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

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. (C) 2000 Elsevier Science Ltd. All rights reserved.