The application of proton spin-lattice relaxation time in the rotating fram
e and carbon-13 cross-polarization/magic-angle spinning to investigate the
compatibility of a polymeric blend formed by high-density polyethylene (HDP
E) 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 pe
troleum 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 t
he crystalline phase of HDPE, the blends show two amorphous phases: one ric
h in the polyolefin and the other rich in the low-molecular-weight componen
t. (C) 2000 Elsevier Science Ltd. All rights reserved.