Thermoplastic polyurethane (TPU)-based
biomaterials are widely
investigated in fabricating biomedical implants and devices. The present
study describes a dynamic vulcanization-inspired reactive melt-blending
methodology to modify TPU with polydimethylsiloxane (PDMS) and ensure
the selective in situ crosslinking of the PDMS phase.
The influence of the peroxide crosslinker during melt-processing was
assessed, and, thereupon, a complete set of dynamically vulcanized
blends was prepared with varying PDMS contents (10–40 wt %).
The obtained thermoplastic vulcanizates (TPVs) were characterized
for their crosslink density, mechanical properties, morphology, and
thermal stability; and benchmarked against the uncrosslinked, pristine
blends. The fractographic examination of the blend surfaces demonstrated
a remarkable improvement in interfacial adhesion and a more refined
microstructure for the TPVs, while a gross phase-separation was evident
in the uncrosslinked blends. The experimentally determined tensile/compression
response for the dynamically vulcanized system was in good agreement
with the theoretical predictions, based on the Halpin–Tsai,
Coran, and Takayanagi models. The pristine blends, devoid of crosslinking,
largely conformed to the lower-bound series model, implying an immiscible
and uncompatibilized behavior. The analysis of stress-concentration
parameters was also performed to gain further insights into the discontinuities
in the stress transfer in the dual-phase blend system. Taken together,
the obtained results affirmed the superior properties of TPVs and
established the efficacy of dynamic vulcanization for the in situ compatibilization of the TPU/PDMS system, in good
corroboration with the predictive models.