The intermediate layer should have {HEAD ~ a flexural modulus} of {TAIL ~ 50,000 psi} or greater 
of
The intermediate layer should have { HEAD ~ a flexural modulus } of { TAIL ~ 50,000 psi } or greater
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH