QUANTITATIVE MEASUREMENT OF VOID CONTENT IN GLASS-FILAMENT-WOUNDCOMPOSITES AND CORRELATION OF INTERLAMINAR SHEAR STRENGTH WITH VOID CONTENT E A R L
J.
KO",
A R T H U R
G .
S A N D S ,
A N D
R O B E R T
C .
C L A R K
Nacal Research Laboratory, Washington, D . C . 20390
Microvoid content ( < 1 volume O/o) of glass-filament-wound epoxy composites was determined by a precise statistical optical-counting technique. Thus, 8 to IO-mil specimens were cut parallel and normal to the fiber direction and coated with isopropylbiphenyl to reduce light scattering. The specimens were viewed under a microscope ( 4 5 0 X ) fitted with a micrometric disk engraved with a IO-mm. sq. net. A point-count technique, using 100 points in 10 separate areas, was used to calculate microvoid volume per cent. Regression correlation analyses established that a linear inverse relation existed between the interlaminar shear strength and the microvoid content of NO1 ring composites and indicated that reducing the microvoid content to
