Gamma radiation induced property modification of poly(lactic acid)/hydroxyapatite bio-nanocomposites

Poly(lactic acid)/hydroxyapatite (PLA/HAP) nanocomposite films with various compositions, 2 - 70 parts HAP per 100 of the PLA polymer (pph), were made via the solution casting method. Transmission electron microscopy images of the PLA/HAP films exhibited spherical particles in the size range from nearly 10 nm to 100 nm dispersed within the polymeric matrix. Fourier transform infrared spectra of the nanocomposites revealed an interaction between PLA and HAP nanoparticles by carbonyl group peak shift. Incorporation of HAP nanoparticles in the PLA matrix stimulated crystal growth verified by differential scanning calorimetry. The films irradiated with gamma-rays at a dose of 30 kGy also showed an increase in crystallinity. The X-ray diffraction patterns of the irradiated PLA exhibited two new peaks at around 16 degrees and 19 degrees, assigned to the alpha crystalline phase of PLA; these were absent in the unirradiated nanocomposites. Significant ductile behavior was observed in both irradiated and unirradiated PLA nanocomposites containing 2 and 10 pph of HAP. However, the irradiated nanocomposites had higher tensile strength. (c) 2013 Society of Chemical Industry