Thereafter, {HEAD ~ the reactor} is charged with the polymerization medium and ingredients in the usual manner and {TAIL ~ the polymerization reaction} commenced 
Thereafter , { HEAD ~ the reactor } is charged with the polymerization medium and ingredients in the usual manner and { TAIL ~ the polymerization reaction } commenced
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH