An expanded cellular ethylenic polymer product is provided from an irradiated,
noncross-linked linear ethylenic polymer. Linear ethylenic polymers can be irradiated
at ambient conditions sufficient to introduce branching in the polymer in the absence
of detectable cross-linking as indicated by the absence of gels. The irradiated
linear ethylenic polymer is compatible with highly branched low density polyethylene
and, when mixed therewith, produces a resin having a single broad based melting
temperature range as determined by direct scanning calorimetry, which indicates
that the polymers in the mixture have similar crystallization behavior suitable
for producing low density foams by extrusion foaming. The linear polymers can be
obtained from recycled shrink wrap film. Low densities of from 0.7 to less than
4 pcf can be achieved. The foams typically have improved tear resistance as compared
to previous products prepared from low density polyethylene, at comparable low densities.
