rate by cone calorimetry measured at an incident heat flux of 50 kW m⁻² relative to control vinyl ester networks. This still remains somewhat higher than peak heat release rates exhibited by brominated vinyl ester networks, but the CO/CO₂ ratio in the smoke is much lower for these non-halogenated materials.     

Effect of functional monomer on the stability and film properties of thermosetting core-shell latexes

Functionalized core-shell latexes were prepared by copolymerization of butyl acrylate and methyl methacrylate with 2-hydroxyethyl methacrylate (HEMA) or methacrylic acid (MAA), which were added during the first or second stages of polymerization, respectively. The HEMA and MAA concentrations were increased while the equivalent ratio of functional groups remained constant. Colloidal stability, particle size, particle size distribution, film properties and morphology were studied as functions of functional monomer content. The upper limit functionality content was limited by the stability of the system during synthesis. A bimodal particle size distribution was observed for high concentrations of functional monomers. Increase in carboxyl and hydroxyl functionalities improved tensile strength and modulus for un-crosslinked films, and generally higher tensile strength, tensile modulus and storage modulus at high temperature were obtained after the functional latexes were crosslinked with a cycloaliphatic diepoxide.     

Copolymerization behavior and properties of dimethacrylate-styrene networks

Dimethacrylate oligomers diluted with styrene (commonly known as vinyl ester resins) are important matrix resins for fiber-reinforced composites used in construction, marine craft, and transportation vehicles. These comonomers react via free radical copolymerization to yield void-free thermosets. The inter-relationships among copolymerization kinetics, physical properties of the networks, and cure temperatures for a 700 g/mol dimethacrylate oligomer with systematically varied styrene concentrations were investigated. FTIR was used to monitor the reactions of the carbon-carbon double bonds of the methacrylate (943 cm⁻¹) and styrene (910 cm⁻¹). Reactivity ratios were determined via a non-linear method at four cure temperatures. The data were analyzed using the integrated form of the copolymerization equation and assuming a terminal reactivity model to predict copolymer compositions throughout the reactions. The results indicated that at early conversion more styrene was incorporated into the networks at lower cure temperatures. The experimental vinyl ester-styrene network compositions agreed well with those predicted by the integrated copolymer equation at early and intermediate conversion. Mechanical properties of dimethacrylate-styrene networks were determined for materials cured at room temperature and at 140 °C. Materials cured at room temperature were tougher and had lower rubbery moduli than those cured at 140 °C.     

The effects of latex coalescence and interfacial crosslinking on the mechanical properties of latex films

The effects of latex coalescence and interfacial crosslinking on the mechanical properties of latex films were extensively investigated by means of several series of model latexes with varying backbone polymer crosslinking density and interfacial crosslinking functional groups. It was found that the tensile strength of crosslinked model latex films increased with increasing gel content (i.e. crosslinking density) of latex backbone polymers up to about 75% and then decreased with further increase in gel, while their elongation at break steadily decreased with increasing gel content. These findings showed that latex particle coalescence was retarded above a gel content of about 75% so that the limited coalescence of latex particles containing gel contents higher than 75% prevented the tensile strength of crosslinked latex films from increasing by further crosslinking the latex backbone polymers. This was contrary to the theory of rubber elasticity that the tensile strength increases with increasing molecular weight and crosslinking density. This limitation was found to be overcome by the interfacial crosslinking among latex particles during film formation and curing. This paper will discuss the effects of both latex backbone polymer and interfacial crosslinking on latex film properties. It will also discuss the development of self-curable latex blends and structured latexes containing co-reactive groups: oxazoline and carboxylic groups.     

Effect of nano-ZnO addition on the silicone-modified alkyd-based waterborne coatings on its mechanical and heat-resistance properties

A silicone-modified alkyd-based waterborne coating was developed using hexamethylmethoxymelamine (HMMM) as crosslinking agent and para-toluene sulphonic acid (p-TSA) as catalyst. The crosslinking ratio for resin and HMMM was fixed to 70:30, based on FTIR and DSC studies. Nano-ZnO particles were added to this system in different concentrations. The coatings with nano-ZnO particles were characterized using FTIR and DSC. The nano-composite coatings were applied on mild steel panels and were cured at 130 °C for 30 min. The coatings were evaluated for their mechanical and heat-resistance properties. They were exposed to 350 °C for 10 min followed by water quenching. The process was repeated for 10 cycles. Heat-resistance property of the coatings was examined by TGA. Also, surface morphological changes were assessed using SEM and optical microscopy. It was found that the heat-resistance and mechanical properties of the coatings improved significantly as a function of nano-ZnO addition.     

Ultraviolet,water, and thermal aging studies of a waterborne polyurethane elastomer-based high reflectivity coating

A waterborne aliphatic polyurethane-based coating was studied for accelerated ultra-violet (UV), water (WT), and thermal (TH) aging for a period of 1000 h. To monitor the coating durability, samples were tested every 200 h. ATR-FTIR spectroscopy was used to monitor the chemical changes occurring during the aging process. UV–vis with integrating sphere was used to track the change in diffused reflectance, while the optical microscope and the scanning white light interferometry (SWLI) were used for surface characterization. FTIR studies of coatings subjected to UV exposure indicated a decrease in functional groups such as CONH, CH, CO, and COC. The appearance of functional groups such as NH is attributed to chain scission of the polyurethane binder in the coating. Investigation of the degradation mechanism in water and thermal aging showed physical effects through water penetration and the mismatch in the coefficient of thermal expansion as the primary causes of degradation. In all aging scenarios, the reduction of reflectivity was largely due to physical defects caused by the different aging mechanisms.     

聚硅氧烷-丙烯酸酯共聚乳液的研究(Ⅱ)

在硅丙种子乳液的基础上进行丙烯酸酯自由基乳液聚合得到硅丙乳液 ,并用红外光谱 ( IR)分析研究硅丙乳液共聚合的基本原理 ,用透射电镜 ( TEM)和示差扫描量热法 ( DSC)揭示聚硅氧烷在聚丙烯酸酯中的分散状态和微观结构。     

Effect of glycidyl methacrylate (GMA) content on thermal and mechanical properties of ternary blend systems based on cardanol-based vinyl ester resin,styrene and glycidyl methacrylate

Cardanol-based vinyl ester resin (CVER) was prepared by reacting indigenously synthesized cardanol-based epoxidized novolac resin (CENR) with methacrylic acid (MA) in the presence of triphenylphosphine as catalyst. Five samples of cardanol-based vinyl ester resin containing styrene and glycidyl methacrylate (GMA), as diluents, in the weight ratios 40:0, 30:10, 20:20, 10:30 and 0:40 were prepared at room temperature. Sharp exotherms were observed in DSC scans in the temperature range of 60–170 °C. The onset temperature (T_onset), peak exothermic temperature (T_p) and completion temperature (T_stop) decreased with increase in GMA content in the ternary blend systems of CVER/styrene/GMA. A broad exotherm was observed after the initial sharp exotherm that was attributed to the etherification reaction. Cured samples were found to be stable up to 205–235 °C and started loosing weight above this temperature. Rapid decomposition was observed in the temperature range of 400–550 °C as evidenced by TGA analysis. Increase of GMA content in ternary blend systems of CVER/styrene/GMA lowered the tensile strength progressively and enhanced the impact strength and elongation-at-break. The cured films of VER containing mixture of styrene and GMA exhibited good gloss and impact resistance. The chemical resistance of cured films of VER containing mixture of styrene and GMA showed good resistance to acids, deionized water, synthetic sea water and mineral turpentine oil.     

Influence of the inorganic phase concentration and geometry on the viscoelastic properties of latex coatings through the glass-transition

The mechanical properties of artists’ acrylic (latex) paint films containing different volume fractions of TiO₂, CaCO₃ and kaolin were measured in uni-axial tension over a broad range of temperatures and crosshead speeds. Young’s modulus results in the glassy region were first compared with several micromechanics theories for particle-filled composites containing elastic phases. It was found that the Mori-Tanaka theory slightly under-predicted the modulus enhancement, while the Lielens approach provided the most accurate results. A nonlinear viscoelastic material model involving a Prony series and the neo-Hookean hyperelastic function was used to represent the tensile data up to relatively small strains of a few percent. From the experimental data, the material model was calibrated and the required parameters were determined. The derived parameters were then used to re-construct relaxation modulus plots, which were compared with the approximations given by Clements and Mas for the viscoelastic Mori-Tanaka theory in the time-domain. It was found that the experimentally observed modulus enhancement was much stronger than the predicted values in the rubbery region. Mechanisms such as constrained polymer at the inorganic particle interface, and the possible formation of a percolation network are discussed.     

A comparative study on water-based coatings prepared in the presence of oligomeric and conventional protective colloids

Poly(vinyl acetate-co-butyl acrylate) latexes were prepared by using semi-continuous emulsion polymerization method in presence of two different protective colloids which were oligomeric N-methylol acrylamide and conventional poly(vinyl alcohol). The effects of these protective colloids on colloidal, surface and film properties of latexes were examined. Poly(vinyl acetate-co-butyl acrylate) synthesized with oligomeric N-methylol acrylamide, which was characterized by FT-IR, NMR and MALDI-TOF MS, was found to have lower viscosity, finer particle size, better latex stability, lower polydispersity, higher T_g and better film forming behavior compared to those synthesized from the poly(vinyl alcohol).     

Rheological and mechanical properties of percolated cyanate ester nanocomposites

The rheological properties and mechanical properties of percolated cyanate ester monomer/layered silicate mixtures are reported. A number of different cation exchanged montmorillonites were examined in an effort to achieve maximal montmorillonite delamination. The dispersion throughout the cyanate ester of a montmorillonite with phenylated ammonium cations (2MBHT MMT) results in the formation of a percolated network. The rheology of this percolated network undergoes a viscous liquid to elastic solid transition at 4 wt% montmorillonite. The percolation of the montmorillonite in the cyanate ester results in a significant improvement in crack resistance (80%) without a sacrifice of flexural strength.     

淀粉酯的合成、性质及应用

由于淀粉的可再生性和可应用性现已受到人们的广泛关注。通过酯化过程对淀粉改性,使淀粉的性质发生改变,扩大了淀粉的应用领域。文章对琥珀酸淀粉酯、醋酸淀粉酯、柠檬酸淀粉酯、长链脂肪酸淀粉酯、磷酸淀粉酯、硫酸淀粉酯的合成、性质及应用进行了综述,并对其发展前景进行展望。     

Effects of morphology and surface treatment of inorganic pigments on waterborne coating properties

Inorganic pigments in aqueous coatings are investigated using atomic force microscopy and microprobe analysers. The first method characterises the topography at a very high resolution. The findings obtained using the second method reveal the distribution of the pigment in the paint film. Taking selected titanium dioxide and iron oxide pigments, the effects of particle morphology as well as inorganic and organic surface treatment on the dispersibility and flocculation stability are shown. These two phenomena are factors in gloss, hazing, hiding power, tinting strength and viscosity – key quality parameters in waterborne coatings.     

Synthesis and properties of alkoxysilane-functionalized styrenated oil based polyester

Alkoxysilane-functionalized styrenated oil based polyester hybrid films were prepared by using vinyl trimethoxysilane (VTMS) as an inorganic source. For this purpose, an oil based polyester (PGMA) was first synthesized by the esterification of partial glyceride (PG) mixture with maleic anhydride (MA). Then, PGMA was further reacted with both styrene (St) and the mixture of St and VTMS yielding St–PGMA and St–PGMA–VTMS samples, respectively. The synthesis was carried out by changing VTMS content in the range of 5–15 wt.% in order to investigate the effect of inorganic domains on the film properties. While the films of St–PGMA–VTMS were formed on the appropriate substrates by moisture curing and oxidative polymerization, St–PGMA films were only cured by oxidative polymerization. The characterization of the polymers was done by FTIR, ¹H NMR, DSC, TGA and SEM. FTIR and DSC analyses indicated the completion of the moisture curing process. Film properties such as flexibility, adhesion, water, alkali and acid resistances were determined. All samples showed good film properties. Moreover, in comparison, St–PGMA–VTMS samples exhibited better alkali resistance than St–PGMA due to the contribution of the inorganic domains.     

Synthesis and characterization of waterborne polyurethane emulsions based on poly(butylene itaconate) ester

Waterborne polyurethane (WPU) prepolymer was synthesised by the reaction of poly(butylene itaconate) ester (PBI, Mn = 1109 g/mol), 1,6-hexanediol, dimethylol propionic acid (DMPA), 2,4-toluene diisocynate (TDI), hydroxyethyl acrylate (HEA), and absolute ethanol as blocking agent, triethylamine as neutralizer. Cross-linked WPU was synthesized by trimethylolpropane (TMP) as crosslinker. The influences of PBI, DMPA, and TMP content on WPU emulsions and films were investigated. The structure of WPU was determined by Fourier transform infrared (FTIR) spectra, thermal properties and glass transition temperature of WPU films were determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively, and morphology of the emulsion particles was observed by transmission electron microscopy (TEM). Through TGA, the heat resistance of the cross-linked WPU film was better than WPU film. By DSC analysis, glass transition temperature of cross-linked WPU film (21 °C) was higher than WPU film (10 °C).     

马来海松酸新戊二醇酯多元醇的制备及性能

马来海松酸酐(MPA)具有良好的耐热性能,被用作制备耐热多元醇的原料而得到广泛研究.实验将含有耐热基团的新戊二醇(NPG)和MPA制备多元醇酯,以进一步提高产品的耐热性能.研究了反应体系的酸值变化,通过改变NPG与MPA的摩尔比,得到了具有较大羟值范围的系列产品.对产品进行了红外和热重表征.结果表明,MPA的三个羧基均发生了酯化反应,且反应较为彻底.酯化产物具有较高的初始失重温度,可作为耐热原料使用.