Recently,
polyethylene (PE)-based single polymer composites (SPCs)
have been found to be potential candidates for high-voltage applications
(HVAs) due to their ability to form supramolecular structures and
their recyclabilities. However, a deeper understanding of the controls
and evolutions of such a structure is still needed. Herein, by introducing
elongational flow into the melt compounding, we could successfully
control the structure of polymeric materials and prepared PE-SPCs
with additive-level ultrahigh-molecular-weight polyethylene (UHMWPE)
for HVAs. The elongational flow-induced multiscale multilevel structure
was confirmed and analyzed through X-ray diffraction. Specifically,
under elongational flow, we fabricated PE-SPCs with the shish-kebab
structure and 2D variated crystal units. The melting behaviors of
each sample were studied, and the results indicated an elongational
flow-induced cocrystallization phenomenon of low-density polyethylene
and UHMWPE during melt processing. Benefiting from the as-formed structure,
we obtained PE-SPCs with enhanced mechanical properties and more HVA-adaptable
dielectric properties. Particularly, the yield strength, tensile strength,
and Young’s modulus of PE-SPC (sample R80) show 42, 23, and
29% enhancement than the virgin PE, respectively. The dielectric constant
and dielectric loss of our PE-SPC are determined to be around 2.94
and 2 × 10–4 at 1000 Hz, respectively. Moreover,
10-fold decreases in conductivites in both AC and DC of our PE-SPC
are achieved after melt compounding under elongational flow. In conclusion,
this work gives a comprehensive understanding of the PE-SPCs’
structure evolution under elongational flow, and the structure–property
relationship was also determined. It is believed that this work can
promote the development of SPCs for HVAs.
