Swelling polyester resin

Cyclic oligomeric phosphonates with the varying degrees of structural complexity (Structure 5.4) are also available in the market.25 They are widely used as flame-retardant finishes for polyester fabrics. After the phosphonate is applied from an aqueous solution, the fabric is heated to swell and soften the fibers, thus allowing the phosphonate to be absorbed and strongly held. It is also a useful retardant in polyester resins, polyurethanes, polycarbonates, polyamide-6, and in textile back coatings. A bicyclic pentaerythritol phosphate has been more recently introduced into the market for use in thermosets as well as for polyolefins (preferably, in combination with melamine or ammonium polyphosphate)... 

Bubject to wear on pumps, agitators, etc. In dilute solutions, wood is aatisfactory where conditions allow it to swell and seal pores, cracks, etc. Care must be taken that hoops, tie rods, etc., are coated with an inert material such as tar, pitch, silicates, epoxy and polyester resins, polyvinyl chloride, etc. For hydrochloric acid, rubber-lined steel is excellent at low... 

Internal disk cracking (blistering) in resins was first reported by Steel [42] in 1967, and attributed to swelling, followed by rupture due to hydrolytic attack on the strained polymer chain. Ashbee et aL [43] found that fully cured polyester resins developed disk -shaped internal cracks when exposed to hot water and proposed an osmosis hypothesis for blister formation. 

Solvents used for paint removal are able to dissolve or considerably swell physically drying binders (e.g., vinyl chloride copolymers, cellulose nitrate, polyacrylates) and chemically cross-linked coatings (e.g., oil-based paints, dried alkyd resins, cross-linked polyester-melamine resins, cross-linked epoxy and isocyanate coatings) [14.237]. A combination of dichloromethane with low-boiling ketones or esters is particularly suitable. Small amounts of high-boiling solvents with a low volatility (e.g., tetrahydronaphthalene, solvent naphtha, methyl benzyl alcohol, or benzyl alcohol) are added to these mixtures to retard evaporation and increase the solvency. Modern paint removers do not contain chlorinated hydrocarbons, they are formulated on the basis of high boilers (e.g., dimethylformamide, dimethyl sulfoxide, propylene carbonate, and yV-methylpyrrolidone) in combination with alcohols and aromatics, or consist of aqueous, frequently alkaline or acidic systems. 

Organic compounds with carbon-carbon unsaturated double bonds, such as carbon disulfide, are powerful swelling solvents and show greater swelling action than their saturated counterparts. Smaller solvent molecules can penetrate a polymer matrix more effectively. The degree of similarity between solvent and resin is important. Slightly polar resins, such as polyesters and the vinyl esters, are attacked by mildly polar solvents. 

FIGURE A3.38 Swelling behaviour of a polyester casting resin (Polymaster Warwick). Contours are shown at 50% (—) and 100% (—) swelling in solvent. 

Water permeation, for instance, can lead to problems of dimensional change due to swelling of the polymer matrix as well as to chemical alternations within the composite. For instance, whilst epoxy resins are generally stable to hydrolysis, the ester groups present in polyesters are prone to hydrolysis. ... 

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