Polymer resin unsaturation, determination

Performance Characteristics Polyester resins undergo a rapid transformation from a viscous Hquid to a soHd plastic state that comprises a three-dimensional cross-linked polymer stmcture. The level of polyester polymer unsaturation determines essential performance characteristics (Table 7), although polymer components can influence subtle features that affect thermal, electrical, and mechanical performance as defined by ASTM procedures. 

Furthermore, being a delicate process, the outcome of which determines the properties of resists formulated with rubbers made with it, cyclization procedures tend to be proprietary to the various manufacturers, who take great care to characterize it. The principal criteria they use include the degree of unsaturation and cyclicity (whether the structure has monocyclic, bicyclic, or tricyclic motifs in the polymer). The double bonds can be located inside (endo) or outside (exo) of the rings. The ratio of endocyclic to exocyclic double bonds has some effect on the physical properties of the resin. °... 

A. Spyros, Quantitative determination of the distribution of free hydroxylic and carboxylic groups in unsaturated polyester and alkyd resins by P-NMR spectroscopy,/AppZ Polym Sci, 2002,83,1635 2. 

True properties are determined by the polymer and compound formulation and, for synthetic rubbers, additionally by type of curing agents such as sulfur or peroxides and the state of vulcanization. Typical properties for four polymers often used in automotive applications [acetals, nylons, polycarbonates, and unsaturated polyester (vinyl esters)] are shown in Tables 10.1 through 10.4. Typical property data is readily available from resin producers and compounders. Property data for elastomers is found in the chapter on elastomers in this handbook. 

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