Nano-indentation of polymer–glass interfaces Part I. Experimental and mechanical analysis

Abstract

The interface region in polymer/glass composite materials was investigated by means of the nano-indentation and the nano-scratch techniques. The nano-indentation test involved indentations as small as 30 nm in depth in order to detect the material properties in the transition region between the fibre and the matrix. A line of nano indents was produced along the 14 μm path starting from the matrix and ending on the fibre. The distinct properties of the transition zone were revealed by 2–3 indents. The nano-scratch test involves moving a sample while being in contact with a diamond tip. The coefficient of friction, defined as the ratio of the tangential force from the tip–sample contact to the normal force, also indicated a transition zone of different width. Analysis of the results allowed elimination of effects due to: (i) indenter width and its geometry; (ii) stress field and plastic zone interactions, to arrive at true interphase width as a material characteristic. These two techniques proved to be useful tools in the investigation of the size and the character of the interphase region in the fibrous polymer/glass composite materials.