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