Preparation and Thermal Characterization of PTFE/PES Nanocomposites

PTFE/PES composites were prepared by precipitation of Radel A1 into a PTFE latex containing nanoparticles with average diameters of 48 nm and spherical shape. Several samples were prepared by varying the relative ratio between the Radel A1 and PTFE content. The combination of SEM and AFM analysis indicates that the precipitation of Radel A in the presence of PTFE leads mainly, if not exclusively, to a bimodal mixture of the two homoparticles. The fractionated crystallization behaviour of these samples is revealing of the PTFE dispersion degree within the Radel A1 matrix. When the PTFE amount is lower than 2%, a perfect PTFE nanoparticle dispersion is obtained. When the amount of PTFE is comprised between 5 and 30%, larger PTFE clusters are obtained that, after melting, coalesce and crystallize at higher temperatures depending on the crystallization propensity of their individual heterogeneous nuclei. Finally, in case of samples 40%, only one crystallization exotherm is observed at 310 8C indicating the formation of very large clusters that after melting coalesce into wide domains.