Blend compatibility study by solid-state C-13 nuclear magnetic resonance

The application of proton spin-lattice relaxation time in the rotating frame and carbon-13 cross-polarization/magic-angle spinning to investigate the compatibility of a polymeric blend formed by high-density polyethylene (HDPE) and a synthetic petroleum resin of low molecular weight showed that this system presents a range of compatibility varying up to 40% (w/w) of the petroleum resin. The blends showed a shift of the NMR lines to short contact time-i.e., a rigid region. The 60/40 blend clearly displays the presence of domains of distinct mobility: one rigid (short contact time) and the other flexible (long contact time), indicating phase separation. Thus, besides the crystalline phase of HDPE, the blends show two amorphous phases: one rich in the polyolefin and the other rich in the low-molecular-weight component. (C) 2000 Elsevier Science Ltd. All rights reserved.