The performance of gamma irradiation and pineapple-derived nanocellulose for advanced PLA/PBAT materials

Abstract

This study presents an innovative approach to addressing the challenges of phase immiscibility and poor interfacial adhesion in polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) blends by integrating gamma radiation-induced modifications and with nanocellulose reinforcement, offering a novel option to high-performance, eco-friendly materials that balance sustainability with functionality. Cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) were extracted from pineapple leaf fibers (PALF), which contain 50.5% cellulose, demonstrating their potential as a valuable source for nanocellulose production. Optimized hydrolysis conditions (55% H2SO4, 45ºC, 20-50 mg/mL) yielded CNCs with high crystallinity and minimal thermal degradation, achieving yields of 55-61%. Conversely, CNFs processed via ball milling for 196-360 hours exhibited disrupted crystallinity and aggregated structures, reclassified as cellulose nanoparticles (CNPs). Gamma irradiation using Co-60 was applied to induce chain scission in PLA, enhancing its interaction with PBAT through free radical formation. High doses (80-150 kGy) caused excessive degradation, reducing mechanical properties despite improved interfacial adhesion. In contrast, low doses (3-5 kGy) significantly improved mechanical properties (7.7% increase in tensile strength for 3 kGy, 12.9% increase in elongation at break for 5 kGy) and thermal stability (5.3ºC increase) while preserving rheological and viscoelastic characteristics. Incorporating 1-3% CNP into high-dose irradiated blends did not enhance mechanical or rheological properties due to material degradation and low fibrillation but improved thermal stability and crystallinity in non-irradiated blends. Environmental implications were significant, as gamma irradiation and nanocellulose incorporation accelerated biodegradability, making these blends suitable for sustainable packaging applications.