Measurement of fiber density by helium pycnometry

Fiber and void volume fractions of polymeric composite materials are often measured as indicators of part quality. However, accurate fiber and void vo lume fraction measurements require that the fiber density be known to a hig h degree of accuracy. Helium pycnometry offers the potential for accurate f iber density measurements. In this study, helium pycnometry was used to mea sure the density of E-glass, S2-glass, and carbon fibers. Results were comp ared with those of other fiber density measurement techniques. The density of E-glass was determined to be 2.6173 g/cc. S2-glass was found to have a d ensity of 2.4858 g/cc. Measured carbon fiber densities were 1.7635 g/cc for Toray T300, and 1.7758 g/cc for Hercules IM7.