This is the python routine I used to calculate the linear viscoelasticity (storage and loss shear moduli) of worm-like microstructures define in the paper on linear viscoelasticity of IPNs. This routine may be used for any two-phase materials with the microstructure of your choice.You need two input.txt (phase1.txt and phase2.txt) files for the behavior constitutive...

The objective of the study was to characterize and model the linear viscoelasticity of interpenetrated polymer networks showing two clear distinct phase transitions. For this purpose we made in lab some acrylate IPNs by UV curing. In order to avoid fracture of the sample during the making process, the first single network is a lightly...

With industrial partner Arianegroup, we studied the mechanical behavior of three propellant-like materials. Two materials were made of an inert matrix with about 55% of sifted 250 microns ammonium perchlorate (AP) or RDX particles. The last material was the polymer matrix filled with about 20% of aluminium 3 microns particles and filled with AP fillers....

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...

The linear viscoelasticity of several carbon-black filled SBRs were characterized by DMA tests on a DMAQ800 dynamic uniaxial tension machine from TA. Figure 1. Storage modulus and damping factor of several carbon-black filled SBRs measured by uniaxial tension DMA tests. Materials are made of the same gum and filled with 0, 5, 30, 40, 50...