Densification of a polymer glass under high-pressure shear flow

Owen Brazil, H. Özgür Özer, Benjamin Watts, John B. Pethica, Graham L.W. Cross*

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Özet

The properties of glasses can change significantly as they evolve toward equilibrium. Mechanical deformation appears to influence this physical aging process in conflicting ways, with experiments and simulations showing both effects associated with rejuvenation away from and overaging toward the equilibrium state. Here we report a significant densification effect in a polymer undergoing shear flow under high pressure. We used the high-aspect ratio geometry of the layer compression test to measure the uniform and homogeneous accumulation of plastic strain during isothermal confined compression of a deeply quenched film of polystyrene glass. Combined scanning transmission x-ray microscopy (STXM) and atomic force microscopy confirmed defect-free deformation leaving up to 1.2% residual densification under conditions of confined uniaxial strain. At higher peak strain, plastic shear flow extruded glass from below the compressing punch under conditions of a high background pressure. A further density increase of 2% was observed by STXM for a highly thinned residual thickness of polymer that nevertheless showed no signs of crystallization or internal strain localization. While the confined uniaxial densification can be accounted for by a simple elastic-plastic constitutive model, the high-pressure extrusion densification cannot.

Orijinal dilİngilizce
Makale numarasıL060103
DergiPhysical Review B
Hacim106
Basın numarası6
DOI'lar
Yayın durumuYayınlandı - 1 Ağu 2022

Bibliyografik not

Publisher Copyright:
© 2022 American Physical Society.

Finansman

O.B., J.B.P., and G.L.W.C. acknowledge funding from the Science Foundation Ireland–funded AMBER research center (SFI/12/RC/2278). We acknowledge the Paul Scherrer Institut, Villigen, Switzerland for provision of synchrotron radiation beamtime at the PolLux beamline of the SLS. The PolLux end station was financed by the German Ministerium für Bildung und Forschung (BMBF) through Contracts No. 05K16WED and No. 05K19WE2.

FinansörlerFinansör numarası
German Ministerium für Bildung und Forschung
Science Foundation IrelandSFI/12/RC/2278
Bundesministerium für Bildung und Forschung05K16WED, 05K19WE2

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