For example, Takahashi et al. reported decreased strain
hardening properties in a composite system of fillers and a
base low density polyethylene.12) They described as follow.
In case of plastic/filler composite system, during the uniaxial
elongation process, stress is not applied uniformly to the
base polymer around the glass fillers due to a heterogeneous
deformation in this polymer composite. The total stress for
the composite was low compared with that of pure polymer
system. Thus, the strain hardening property decreased