Analyzing Impact Strength Improvement in Polymer Laminates: A Comparative Study of Machine Direction Oriented (MDO)-PE/LLDPE and Polyamide (PA)/LLDPE Structures

Abstract

The mechanical strength of 2 film structures, machine-direction-oriented polyethylene (MDO-PE) laminated with linear low-density polyethylene (LLDPE) and polyamide (PA) laminated with LLDPE was evaluated. PA/LLDPE films demonstrated superior impact strength (0.834 J/mm²) compared to MDO-PE/LLDPE films (0.445 J/mm²). Tensile strength for modified LLDPE (C₆) was 40 N/mm², higher than standard LLDPE (C₈) at 33 N/mm². The elongation at break for LLDPE reference C₈ was 689 %, compared to 682 % for LLDPE sample C₆. Film stiffness was measured at 162 MPa for the LLDPE reference C₈ and 122 MPa for the LLDPE sample C₆. PA films exhibited increased mechanical strength due to their intrinsic polyamide structure, while MDO-PE films benefited from molecular orientation during production. The modified LLDPE or C₆ displayed improved impact resistance and tensile strength with reduced stiffness. MDO-PE/LLDPE films are promising for sustainable and robust food packaging. HIGHLIGHTS Comparative Mechanical Strength of Films: Polyamide (PA) films, owing to their chemical structure rich in amide groups, exhibit superior mechanical strength compared to machine direction-oriented polyethylene (MDO-PE) films. Peeling Strength Dynamics: PA/LLDPE laminates display greater initial peeling strength; however, MDO-PE/LLDPE laminates show a gradual increase in peeling strength, indicating potential for improved long-term adhesion. Impact of LLDPE Density on Mechanical Properties: A comparison between LLDPE C₈ and LLDPE C₆ highlights the influence of polymer density on mechanical characteristics, with LLDPE C₆ demonstrating enhanced impact and tensile strengths at the expense of modulus and elongation. Strength Variability Among Laminates: The mechanical properties of laminated films are significantly influenced by the nature of their constituent layers, revealing the complexity of integrating polymers with differing characteristics. Potential of MDO-PE/LLDPE Laminates: Despite the superior properties of PA/LLDPE laminates, MDO-PE/LLDPE emerges as a viable alternative for sustainable and cost-effective packaging solutions, necessitating further validation to fully harness its advantages. GRAPHICAL ABSTRACT