Dr. Nisar, Muhammad

In recent years, biodegradable plastics have gained significant attention as a strategy to reduce environmental contamination. However, achieving uniform dispersion of magnetic nanoparticles (MNPs) in polymers remains challenging due to magnetic aggregation. Core-shell encapsulation has emerged as an effective method to address this issue. In this study, nickel (Ni) nanoparticles (NPs) were supported on thermally reduced graphene oxide (TrGO), reduced at two distinct temperatures (600 and 1000°C), and used as nano-fillers to fabricate PLA nanocomposites. The mechanical, thermal, and magnetic properties of these composites were systematically investigated. X-ray diffraction (XRD) analysis displayed characteristic peaks for both graphene and Ni, with an estimated Ni NP size of 3.59 nm. Raman spectroscopy confirmed the D and G bands of graphene, along with distinct peaks of Ni. Surface area and elemental analyses indicated an increase in surface area and carbon content with thermal reduction, followed by a predictable decrease after supporting Ni NPs. Atomic absorption spectroscopy revealed that 8–12 wt.% of MNPs were successfully loaded onto the TrGO surface. Fourier transform infrared spectroscopy (FT-IR) demonstrated that the polymer's chemical structure remained unchanged after nanoparticle incorporation. Uniform dispersion of the filler was observed through fracture interface scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) showed a slight improvement in the initial degradation temperature of the PLA nanocomposites upon NP addition, although the final thermal stability was lower compared to neat PLA. Differential scanning calorimetry (DSC) showed a small increase in crystallinity, while the melting temperature remained unchanged. The addition of the filler led to a slight improvement in the elastic modulus. The hydrophilic nature of the nanocomposites was confirmed by water contact angle measurements. Notably, the incorporation of TrGO-Ni nanoparticles converted the original diamagnetic PLA matrix into a ferromagnetic material.

The use of biodegradable polymers to mitigate the environmental pollution is one of the hot topics of research in the recent years. The current work presents the graphene oxide (GO) nanoparticles functionalized with two types of alkylamines (decylamine (DA) and octadecylamine (ODA)) synthesized at two different temperatures; 25 ◦C (GODA1 and GOODA1) and 80 ◦C (GODA2 and GOODA2), which were used as fillers to prepare PLA nanocomposites and their barrier, mechanical, and thermal properties were studied. The elemental analysis showed 2 wt% to 4 wt% of nitrogen content for functionalized GO, confirming the presence of alkyl chains in its structure. The reactions carried out at 80 ◦C (GODA2 and GOODA2) are the ones that showed the highest mass yields, registering a 7% and 50% increase in the total mass, respectively. These results were supported by X-ray diffraction (XRD), FT-IR spectroscopy and thermogravimetric Analysis (TGA) analyses. The optical microscopy images of the nanocomposites showed that the modified GO has a higher affinity than the GO with the PLA matrix, observing good dispersion at low loads of modified GO (0.2 wt%), with an increasing tendency to form agglomerates for higher loads. Furthermore, the elastic modulus of all nanocomposites showed a decreasing trend, mainly attributed to the formation of agglomerates and the decrease in the crystallinity of the composites. The oxygen permeability progressively decreases with increasing nanoparticle load, the nanocomposites pre- pared with GODA2 and GOODA2 presented the best results, registering decreases of 28.6% and 30.4% for 2 wt% loads, respectively. On the other hand, the permeability to water vapor decreased by 36.0% and 50.2%, for loads of 0.2 wt% of GODA2 and GOODA2, respectively. However, for higher amount of filler no significant im- provements was detected. The results shows that the addition of modified GO to PLA improves its barrier properties, and that its composites could be used in food packaging.