At least a portion of the powder is mechanically attached to a surface of the cavity, where {HEAD ~ the mechanical attachment} of the powder allows {TAIL ~ a portion} of flame retardant particles of the powder to protrude beyond the surface and not be completely embedded therein 
allows
At least a portion of the powder is mechanically attached to a surface of the cavity , where { HEAD ~ the mechanical attachment } of the powder allows { TAIL ~ a portion } of flame retardant particles of the powder to protrude beyond the surface and not be completely embedded therein
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH