CELLULOSE FREE-VOLUME CHARACTERIZATION USING POSITRON-ANNIHILATION LIFETIME SPECTROSCOPY

Positron annihilation lifetime (PAL) spectroscopy is a material micros tructure analysis technique that can provide information on the concen tration and dimensions of free volume holes or pores in the size range of tens of nanometres in amorphous and semicrystalline polymeric mate rials. In this study, PAL measurements have been performed on Avicel a nd Whatmann CF11 celluloses and their ball-milled derivatives, as well as on cellulose acetates. These results were correlated with fraction al accessibility/crystallinity data obtained using corresponding deute rated samples in combination with Fourier transform infrared spectrosc opy (FTIR). Moisture sorption was used to confirm the accessibility an d microstructure of these cellulose samples. Correlation of PAL and FT IR of deuterated celluloses and moisture sorption results demonstrated that PAL can be a useful technique for cellulose microstructure chara cterization.