Terminologies such as tailored bimodal or controlled long-chain branching discuss the addition of difunctional diene monomers such as vinylnorbomene or hexadiene
comonomers that essentially couple the polymer chains to form an H-branched structure.
Especially the hexadiene
comohomer showed a different behavior and it was succeeded to incorporate as much as 7 mol% of this comonomer in the chain compared to only 2.4 mol% of the octadiene (OD) and methyloctadiene (MOD).
Non-conjugated diene monomers such as ethylidene norbornene (ENB), hexadiene
(HX) and dicyclopentadiene (DCPD) are added to ethylene propylene polymers to provide unsaturation sites for curing purposes.
The ethylenenorbornene type of unsaturation is more active in combining with the sulfur and accelerators than dicyclopentadiene (DCPD) or 1,4 hexadiene
. The ultra fast cure rate will achieve a rapid development of physical properties, such as compression set, by establishing a higher crosslink density in a shorter time frame.
Some of these polymers contain ENB as a cure site, while others contain 1,4, hexadiene
(HD) as a cure site.
Incorporation of a diene (such as ethylidene norbomene or hexadiene
) pendant to the backbone of EPM produces EPDM.
* components which have a high sensitivity (such as ethylene norbornene [ENB], dicyclopentadiene [DCPD] and hexadiene
[HD]) and compounds which contain displaceable unsaturated bonds, such as 1,2-vinyl compounds and methacrylates;