Preparation and characterization of core-shell magnetite nanoparticles-polycaprolactone, core-shell natural rubber- polycaprolactone for toughness enhancement of poly(lactic acid)
The core-shell magnetite nanoparticles or natural rubber coated with polycaprolactone
(PCL) (mag-ad-PCL) or (NR-ad-PCL) was synthesized by admicellar polymerization
and used as a toughening agents for poly(lactic acid) (PLA). Moreover, PLA composites
(mag-ad-PCL) at 0.5, 1.0, 1.5, and 2.0 parts per hundred resin (phr) improved the mechanical
properties of PLA/NR-ad-PCL blend at ratio 95:5. The morphology of the PLA/NR-ad-
PCL blend and the PLA composites showed good interfacial adhesion which possessed the
superior toughened PLA. The glass transition temperature (Tg) slightly decreased and the
crystallinity of the PLA composites increased with increasing mag-ad-PCL. The strength of
the PLA composite at 1.5 phr increased by up to 61%. Ultimately, the PLA composite at
1.5 phr showed the highest impact strength (three times that of pure PLA) at 1.5 phr and the
elongation at break of the blend with PLA composite at 0.5 phr was ten times higher than that
of pure PLA. The toughening mechanism showed synergistic behavior which was the
interaction between rubber particle cavitation and the particle reinforcing/bridging mechanism.