Temperature variations of NMR second moments for drawn tapes based on polypropylene and polyethylene

Isotropic and drawn tapes prepared from isotactic polypropylene (PP), low density polyethylene (LDPE) and their blend PP/LDPE (70/30) have been studied by broad‐line nuclear magnetic resonance (NMR) in the temperature range from 120 up to 320 K. The glass‐transition temperatures, T_g, for studied samples have been determined from the temperature dependencies of the NMR second moments. It was found that the NMR spectra and their second moments are additive for isotropic blend in the whole temperature range, while a significant differences from addition rule appear for drawn PP/LDPE blend, when weighted average second moment is calculated by means of second moments of equally drawn homopolymers. It was found out that the LDPE component in the blend is drawn to a greater extent than PP component.