TY - JOUR

T1 - Planar elongation of soft polymeric networks

A1 - Jensen,Mette Krog

A1 - Hassager,Ole

A1 - Rasmussen,Henrik K.

A1 - Skov,Anne Ladegaard

A1 - Bach,Anders

A1 - Koldbech,Henning Vitus

AU - Jensen,Mette Krog

AU - Hassager,Ole

AU - Rasmussen,Henrik K.

AU - Skov,Anne Ladegaard

AU - Bach,Anders

AU - Koldbech,Henning Vitus

PB - Springer

PY - 2010

Y1 - 2010

N2 - A new test fixture for the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks with application towards pressure-sensitive adhesives (PSAs). The concept of this new geometry is to elongate a tube-like sample by keeping the perimeter constant. To validate this new technique, soft polymeric networks of poly(propylene oxide) (PPO) were investigated during deformation. Particle tracking and video recording were used to detect to what extent the imposed strain rate and the sample perimeter remained constant. It was observed that, by using an appropriate choice of initial sample height, perimeter, and thickness, the planar stretch ratio will follow lambda(t) = h(t)/h(0) = exp((epsilon)overdot t), with h(t) being the height at time t and (epsilon)overdot the imposed constant strain rate. The perimeter would decrease by a few percent only, which is found to be negligible. The ideal planar extension in this new fixture was confirmed by finite element simulations. Analysis of the stress difference, sigma(zz) - sigma(xx), showed a network response similar to that of the classical neo-Hookean model. As the Deborah number was increased, the stress difference deviated more from the classical prediction due to the dynamic structures in the material. A modified Lodge model using characteristic parameters from linear viscoelastic measurements gave very good stress predictions at all Deborah numbers used in the quasi-linear regime.

AB - A new test fixture for the filament stretch rheometer (FSR) has been developed to measure planar elongation of soft polymeric networks with application towards pressure-sensitive adhesives (PSAs). The concept of this new geometry is to elongate a tube-like sample by keeping the perimeter constant. To validate this new technique, soft polymeric networks of poly(propylene oxide) (PPO) were investigated during deformation. Particle tracking and video recording were used to detect to what extent the imposed strain rate and the sample perimeter remained constant. It was observed that, by using an appropriate choice of initial sample height, perimeter, and thickness, the planar stretch ratio will follow lambda(t) = h(t)/h(0) = exp((epsilon)overdot t), with h(t) being the height at time t and (epsilon)overdot the imposed constant strain rate. The perimeter would decrease by a few percent only, which is found to be negligible. The ideal planar extension in this new fixture was confirmed by finite element simulations. Analysis of the stress difference, sigma(zz) - sigma(xx), showed a network response similar to that of the classical neo-Hookean model. As the Deborah number was increased, the stress difference deviated more from the classical prediction due to the dynamic structures in the material. A modified Lodge model using characteristic parameters from linear viscoelastic measurements gave very good stress predictions at all Deborah numbers used in the quasi-linear regime.

KW - Planar elongation

KW - Non-linear rheology

KW - Filament stretching

U2 - 10.1007/s00397-009-0383-7

DO - 10.1007/s00397-009-0383-7

JO - Rheologica Acta

JF - Rheologica Acta

SN - 0035-4511

IS - 1

VL - 49

SP - 1

EP - 13

ER -