MOLECULAR MOTIONS IN POLYETHERETHERKETONE (PEEK) - NMR ANALYSIS OF THE LOW-TEMPERATURE RELAXATION MECHANISM

The dynamic mechanical spectrum of PEEK at low temperature shows a rel axation band which is affected by the presence of water. A mechanism b ased on the interaction between water and oxygen atoms present in the polymer chain was previously suggested. In the present paper, direct e vidence of the role of the water at the molecular level is reported. T he analysis was carried out using two different experimental technique s, dynamic mechanical relaxation spectroscopy in monodirectional stret ching, and low-resolution solid-state nuclear magnetic resonance (NMR) spectroscopy. Both techniques give information on molecular mobility phenomena. The comparison between data obtained using the two techniqu es, and the analysis of samples with a controlled water content, suppo rts a model in which the motions of the water molecules play a relevan t role in the relaxation mechanism involving the polymer chains.