Meaning
Unsaturated hydrocarbon compounds containing two double bonds separated by a single covalent bond represent the chemical group used as precursors for synthetic elastomer synthesis. In polymer sourcing, conjugated dienes provide the flexible segments in impact-modified resins like acrylonitrile butadiene styrene. High concentrations of these compounds can lead to gel formation during storage or polymerization, which clogs filters and causes surface defects in molded components.
They must be monitored in feedstock streams to ensure uniform polymerization kinetics.
Chemical Structure
Alternating double and single bonds create a delocalized pi-electron system that imparts high reactivity to these molecules. In the case of conjugated dienes, this structural arrangement allows them to undergo addition polymerization readily. This reactivity makes them vulnerable to oxidation, which generates peroxides that initiate unwanted pre-polymerization.
Storage vessels often require active inhibitor addition to prevent this degradation.
Polymerisation Effect
Elastomeric properties in the final polymer matrix depend on the specific addition pathway during the reaction. The polymerisation effect of conjugated dienes allows them to build synthetic rubbers that absorb impact energy. When these rubber domains are dispersed in a rigid matrix, they arrest crack propagation, transforming brittle thermoplastics into tough engineering grades.
Thermal Stability
Thermal degradation of the elastomer occurs under high melt temperatures. Gelation reduces impact strength. The molded part becomes brittle.
