Size effect on mechanical properties of micron-sized PS–DVB polymer particles

• Published in: Polymer (Guilford) Vol. 49; no. 18; pp. 3993 - 3999
• Main Authors: He, J.Y., Zhang, Z.L., Midttun, M., Fonnum, G., Modahl, G.I., Kristiansen, H., Redford, K.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 26.08.2008; Elsevier
• Subjects: Applied sciences; Exact sciences and technology; Flat punch indentation; Mechanical properties; Organic polymers; Physicochemistry of polymers; Properties and characterization; PS–DVB particles; Size effect; Flat punch indentation; PS–DVB particles; Size effect; Compressive stress; Particle size; Stress strain relation; Nanoindentation; Crosslinked polymer; Mechanical properties; Microparticle; Styrene polymer; Spherical particle; PS-DVB particles;Flat punch indentation;Size effect; Experimental study
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2008.07.015

A nanoindentation-based flat punch method has been developed to determine the stress–strain behaviour of single micron-sized Ugelstad polystyrene-co-divinylbenzene (PS–DVB) particles in compression. Five groups of particles with identical chemical compositions but different diameters have been tested. The diameter of the PS–DVB particles varied from 2.6μm to 25.1μm. Constant relative deformation rate has been applied with two maximum strain levels of 5% and 10%. Results show that the particle compressive stress–strain behaviour is strongly size-dependent. The smaller the particle size is, the stiffer the particle behaves. Analyses indicate that the pre-load and adhesion during the flat punch test play a minor role on the size effect. The presence of a core–shell structure can possibly be a main contribution to the size effect. Finite element analyses have been carried out to demonstrate this surface shell effect. [Display omitted]