The rheological behavior of elastomers of polydimethylsiloxane vinyl-terminated has been investigated in both rotational and oscillating modes. Partially crosslinked liquid rubbers have been prepared, varying the curing agent-to-elastomer weight ratio p. Viscoelastic fluids with unusual rheological properties have been obtained. For small p, zero-shear viscosity and storage dynamic modulus G′(ω) at low frequencies are obtained, lower than those of reference liquid elastomers. Outcomes are discussed according to the polymer tube model theory and an extension at nanoscale of the Einstein equation of viscosity proposed. The unentangled crosslinked nanodomain model has been proposed. At light networking, isolated crosslinked nanodomains would form and the longer chains will be preferentially bonded. This will determine a decrease in the entanglement density in the matrix. On the nanodomain surface the dangling chains will not be long enough to give stable entanglements, determining the formation of a free volume at the interface polymer matrix-nanoparticles.
Unusual Rheological Properties of Lightly Crosslinked Polydimethylsiloxane
Villani, Vincenzo
;LAVALLATA, VITO
2017-01-01
Abstract
The rheological behavior of elastomers of polydimethylsiloxane vinyl-terminated has been investigated in both rotational and oscillating modes. Partially crosslinked liquid rubbers have been prepared, varying the curing agent-to-elastomer weight ratio p. Viscoelastic fluids with unusual rheological properties have been obtained. For small p, zero-shear viscosity and storage dynamic modulus G′(ω) at low frequencies are obtained, lower than those of reference liquid elastomers. Outcomes are discussed according to the polymer tube model theory and an extension at nanoscale of the Einstein equation of viscosity proposed. The unentangled crosslinked nanodomain model has been proposed. At light networking, isolated crosslinked nanodomains would form and the longer chains will be preferentially bonded. This will determine a decrease in the entanglement density in the matrix. On the nanodomain surface the dangling chains will not be long enough to give stable entanglements, determining the formation of a free volume at the interface polymer matrix-nanoparticles.File | Dimensione | Formato | |
---|---|---|---|
macp.201700037_R1.pdf
solo utenti autorizzati
Descrizione: Unusual rheological properties of lightly crosslinked Polydimethylsiloxane
Tipologia:
Documento in Post-print
Licenza:
DRM non definito
Dimensione
1.48 MB
Formato
Adobe PDF
|
1.48 MB | Adobe PDF | Visualizza/Apri Richiedi una copia |
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.