Development of eco-friendly bio-nanocomposites based on polycaprolactone, poly (lactic acid) and their blends with nanocellulose extracted from saccharum officinarum for advanced applications

Abstract

This thesis presents the development and characterization of biodegradable nanocomposites based on poly(lactic acid) (PLA), poly(ε-caprolactone) (PCL), and their blends reinforced with cellulose nanocrystals (CNCs) extracted from sugarcane bagasse. The research aimed to enhance the structural, thermal, morphological, and biodegradation performance of these polymers, thereby advancing sustainable alternatives to petroleum-based plastics. The work was organized in two parts: effects of CNCs on the individual matrices, i.e., neat PLA and PCL, and on the blended materials, i.e., PLA/PCL. In the first study, CNCs were incorporated into neat PLA and PCL to investigate their individual responses to reinforcement. The addition of CNCs promoted crystallinity and significantly increased the biodegradation rate of both polymers. 1 wt.% CNCs loading doesn’t show any impact on the biodegradation of PLA. 3 wt.% CNCs slightly increased the biodegradation rate of PLA with the weight loss of 8% at day 112, while 5 wt.% CNCs sped up the degradation of PLA and a wight loss 82.2% in the same period, although it reduced thermal stability and disrupted crystal ordering at higher loadings. In contrast, PCL showed minimal thermal changes but exhibited progressively faster biodegradation with increasing CNCs content. PCL/CNCs nanocomposites with 1, 3 and 5wt.% CNCs respectively exhibited a weight loss of 6.3, 12.1 and 36.4% at day 112, while neat PCL exhibited a weight loss of 5.4% at the same time. In the second study, PLA/PCL blends (70/30 and 30/70 wt.%) were reinforced with CNCs (1, 3, and 5 wt.%) and evaluated for their structure–property relationships. CNCs enhanced crystallinity, interfacial adhesion, and biodegradation. The incorporation of CNCs to PLA/PCL (30/70) increased the biodegradation rate with increasing CNCs content in the composite. The incorporation of CNCs to PLA/PCL (70/30); 1, 3 wt.% CNCs has no impact on the biodegradation, while the incorporation of 5 wt.% CNCs to PLA/PCL (70/30) sped up the biodegradation, achieving 100% mass loss within 112 days, compared to only 0.3% for neat PLA. Thermal stability improved slightly at a 1 wt.% CNCs loading but declined at higher concentrations. Tensile testing confirmed superior strength of neat PLA compared to PCL and PLA/PCL blends, although CNCs-reinforced nanocomposites could not be mechanically tested due to sample brittleness The findings show that CNCs derived from agricultural waste can improve the biodegradation and structural performance of PLA, PCL, and their blends. This thesis highlights the potential of sugarcane bagasse-derived CNCs as sustainable reinforcements for biopolymer systems, supporting the development of eco-friendly materials for packaging, biomedical, and other advanced applications.