The sheet 24 may either be {HEAD ~ a plain thermoplastic material} or {TAIL ~ a thermoplastic material} reinforced with fibers 
The sheet 24 may either be { HEAD ~ a plain thermoplastic material } or { TAIL ~ a thermoplastic material } reinforced with fibers
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH