Sucrose octaesters as reactive diluents for alkyd coatings

Sucrose octasoyate (SS8) was investigated as a reactive diluent for a medium oil alkyd (MOA). SS8, which is derived from sugar and soybean oil, is 100% biobased, nontoxic, and biodegradable. As a result of its unique molecular architecture, it was expected that SS8 would be an excellent reactive diluent for alkyd coatings. The experiment conducted basically involved the incremental replacement of the MOA with SS8, while maintaining essentially equivalent solution viscosity. The properties of cured coatings were determined using industry standard methods. In general, it was found that SS8 could be used to reduce volatile organic compound content of the coatings, while also reducing drying time (i.e., tack-free time), increasing solvent resistance, and increasing impact resistance. Of the properties measured, the only cured film property that was negatively affected by the use of SS8 was the König pendulum hardness. However, the reduction in König pendulum hardness was only observed when the amount of MOA replaced by SS8 was greater than 10 wt%. Overall, these initial results suggest that SS8 is a very good reactive diluent for alkyd coatings.     

Synthesis and curing of rod-like epoxies with alkoxy groups as flexible side chain

Summary A series of aromatic diepoxides consisting of rigid ester unit with different lengths of flexible alkoxy side groups (R = H, OCH₃, OC₃H₇, and OC₈H₁₇) were synthesized, and their thermal and cure behavior with aromatic diamine were investigated by using a DSC. The values of melting temperatures for the epoxy monomers ranged from 65 to 221°C depending upon the length of side groups. Cure kinetics of an epoxy/4,4′-diaminodiphenylmethane (DDM) system with two different side groups (R = OC₃H₇ and OC₈H₁₇) forming homogeneous mixture was examined using a multi-temperature scan method, developed by Ozawa and Kissinger, in order to determine the activation energy (E) and the frequency factor (A). The epoxy monomer having longer side group showed smaller E and larger A, indicating that the introduction of the long flexible side group could accelerate the cure reaction of rod-like epoxy. Received: 15 January 2002 / Accepted: 4 March 2002     

Study on the curing reaction,dielectric and thermal performances of epoxy impregnating resin with reactive silicon compounds as new diluents

Two silicon compounds including (3‐glycidoxypropyl)trimethoxysilane (A187) and (3‐glycidoxypropyl)methyldiethoxysilane (W78) were used and studied as reactive diluents for aluminum (III) acetylacetonate (Alacac) accelerated epoxy/anhydride impregnating resin systems. The dielectric performances were studied and characterized by the dielectric dissipation factor, dielectric constant, volume resistivity, and breakdown strength. The curing behaviors and thermal properties of the cured impregnants were studied by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetry. The activation energies of different epoxy formulations were determined with Kissinger method. The results showed that W78 was effective to decrease the viscosity and had little influence on the curing reaction. The cured sample of 15 parts‐of‐W78‐containing‐epoxy resin/methyl‐hexahydrophthalic anhydride (MHHPA) accelerated by Alacac exhibits good dielectric and heat resistant performances with a dielectric dissipation factor below 0.04 at 155°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A model study on fatty acid methyl esters as reactive diluents in thermally cured coil coating systems

A model study on the transesterification reaction between fatty acid methyl ester (FAME), e.g. methyl oleate, methyl linoleate, rape seed methyl ester and different alcohols in thin films have been performed. The purpose was to evaluate the possibility to use fatty acid methyl ester (FAME) as reactive diluent in thermally cured coil coating paints. A reactive diluent must be compatible, act as a diluent, react into the film without affecting the end properties. The transesterification between the methyl ester and hydroxyl functional model compounds was monitored by ¹H NMR and real time IR. The effects addressed in the present study were compatibility, temperature, catalyst, alcohol structure, and fatty acid methyl ester (FAME) structure. Competing factors with the transesterification reaction were shown to be evaporation and side reactions, i.e. oxidation. The structure of the fatty acid methyl ester (FAME) affects the conversion as a higher amount of unsaturations triggers the competing side reaction oxidation. The reaction time and temperature affects both the degree of transesterification conversion, degree of side reactions and the catalyst choice. The present study has shown that a fatty acid methyl ester (FAME) fulfils the reactivity part for a reactive diluent in a thermally cured coating system.     

Curing studies on vinyl ester resin using acrylates as reactive diluents

The curing behavior of bis(methacryloxy) derivatives of diglycidyl ether of bisphenol A (vinyl ester resin) containing acrylates (methyl, ethyl and butyl acrylate) as the reactive diluents (40% w/w) were studied by DSC analysis. Data found in this study indicated that an appreciable curing rate is obtained at lower temperature with increased concentrations of initiator. The acid value, activation energy, Arrhenius factor and specific heat are discussed.     

Thermochemistry of model curing reactions of epoxy resins

Summary The heats of reaction of phenylglycidyl ether and N,N-methylglycidylaniline as model systems for two different types of epoxy resins with primary and secondary amine were determined. In all cases the heat of reaction was found to be dependent on the ratio of the reactant components. This dependence is probably due to the formation of various complexes via a hydrogen bond. It was also found that, while the heats of reaction of phenylglycidyl ether with primary and secondary amine are the same, the heats of reaction of N,N-methylglycidylaniline with primary and secondary amine differ significantly from each other.On leave of absence from the Research Institute of Synthetic Resins and Lacquers, PardubiceThe authors thank Dr .tokrová, Dr S.Pokorný and Dr .Podzimek, Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, Prague, for the analysis of the reaction products.     

Modeling coupled migration and settling of particulates in curing filled epoxies

Epoxy resins filled to a high solids loading (40–60% by volume) with noncolloidal particles are used to mitigate stress and vibration in electronic components. We perform continuum‐level finite element method (Schunk et al., A Full‐Newton Finite Element Program for Free and Moving Boundary Problems with Coupled Fluid/Solid Momentum, Energy, Mass, and Chemical Species Transport: User's Guide, Sandia National Laboratories) simulations of filler particle redistribution during the nonisothermal cure of the epoxy under both quiescent and bulk flow conditions. An extent of reaction is used to track the degree of cure. To determine the particle migration, we couple a diffusive flux suspension model (Zhang and Acrivos, Int J Multiphase Flow 1994, 20, 579.) with the curing model. The heat transfer, including the exothermic polymerization reaction, is also modeled. The result is a generalized Newtonian model that has viscosity as a function of temperature, cure and particle volume fraction. With x‐ray computed tomography, we examine settling of the particulate phase in both flowing and quiescent curing systems and compare the experimental results to the model predictions. The model is also validated with temperature measurements. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Chemoenzymatic synthesis of oil-modified acrylic monomers as reactive diluents for high solids coatings

Over the past few decades high solids coating has gained widespread acceptance in industry due to improved performance, reduction in cost and the meeting of VOC regulations. One attractive approach for achieving high solids coating is through the use of a reactive diluent in the system. In the present study, the chemoenzymatic synthesis of oil-modified acrylic monomers has been reported. The diglyceride separated by column chromatography from partial esters synthesized by lipase-catalyzed transesterification of soybean and linseed oil with n-butanol (Step I) was further subjected to acryloylation or methacryloylation to yield oil-modified acrylate or methacrylate monomer, respectively. The newly synthesized monomers were characterized by IR, ¹H NMR, solubility, resin compatibility and their evaluation as reactive diluents in high solids coating compositions.     

Syntheses of allyl phenyl acrylates and their evaluation as reactive diluents in UV-curable coating compositions

para-Substituted 2-allyl phenyl acrylates, and diallyl, dipropenyl and dipropyz bisphenol-A diacrylates have been synthesised in high yield and purity and characterised by spectroscopic methods. UV-curable coating compositions have been formulated using these monomers as reactive diluents. Their film properties were studied.     

Effect of diluents on the curing behavior of vinyl ester resin

An acidic vinyl ester resin (～6 mg KOH per gram of solid) was prepared by reacting a bisphenol‐A‐based epoxy resin with acrylic acid in the presence of tributyl amine. The acrylated epoxy resin thus obtained was characterized by Fourier transform infrared spectroscopy. Five samples of vinyl ester resin containing styrene and methyl methacrylate (MMA) in the weight ratios 40:0, 30:10, 20:20, 10:30, and 0:40 were prepared at 30°C, and their curing behavior was studied by differential scanning calorimetry in the presence of benzoyl peroxide (2 phr). Curing behavior was dependent on the ratio of the two monomers used as reactive diluents. The kinetic parameters were determined by Ozawa's method. The energy of activation and frequency factor varied from 17 to 23 kcal mol^?1 and 8.47 × 10⁹ to 5.21 × 10¹² min^?1, respectively and were lowest for the samples containing 30:10 and 10:30 styrene/MMA weight ratios. The curing reactions followed first‐order kinetics and obeyed the Arrhenius rate expression. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1948–1951, 2003     

A kinetic model for curing reactions of epoxides with amines

Curing reactions of epoxy resins are accelerated by added hydrogen-bond donor solvent and hydroxyl groups produced during the course of polymerization. A kinetic model comprising several different polycondensation and polyaddition reactions that occur simultaneously is developed. The concept of diffusion controlled reactions is employed to describe the change of reaction rate constants with conversion after the formation of an infinite crosslinking network. Good agreement is obtained between the model predictions and experimental data available in the literature.     

Non-isothermal curing of reactive plastics

One dimensional transient heat conduction analysis of reactive, unfilled polyesters and epoxies shows that care must be taken during curing to minimize large temperature excursions due to internal heat generation. Isothermal heat generation rates have been shown to underestimate the non-isothermal values by more than an order of magnitude.     

Crosslinking of epoxidized natural oils with diepoxy reactive diluents

The different natural oils epoxidized with 3‐chloroperbenzoic acid were crosslinked with diepoxy reactive diluents, bisphenol A propoxylate diglycidyl ether, and 3,4‐epoxycyclohexylmethyl‐3,4‐epoxyclohexane‐carboxylate, using cationic initiator at 60°C and photoinitiators at the room temperature. The insoluble fraction of the polymeric products was 59–90%. The Young modulus of the crosslinked polymer films ranged from 2 to 861 MPa. The 10% weight loss temperatures of the crosslinked polymers estimated by thermogravimetric analysis were in the range from 250 to 420°C. The water vapor transmission rate of the crosslinked biopolymer films ranged from 6 to 49 g/m²/24 h. Biochemical oxygen demand and biodegradation in soil of the crosslinked polymers were studied. The crosslinked polymers showed higher biodegradation rate than cellulose, starch, and polyvinylalcohol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of reactive diluents on mechanical and physical properties of a UV curable acrylated urethane prepolymer

In this study, the dependence of the mechanical properties of a UV curable acrylated urethane on reactive diluent types and their amounts was investigated. The acrylated urethane prepolymer was synthesized from isophorone diisocyanate (IPDI), an aliphatic diisocyanate, and polypropylene glycol monomethacrylate (PPGMMA) by stepwise addition reaction. UV sensitive mixtures containing N-vinylpyrrolidinone (NVP), thiodiethylene glycol diacrylate (TDGDA) and isobornyl acrylate (IBoA) as reactive diluents were irradiated by UV light. An increase in reactive diluent content, either TDGDA or IBoA, caused an increase in tensile strength and a decrease in elongation values. In contrast, above a certain concentration a decrease in tensil strength was observed when NVP was used as reactive diluent. The water absorption capacities of the UV curable acrylated urethane films were observed to depend on type and amount of reactive diluent that was used. Thermooxidative properties of the films were also improved by incorporation of reactive diluents into formulations.     

Crosslink mechanisms of high-solids alkyd resins in the presence of reactive diluents

The drying of alkyds was studied using NMR and mass spectrometry employing model compounds. Crosslinking occurs via oxidation of unsaturated fatty (linoleic) acids in the resin. Hydroperoxides formed as intermediates are degraded to alkoxy and peroxy radicals by cobalt catalyst. These radicals then recombine to form mainly ether and peroxy crosslinks. However, with conjugated fatty acids another mechanism prevails in which addition of radicals to the double bonds occurs. Despite the differences in mechanism the rates of both reactions were found to be similar. High-solids alkyd coatings may employ reactive diluents replacing traditional solvents (white spirit). The rate of incorporation of these reactive diluents into the actual paint film during drying can be followed with NMR. Allyl ether groups appear to react fastest whereas allyl esters show generally little reactivity. Using mass spectrometry it was found that incorporation involves recombination of radicals as well. However, reactive diluents with conjugated double bonds will be incorporated by radical addition.     

Dynamic mechanical properties of UV-curable polyurethane acrylate with various reactive diluents

UV-curable polyurethane acrylate (PUA) based on polycaprolactone and m-tetramethylxylene diisocyanate were considered with different acrylate monomers as reactive diluents: ethylhexylacrylate, hexanediol diacrylate, and isobornyl acrylate. The effect of the chemical structure and functionality of the reactive diluent (33 wt %) on their thermal and mechanical properties were investigated. The synthetized PUA networks are homogeneous from a thermodynamical point of view. The initial glass transition temperature (T_g) and the functionality of the reactive diluent do not affect the onset value of the glass transition temperature of the network. Nevertheless, the main mechanical relaxation, denoted α, associated with the glass transition temperature becomes broader as the T_g of the homopolymer of the considered reactive diluent becomes higher than the T_g of the PU soft segments. The increase of the amount of the diacrylate monomer leads to an increase in the equilibrium and storage moduli in the rubbery state and to a decrease in the amplitude of the α relaxation. © 1996 John Wiley & Sons, Inc.     

Properties and curing behavior of reactive blended allyl novolak with bismaleimide using dicumyl peroxide as a novel curing agent

For reducing the cure temperature and improving the thermal stability and mechanical properties, a thermosetting resin system composed of novolak and bismaleimide (BMI) was developed by reactive blending and using dicumyl peroxide (DCP) as a novel curing agent. Novolak was allylated and reacted with BMI to produce bismaleimide allylated novolak (BAN), and the effect of DCP on flexural, impact and heat distortion temperature of cured resin were investigated. On the basis of improved mechanical and thermal properties at 0.5% DCP contents, the curing behavior of DCP/BAN resin system was evaluated by DSC analysis. Ene, Diels‐Alder, homo‐polymerization and alternating copolymerization which occurred in DCP/BAN resin system were further verified using FTIR at sequential cure conditions from 140 to 200°C. Kissinger and Ozawa‐Flynn‐wall methods were used to optimize the process and curing reactions of DCP/BAN resin system. The results showed that the addition of 0.5% DCP in BAN reduced the curing temperature and time of the modified resin. For evaluating process ability of the modified system, composite samples using polyvinyl acetyl fiber were molded and tested for flexural properties. The resulting samples showed better flexural properties when compared with the composite made with neat BAN. The modified 0.5% DCP/BAN resin system with good mechanical properties and manufacturability can be used for making bulk molding compounds and fiber reinforced composites required in various commercial and aerospace applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41829.