Effect of dicumyl peroxide content on morphological, viscoelastic and physical properties of dynamically crosslinked poly(vinylidene fluoride)/ethylene vinyl acetate copolymer blends

Blends of poly (vinylidene fluoride) (PVDF) and ethylene-vinyl acetate copolymer (EVA) were prepared through dynamic crosslinking using dicumyl peroxide (DCP). Initially PVDF/EVA blends were prepared using an internal mixer and DCP was added in varying contents (e.g., 0, 1, 2, and 4 phr). The effect of DCP content on melt processing, morphological, thermal, mechanical and rheological properties were investigated. The PVDF/EVA (50/50 wt%) without DCP had a co-continuous phase morphology. The different DCP contents in the blends resulted in a changed arrangement of the elastomeric phase in the thermoplastic matrix. The action of shear forces during the processing of the material led to a partial fragmentation of the crosslinked EVA phase. The addition of DCP increased the crystallinity degree as well as the crystallization peak temperature of PVDF when compared to the blend without DCP and the pure PVDF. The Thermogravimetric curves were very similar, which means that the addition of DCP did not significantly alter the thermal degradation events in the PVDF/EVA blend. There was an improvement in viscosity due to increase in DCP content, and hence less processability for the system. Creep behavior showed that the higher the DCP content in the blends, the lower the elastic deformation which the material undergoes. The material had a rise in mechanical properties achieved with dynamic crosslinking of EVA phase.