Submicrometric characterization of the heterogeneous photooxidation of polypropylene by microthermal analysis

Photoageing of polymeric materials is known to induce physical and chemical modifications. Until recently the analysis of such modifications was realized in the bulk. The objective of this study is to quantify at a submicrometric level the physical heterogeneity induced by the photooxidation of polypropylene. In a first step, the impact of the photooxidation on the physical and chemical properties are quantified by bulk analysis (DSC and FTIR experiments) of a "homogeneous" photoaged material. In a second step, depth profile experiments are performed by microthermal analysis (mu-TA) and FTIR microscopy (mu-IR). Our main finding is to show that the physical properties of the material can be defined with a sub-micrometric resolution by mu-TA experiments, resolution which cannot be achieved with the usual spectrophotometric measurements. (C) 2002 Elsevier Science Ltd. All rights reserved.