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Contact mechanics for Polydimethylsiloxane: from liquid to solid

Abstract

Adhesion between a glass ball and a Polydimethylsiloxane (PDMS) sample being dependent on the PDMS cross-link density, when the material is transformed from the liquid state to the solid state is below investigated. The physical picture reflected a gradual transition from capillary forces driven contact mechanics to the classical Johnson-Kendall-Roberts (JKR) type contact mechanics. The PDMS was produced by mixing the base fluid and cross-linker in the ratio 10:1 and allowed to slowly cross-link at room temperature with simultaneous measurement of ball-PDMS interaction force. The PDMS sample was in the liquid state during the first ≈ 16 hours, and in this case the ball-PDMS interaction was purely adhesive, i.e., no repulsive interaction was observed. Later at the PDMS gel-point the cross-linked PDMS clusters percolate, converting the fluid into a soft (fluid-filled) poroelastic solid. In the transition period PDMS appears similar to pressure sensitive adhesives. There we observe so-called "stringing" and permanent deformation of the material impacted by the ball. At room temperature it takes more than 100 hours for the PDMS to fully cross-link that can be confirmed by the comparison with the earlier-studied reference PDMS produced at elevated temperatures.

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Publication details

The article was received on 10 Nov 2017, accepted on 29 Dec 2017 and first published on 02 Jan 2018


Article type: Paper
DOI: 10.1039/C7SM02216F
Citation: Soft Matter, 2018, Accepted Manuscript
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    Contact mechanics for Polydimethylsiloxane: from liquid to solid

    L. Dorogin and B. N. J. Persson, Soft Matter, 2018, Accepted Manuscript , DOI: 10.1039/C7SM02216F

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