Effect of PCL chain length on rheological and mechanical properties of PCL-PDMS-PCL triblock copolymer films

The polycaprolactone-polydimethylsiloxane-polycaprolactone (PCL-PDMS-PCL) triblock copolymer films of variable PCL chain are analyzed for rheological characteristics in this paper. The dynamics of viscoelastic behavior of photocrosslinked films above their crystal melting temperature (T-cm) is measured using oscillatory shear rheology experiments. The frequency sweep tests are analyzed at 0.1% strain as obtained from linear viscoelastic region. Shear thinning is observed in the study of complex viscosity. It has been noted that viscosity rises with increase in crosslink density and decrease in with PCL chain length. Time-dependent effect on the copolymer films has been analyzed by creep recovery behavior. The Burgers model is fitted in creep compliance data to analyze its viscoelastic and viscous region. An examination of structure recovery revealed that recovery increased as PCL chain length decreased. Tensile strength and percentage elongation are studied at ambient conditions with a universal testing machine, while storage modulus and tan delta are analyzed by a dynamic mechanical analyzer at varying temperatures.