The inner core can be comprised of cork, kapok, rubber or {HEAD ~ a blend} of thermoplastic polymers and {TAIL ~ copolymers} 
The inner core can be comprised of cork , kapok , rubber or { HEAD ~ a blend } of thermoplastic polymers and { TAIL ~ copolymers }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL