The co catalyst is initially contacted with {HEAD ~ either} of the transition metal catalyst or {TAIL ~ the electron donor} for a first contact time of 5 120 seconds 
of
The co catalyst is initially contacted with { HEAD ~ either } of the transition metal catalyst or { TAIL ~ the electron donor } for a first contact time of 5 120 seconds
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH