Chiang Mai Journal of Science

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.