Conjugated and other unsaturated polymers

CLASS Conjugated and other unsaturated polymers STRUCTURE ds-Polyacetvlene H H H H... 

Composite matrix resin Conjugated and other unsaturated polymers Polyacetylene Polyaniline... 

Air-drying oils or polyester resins (single component) Conjugated double bonds and other unsaturation sites Air oxidation, peroxide formation, and coupling between polymer chains (free radical) 5 > z D O 70 C 00 m 70... 

Where still more heat resistance is needed, we now have the polyimides, polybenzimidazole polyquinoxalines and other linear polymers in which the methylene content is reduced or eliminated. Conjugated unsaturation increases the thermal stability of these materials. Unfortunately, as the extent of condensation approaches that of the ladder polymer pyr-rones which might provide optimum heat resistance, the polymers become more intractable. 

Conjugated diene polymers are modified and improved by copolymerizing them with other unsaturated compounds, such as acrylonitrile, H2C==CH—C=N. 

Cyclization reactions of natural rubber and other polymers from conjugated dienes have been known for a long time. The reactions occur in the presence of Lewis and strong protonic acids. They result in loss of elastomeric properties and some unsaturation. Carbon cations form in the intermediate step and subsequent formation of polycyclic structures ... 

Structural changes in the polymer, which will accompany the formation of small molecule products from the polymer, or may be produced by other reactions, can cause significant changes to the material properties. Development of colour, e.g. in polyacrylonitrile by ladder formation, and in poly(vinyl chloride) through conjugated unsaturation, is a common form of degradation. 

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