Impact of high-dose gamma irradiation on PLA/PBAT blends reinforced with cellulose nanoparticles from pineapple leaves

Abstract

Polylactic acid (PLA), a widely used biopolymer, faces limitations in melt strength and miscibility with poly(butylene adipate-co-terephthalate) (PBAT), requiring compatibilization strategies. This study uniquely investigates the combined effects of high dose of gamma irradiation (80–150 kGy) and low-aspect-ratio cellulose nanoparticles (CNPs) on PLA/PBAT blends, aiming to enhance compatibility and mechanical performance. Gamma irradiation induced chain scission and radical formation, improving blend compatibility but reducing mechanical properties at high doses due to excessive chain scission. Size exclusion chromatography revealed significant molecular weight reduction from chain scission, with partial recovery at higher doses due to cross-linking or recombination. Scanning electron microscopy (SEM) showed poor CNP dispersion in nonirradiated blends, causing agglomeration and weak interfacial adhesion, while irradiated blends exhibited improved CNP distribution and blend compatibility. Mechanical testing revealed no improvement in tensile strength with CNP addition, as agglomeration and poor dispersion hindered reinforcement, while irradiation-induced brittleness further reduced mechanical performance. Glass transition temperature and thermal stability decreased, as confirmed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Rheological analysis showed that CNPs did not significantly enhance viscosity or modulus, likely due to their irregular shape and lack of network formation. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) highlighted interactions between CNPs and the polymer matrix, with irradiation altering the chemical environment. Contact angle measurements indicated enhanced hydrophilicity with CNP addition in irradiated blends, while biodegradation tests revealed accelerated degradation for irradiated and CNP-reinforced samples. This work innovates by evaluating gamma irradiation and CNPs as compatibilization strategies for PLA/PBAT blends, while identifying limitations for future optimization.