Structure and morphology of filled rubber and thermoplastic elastomers

Element spectroscopic imaging (ESI) technique in transmission electron microscopy (TEM) has been used to investigate the morphology and filler distribution in thermoplastic polyurethane (PUR) elastomers and filled rubbers. Single filler particles could be identified and imaged by ESI-TEM. Elastic bright field images of samples containing zinc stearate as a vulcanization accelerator showed a change in the morphology after vulcanization. An influence of the mixing time on the tiller distribution was found in that silica agglomerates and inhomogenities in the distribution of zinc oxide and titanium dioxide appeared at longer mixing times. The microphase separated morphology of segmented PUR elastomers could be visualized by imaging the net nitrogen distribution. The ESI micrographs of polyether urethanes with monodisperse or polydisperse hard segment distribution indicated a dramatic change in the hard domain morphology from relatively uniform cylinder domains (monodisperse hard segment) to more irregular and lamellar structures in polydisperse systems.