This study investigates low‐density green polyethylene (LDPE) nanocomposites reinforced with bamboo‐derived cellulose nanocrystals (CNCs) and compatibilized with polyethylene‐graft‐maleic anhydride (PE‐g‐MA). Four materials were prepared by melt extrusion and injection molding (neat LDPE; LDPE with 1.0 and 1.5 wt% CNCs; and LDPE with 1.0 wt% CNC + 1.0 wt% PE‐g‐MA) and evaluated by thermal, mechanical, and structural analyses. Fourier‐transform infrared spectroscopy (FTIR) indicated interactions between maleic‐ anhydride groups and CNC hydroxyls, supporting improved interfacial compatibility. X‐ray diffraction (XRD) showed increased crystallinity in CNC‐containing samples, consistent with a nucleating effect. Thermogravimetric analysis/derivative thermogravimetry revealed single‐step LDPE decomposition with an upward shift of the degradation‐rate peak upon CNC addition; residues remained below at these low loadings. Under uniaxial tension, stiffness increased significantly at 1.5 wt% CNC and in the compatibilized composite, while tensile strength improved only with PE‐g‐MA; elongation decreased with CNCs irrespective of compatibilizer, remaining highest for neat LDPE. After accelerated aging (UV + humidity), modulus and strength exhibited modest declines across all materials, comparatively larger in the compatibilized system, suggesting time‐dependent changes at the CNC‐matrix interface. Overall, bamboo‐CNC/PE‐g‐MA provides a sustainable route to tailor thermal performance and load‐bearing response of LDPE for applications that prioritize stiffness and thermal resistance over ductility.

Expanded polystyrene (EPS) waste is a major environmental concern, yet practical routes to upgrade it into higher value-added materials remain limited. Here, post-consumer EPS was dissolved in ethyl acetate and solvent-cast into films containing cellulose nanocrystals (CNCs) and a sunflower oil. Three formulations were produced: F-EPS (100% EPS), F-EPS + CEL (80% EPS/20% CNC), and F-EPS + CEL + OIL (80% EPS/15% CNC/5% oil). CNC markedly enhanced optical shielding, reducing transmittance at 400 nm from ≈58% (F-EPS) to ≈18% (CNC containing films). All films remained hydrophobic, showed negligible water uptake, and exhibited low mass loss after 30 days of accelerated weathering ($\Delta M=1$–$3\%$). Tensile testing showed that F-EPS had the highest UTS and elongation at break (10.0 ± 0.6 MPa and 10.5 ± 0.4%), whereas adding cellulose increased the elastic modulus (249.5 ± 29.0 MPa to 358.4 ± 64.8 MPa) but reduced UTS and elongation (8.2 ± 0.2 MPa and 5.4 ± 2.5%). Oil addition led to a further reduction in UTS and elongation (6.2 ± 0.4 MPa and 3.6 ± 0.0%), while the modulus returned to a value statistically similar to neat F-EPS. FTIR and XRD confirmed preservation of the EPS chemical fingerprint and a predominantly amorphous structure ($2\theta \approx 20$–30°). Overall, EPS + CNC + OIL films combine hydrophobicity, UV-screening, and elastic modulus similar to neat F-EPS, supporting their use as moisture-resistant, UV screening protective topcoats for non-food-contact paperboard packaging.

Poly(vinyl alcohol) (PVA)-based films containing glycerol and quercetin were prepared by casting as potential active-packaging materials. The effects of the glycerol/quercetin ratio on structural, thermal, mechanical, barrier, and antioxidant properties were investigated. Neat PVA and ternary formulations with PVA/glycerol/quercetin ratios of 70/20/10 (PVA+Gly+Q10) and 70/10/20 (PVA+Gly+Q20) by mass were characterized by FTIR, XRD, SEM, contact angle, TGA/DTG, tensile testing, water vapor permeability (WVP), total phenolic content, and DPPH assays. FTIR indicated changes in hydrogen bonding without new covalent functionalities, while apparent whole-film crystallinity indices were 16.2%, 11.1%, and 10.6%, respectively. Tensile tests included additional glycerol-rich and quercetin-rich endpoint controls to characterize the mechanical range of the formulation series. Neat PVA exhibited the highest maximum stress ($15.67\pm 1.49$ MPa). PVA+Gly+Q20 showed a strain at break of $256.87\pm 115.68$% and an apparent tensile modulus of $26.61\pm 3.40$ MPa. The glycerol-rich endpoint exhibited high extensibility, whereas the quercetin-rich endpoint showed a markedly higher apparent tensile modulus ($404.69\pm 45.72$ MPa). DPPH activity increased from 11.18% for PVA to 35.38% and 44.31% for PVA+Gly+Q10 and PVA+Gly+Q20, respectively. PVA+Gly+Q20 also exhibited approximately 68% lower mean WVP than PVA+Gly+Q10, with no significant formulation effect. These results support further development of PVA+Gly+Q20 for active packaging.