Evaluation of Polyethylene/Organoclay Nanocomposites by Low-field Nuclear Relaxation

Two polyethylene (PE) samples (named BF and ES) were blended with 5% organoclay by melt processing at different shear rates. X-ray diffraction (XRD) showed that the organoclay was incorporated into the PE matrices. From the results it was determined that the level of intercalation was very similar for both systems. The knowledge of molecular dynamics of PE nanocomposites is very important since it depends on the clay dispersion. Thus, the objective of this work was to employ a new technique to understand changes in the molecular mobility for these systems. The samples were characterized by proton nuclear spin-lattice relaxation time (T1H), which is measured in a low-field NMR spectrometer. The influence of the samples' preparation was evaluated through the relaxation data. For polyethylene resins, two values of relaxation parameter were found and they were attributed to mobile region (low value) and rigid region (high value). These values change after nanocomposite formation, confirming the changes in the resin matrix after organoclay was incorporated.