Epoxy-containing polyesters

Scheme 4.10 Enzyme-catalyzed synthesis of epoxy-containing polyester.

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

For this use, the preferred powders are based on acrylic, epoxy or polyester and epoxy resins. For best colour, epoxy resins are crosslinked with anhydrides of dicarboxylic acids in the straight epoxy coatings, or with saturated polyesters of high acid content in the epoxy-polyester type. Acrylics contain epoxide rings via, for example, glycidyl methacrylate (CH2=C(CH3) —CO—O—CHj—CH —CH2), and these groups crosslink... 

Siloxane containing polyester, poly(alkylene oxide) and polystyrene type copolymers have been used to improve the heat resistance, lubricity and flow properties of epoxy resin powder coatings 43). Thermally stable polyester-polysiloxane segmented copolymers have been shown to improve the flow, antifriction properties and scratch resistance of acrylic based auto repair lacquers 408). Organohydroxy-terminated siloxanes are also effective internal mold release agents in polyurethane reaction injection molding processes 409). 

Although polyurethanes or other reactive resins can be used in RTM, the most common resins are polyesters and epoxies. The two pumping reservoirs in Figure 7.90, then, contain polyester resin and initiator, or epoxy resin and hardener, respectively. Epoxies require relatively long cycle times. When cycle time is critical, low viscosity vinyl ester, acrylamate, or urethanes can be injected very rapidly into the mold. Even the use of thermoplastics is possible. 

The response of films containing polyester plasticizers or the trialkyl phosphate to the arsine-epoxy adduct was noteworthy and, to the degree obtained, unexpected. 

In the TEM samples, the rubber domains are uniformly distributed and on the order of a few hundred angstroms in size. The micrographs also show the presence of domains that have no rubber in them. The rubber-free domains probably contain polyester and epoxy that have reacted, but it is not possible to confirm this possibility. Styrene-cross-linked polyester has a Tg of 185 °C. When the epoxy is introduced in a 1 2 ratio (epoxy-.polyester), Tg de-... 

There are two basic VPI resin formulations. One is based on epoxy resins, and the other is based on unsaturated polyesters. Both are typically one-part solventless compositions that are completely polymerizable. Volatile, nonpolymerizable solvents cannot be tolerated because these will lead to bubbling in the vacuum impregnation procedure. To control viscosity of the resin formulations, the epoxies contain low-viscosity, reactive diluents of the monoglycidyl ether type the unsaturated polyester formulations contain styrene or vinyltoluene as reactive diluents. Both resin types contain catalysts that become active only at elevated temperatures to insure long-term stability at room temperature. The epoxy resins are frequently catalyzed with metal organic compounds such as titanium complexes, and peroxides are usually the main catalyst in the unsaturated polyester formulations. In addition to the ingredients mentioned here, the compositions may contain additives such as cocatalysts, activators, and accelerators. However, there are no particular fillers used in VPI resins. 

Thermosetting polymers, like phenolics, epoxies, unsaturated polyesters, etc, are frequently used in formulations containing a low or high-molar-mass rubber, a thermoplastic polymer, an oil, etc, in an amount of the order of 2-50 wt% with respect to the thermoset. This extra component, called the modifier, may initially be immiscible or may phase-separate during cure (reaction-induced phase separation). 

Uses Solvent in coil, container, and automotive coatings, printing inks, acrylic lacquers, enamels, surf, primers for epoxies and polyesters, paint strippers, foundry core binders, resin cleanup, intermediates, industrial cleaners, wire enamel resins Features Offers VOC compliance, noncorrosive Regulatory DOT nonregulated SARA 302, 313 nonreportable Properties APHA 50 max. sweet odor sol. in alcohols, esters, glycol ethers, halogenated soivs., ketones, hydrocarbons sol. 5.5% in water m.w. 160 sp.gr. 1.086 dens. 9.06 Ib/gal vise. 3.88 cps f.p. -40.2 C b.p. 200-220 C acid no. 0.1 flash pt. (PMCC) 102 C surf. tens. 35.4 dynes/ cm 0.1% max. water content... 

When the solvent requirement of the container wash plant and the customers s spent solvent quantities were added together, the total was about 200 toimes of contaminated solvents per year. Solvents such as toluene, ketones, esters, ethyl acetate, xylene, glycol and petroleum spirits were to be separated almost completely from solids such as alkyd, 2-pack, epoxy and polyester resins. 

These hyperbranched resins showed excellent adhesion, gloss, flexibility, and formability. The viscosities of epoxy functionalised polyester based coating mixtures with vernolic acid were also heavily influenced by the presence of the reactive diluent, from pure hyperbranched epoxy functionalised polymer with a viscosity of 4100 mPa s, to a formulation containing 30 wt% methyl ester of vernolic acid with a viscosity of 460 mPa... 

As structural adhesives, epoxies are the most widely accepted and used. They typically contain several components, the most important being the resin. To the base resin is added a variety of materials, for example hardeners, flexibilisers, tougheners and fillers. These all contribute to the properties of the resulting adhesive. Formulations may be further varied to allow for curing at either ambient or elevated temperatures. The epoxies and polyesters, together with acrylics, polyurethanes and synthetic polymer lattices will be... 

Thermoset materials are produced by the direct formation of network polymers from monomers, or by crosslinking linear prepolymers. Important thermosets include alkyds, amino and phenolic resins, epoxies, unsaturated polyesters and polyurethanes. Thermosetting polymers consist of two liquid components, one containing a resin and the other a hardener [1]. 

Urethanes are reaction products of isocyanates with materials possessing hydroxyl groups. The polyol side may consist of a number of hydroxyl-containing materials, including water, as well as epoxies, polyesters, acrylics, and drying oils. Epoxy and polyester polyols are more chemically and moisture-resistant than acrylic polyols. They are also more expensive. 

Structural reaction injection molding (SRIM) is usually used to produce stiff composites containing polyester or epoxy matrices. In such techniques, the mold consists of a cavity which can be subjected to vacuum. The fiber reinforcement structure in the form of mats or fabrics is placed into this cavity prior to applying vacuum, followed by injecting the two-component polymer. Vacuum, sometimes in combination with pressure, is used to introduce the polymer into the mold cavity and to force it to penetrate the fiber reinforcement structure and form the polymer matrix. For elastomer composite formation, this molding concept is new. The mold development was made because of the higher viscosity in typical two-component elastomers compared to normal polyester- or epoxy-based rigid matrix polymers. 

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