Characterization of Randomly Branched Poly(vinylidene fluoride)

Abstract

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 (R G ) 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.

From Vinylidene Fluoride (VDF) to the Applications of VDF-Containing Polymers and Copolymers: Recent Developments and Future Trends

“…Recently, Arkema tailored various homopolymers of VDF to obtain unexpected morphologies of PVDF. Long chain branches (LCB) were synthesized using potassium persulfate and nbutyl-4,4-bis(tert-butylperoxy)valerate 72,73 . The number of branch points per 1000 monomer units was assessed by NMR to be in the 4.0-4.8 range while for "reference Kynar PVDF", this number ranged between 0.8 and 3.1.…”

Characterization of the Chain-Ends and Branching Structures in Polyvinylidene Fluoride with Multidimensional NMR

“…The viscoelastic properties of a polymer, which determine its performance during processing, are known to depend on factors such as chain branching. 16 Branching in PVDF or VDF-based fluoropolymers/fluoroelastomers can be short chain branches (SCB's) or long chain branches (LCB's). SCB's are usually produced from intramolecular hydrogen abstraction in a polymer chain; this is the so-called backbiting reaction.…”

Rheological properties and morphological evolutions of polypropylene/ethylene‐butene copolymer blends

“…In the low‐frequency region, the complex viscosity of the PEB is higher than that of the PP. Moreover, while the PP reaches its Newtonian plateau in the lowest frequency region, the PEB is still far from reaching it, which is characteristic of a branched polymer [44]. Incorporation of the PEB into the PP greatly decreases its complex viscosity in the entire frequency range.…”