Polyoxymehtylene (POM)/multiwalled carbon nanotubes (MWCNTs)/glass fiber (GF) and POM/carbon black (CB)/GF composites were prepared by melt mixing in a rotational rheometer.The effects of GF on the electrical conductivity

crystallization behavior and dynamic mechanical properties of the composite materials were investigated.The morphology of the composites was observed by field emission scanning electron microscopy (FESEM)

showing that GF does not significantly affect the dispersion state of MWCNTs and CB.Although GF is electrically inert

its presence can increase the effective concentration of the conductive filler by holding up some space

therefore the conductivity of the material increases.The electrical resistivity/effective concentration data points are all around the electrical resistivity/conductive filler concentration curve of POM/MWCNTs and POM/CB composites

proving that the concept of effective volume concentration can be used to explain the decrease in the electrical resistivity with the incorporation of GF.The crystalline behavior of POM in the composites was investigated by differential scanning calorimetry (DSC).The crystallization temperature

melting temperature and degree of crystallinity have no significant change by incorporation of GF

revealing that GF does not have obvious influence on the crystalline behavior of POM.The storage modulus

as measured by dynamic mechanical analysis (DMA)

increases significantly by the presence of GF

showing a strong reinforcing effect.Therefore

GF-filled POM/MWCNTs and GF-filled POM/CB are promising materials having both good electrical conductivity and good mechanical properties.