Ecofriendly composites based on poly (lactic acid) with nano-zirconium phosphate and nano-zinc oxide/zirconium phosphate: physicochemical and aging characteristics

Abstract

The search for sustainable polymers to replace those of fossil origin has been constant. Poli (lactic acid) (PLA) is one of the alternatives since it is a biodegradable and ecofriendly polymer. This work intended to aggregate zinc oxide (ZnO) and zirconium phosphate (ZrP) as a tentative to improve PLA crystallization and ultraviolet light stability. To easy the incorporation of ZnO in the ZrP the last one was pre-expanded with Jeffamine and following melting extruded PLA composites were prepared. X-ray fluorescence spectroscopy (EDX) showed that incorporation of ZnO (around 50%) in the host filler was successful. Carbonyl absorbance ratio revealed some PLA degraded during the processing. This ratio also increased by exposure to ultraviolet lamps, but ZnO showed best stabilization in the PLA/E-A/ZrP/ZnO. X-rays diffraction revealed that fillers pre-expanded with Jeffamine promoted better dispersion but some reduction on the PLA thermal stability was noticed. Fillers promoted a slight increment of the PLA glass transition temperature. The precursor PLA presented a unique melting peak and low degree of crystallinity (around 4%). Either by compression or by extrusion, PLA lonely and in the composites presented two melting peaks identified as α’ and α crystalline arrangements and an increase of crystallinity degree was achieved. The material addresses potential application as sustainable alternative for packaging industry.