Rheological properties of short melamine fibre filled EPDM rubber

The effects of concentration of short melamine fibres and of a dry bonding system consisting of resorcinol, silica, and hexamethylene tetramine on the rheological properties of EPDM rubber Compounds have been investigated usi ng a capillary rheometer. All the compounds behaved as pseudoplastic materi als and followed the power law model. It was found that the apparent viscos ity of the compounds shows a maximum at 40 pphr fibre loading. It was also observed that all three components of the dry bonding system must be presen t together to decrease the die swell of the extrudates. Morphological analy sis of the extrudates using scanning electron microscopy revealed that melt fracture, which is observed at higher shear rates for the compositions con taining no fibres, is absent in the compositions containing fibres. An alig nment of the fibres in the shear field was also observed in the micrographs of cross-sections through the extrudates.