The morphology and mechanical properties of emulsion blended samples of poly(tetrafluoroethylene) (PTFE) and poly(tetrafluoroethylene-co-vinylidine fluoride-co-hexafluoropropylene) (FKM) were investigated. Film samples with varying levels of PTFE content and varying degrees of FKM covalent cross-linking were produced. It was observed at room temperature that below 50 wt% PTFE content, cross-linking the FKM can have a much larger influence on the tensile modulus than changing the PTFE content. Above 50 wt% PTFE, however, the modulus showed a near exponential increase with respect to increasing PTFE content. Without cross-linking, the toughness of the cast blends was shown to systematically decrease as the PTFE content was increased. However, when the FKM was cross-linked in film-form with 20-60 wt% PTFE, more stress was apparently transferred to the PTFE particulate leading to a higher elongation-to-break and a higher toughness. DMA analyses revealed a systematic increase of the storage moduli with increasing PTFE content. A tan delta peak at ca. -10 degreesC was observed which corresponds to the glass transition of the FKM and the magnitude of this peak was observed to decrease systematically with decreasing FKM content or with increasing levels of FKM cross-linking. For the levels of cross-linking tested, however, this peak reduction due to cross-linking was not observed to be as significant as increasing the PTFE content. For all PTFE content levels studied, the transmission electron microscopy (TEM) examination revealed a dispersed morphology for the PTFE particulate with the FKM forming a continuous matrix. The PTFE particulate were observed to be ca. 0.2 mum in size and only slightly aggregated. The phase images from the tapping-mode atomic force microscopy showed that this is a useful technique for imaging morphology that lies parallel to the plane of the film surface, and for developing correlations with the TEM results of the bulk structure. (C) 2001 Elsevier Science Ltd. All rights reserved.