Cured polyester resin

Structures present in cured polyester resin. Cross-linking via an addition copolymerisation reaction. The value of n 2-3 on average in general purpose resins... 

J.W. Cywinski, The Role of Organic Peroxides in Curing Polyester Resins and Their Influence on The Physical Properties of Re-... 

Phenanthroline and some of its alkyl-substituted derivatives improve the heat stability of polyesters594 and magnetic recording tape.595 They also improve the color of cured polyester resins.596 They are also useful in various electroplating and electrolytic processes597-601... 

The chemical structure of glycols influences the tensile and flexural properties of cured polyester resins. Glycols with more carbon atoms generally... 

Han and Lem (1983) reviewed the cure kinetics, chemorheology and properties of curing polyester resins. 

Cadox . [Akzo] Organic peroxide compds. initiator to curing polyester resins crosslinking agent to curing silicone rubbers. 

Luddol. [Atochem N. Am.] Benzoyl pooxide initiator for polymerization, curing polyester resins, elastomers, aaylics. 

Quickseti. [Wiico/Aigns] MEKpercn-ide initiator for curing polyester resin. 

Very little is known about the structure of the cured polyester resin. The products definitely belong in the thermoset class. There is some correlation between maximum physical properties a nd a molar ratio of 1 1 between double bonds in the alkyd and monomer. However, this is not critical and simple cross-linking does not tell the full story. The styrene monomer can be present in twice the molar amount needed, and yet complete copolymerization takes place without apparent formation of styrene polymer. 

The saturated acid (phthalic anhydride) helps to reduce the cross-link density and, hence, the brittleness of the cured polyester resin. Resin composition can be varied so that product properties can be tailored to meet specific end-use requirements. For example, a resin with enhanced reactivity and improved stiffness at high temperatures is obtained by increasing the proportion of unsaturated acid. On the other hand, a less reactive resin with reduced stiffness is obtained with a higher proportion of the saturated acid. 

FIGURE 4.12 Curing of unsaturated polyesters, (a) Species in polyester resin ready for laminating, (b) Structures present in cured polyester resin. Cross-linking takes place via an addition copolymerization reaction. The value of n 2-3 on average in general-purpose resins. (After Brydson, J. A. 1982. Plastics Materials. Butterworth Scientific, London, UK.)... 

Polyester resins are cured by organic peroxides that initiate a free radical copolymerization reaction. This can occur at room temperature, under heat [60-90C (140-194F) or by UV or visible light radiation. The possibility of cold-curing polyester resins from the liquid state is one of... 

Cured polyester resin is not subject to fungal attack, but when the surface has eroded sufficiently, it will trap spores carried in the air which may grow and become unsightly. These can be removed by cleaning. Polishing or the application of a surface coating will delay their reappearance. 

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. 

Consider now the effect of surfactant on the properties of the initial and the cured polyester resins. Such systems show a ninnber of particular features. The structme and properties of the cured polyester resins are determined to a great extent by the compatibility of the copolymerizing components of the system. There is almost no information on the possibility of controlling this compatibility by means of surfactant, which is why it is of great interest to study the influence of surfactant upon the thermodynamics of compatibility of the components of the cured polyester resin, as well as the effect of this compatibility on the molecular mobility of the polymeric chains and on the physical-mechanical properties of the polymer. 

The molecular mobility in the polymers was determined by dielectric studies. Polymer films 300—500 pm thick cast between glass plates at room temperature were used. Dielectric measiu ements were made using the E8-4 ac bridge within a broad temperature range. The superimposed frequency of the external electric field was 1 kHz. The dependence of the coefficient of transmission of the cured polyester resin on the OP-10 content was determined using the FEC-56M photoelectric calorimeter. 

As Fig. 2.17 (curve 2) shows, the strength of the cured polyester resin containing OP-10 has a maximum within the area of 5% of surfactant that corresponds to the minimum value of X2,s (Fig- 2.18, curve 2) and to the highest temperature at which the maximum of tan 6 appears (Fig. 2.17, curve 1). This is confirmed by studies of the turbidity of the cured polyester resin containing OP-10. The transmission... 

The influence of surfactants on the formation of microdiscontinuities. The structure and properties of the cured polyester resin are determined to a great extent by the compatibilily of the system s copolymerizing components. Let us therefore consider the possibility of regulating their compatibility with the help of surfactants. 

Properties Liq. m.w. 208.33 dec. 180 C Uses Crosslinking agent for elastomers, resins initiator for curing polyester resins finishing initiator for styrenics a synergist for some halogen-containing flame retardants polymer modifier... 

Table 2.28 Typical properties of cured polyester resins...

Curing polyester resins involves the transformation of the polyester from a liquid to a solid state, taking place on the addition of a catalyst, usually organic peroxide (Table 13.2). To speed up the process, the catalyst has to be activated, either by heating or, by the addition of an accelerator. The crosslinking reaction is exothermic and, since polyester resins are... 

Elf Atochem, Paris, France— manufacture organic peroxides for curing polyester resins. 

Naphthenic acid n, A carboxylic acid derived from petroleum refining and usually one of a mixture of similar compounds. The mixed acids and some of their soaps, e.g., cobalt naphthenate and calcium naphthenate, are useful as catalysts or accelerators in curing polyester resins and as drying agents in paints and varnishes. Commercial naphthenic acids are not pure compounds, but consist of a mixture of acids based on cyclopentane rings. 

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