Category: Past studies

The linear viscoelasticity and time-temperature superposition of solid polymers are often characterized using a torsion rheometer since it is a common equipment in polymer labs. Specimen are submitted to a dynamic torsion angle while the resulting torque is recorded. The torsion test gives access to the storage and loss shear moduli. When rectangular slender specimen...

We are currently interested in the catastrophic failure of carbon-black filled and unfilled elastomers submitted to monotonous loadings (not fatigue). First part of this work is to establish a clear criterion for mode I catastrophic fracture when it happens. For this purpose, single edge notch tension tests were run on three different materials, an unfilled styrene...

Why are we playing with rubber bouncing balls when we are kids ? Can metal or ‘plastic’ balls bounce as well ? And why do squash players warm up their balls before starting the game ? Let us have a little of recreation time bouncing balls and answer these questions. For that, some polymer balls are made in lab. The polymer is an...

In a previous post, I have presented some of our results obtained during stress-free shape memory recovery of amorphous polymer networks submitted to large deformation torsion tests. These tests introduce large deformation but moderate strain. In order to provide a rather complete set of data on the strain recovery and `stress recovery’ for amorphous polymers, including large strain, uniaxial...

  The shape memory property of amorphous polymer networks is the result of two intrinsic properties of these materials: 1) The viscoelasticity and 2) the time-temperature superposition property. This can be proven by characterizing the material linear viscoelasticity and time-temperature superposition with DMA (dynamic mechanical analysis) tests and by introducing these properties in a TRS (thermo-theologically...

  I started working on the shape memory property of polymers at CU Boulder thanks to Professor Ken Gall who introduced me to the topic. Focusing on amorphous polymer networks, with several co-workers we have been working on the characterization and the modeling of this property. This post is about the experimental characterization of the...