Characterization of Randomly Branched Poly(vinylidene fluoride)

Poly(vinylidene fluoride) (PVDF) experimental samples containing sparsely distributed chain branching were compared to commercial reference samples. The results showed a lower onset of shear thinning for the branched samples over the reference counterparts. The storage modulus of the branched samples at low frequency shows a significant increase for the low-molecular weight sample while the higher-molecular weight sample showed a moderate increase suggesting a strong contribution of chain branching. The branched PVDF samples exhibited a lower radius of gyration (RG) and intrinsic viscosity than the commercial samples over the entire molecular weight range. NMR revealed the presence of tertiary carbons, suggesting that the branches are covalently bonded and not of a physical nature. Extensional viscosity data showed that the branched samples display a significant degree of strain hardening while the reference samples exhibit a small degree of strain hardening.