A Study for Mechanical Performance Optimization With <scp>GNP</scp> ‐Infused <scp>4C3PE</scp> Novel Composite Laminates for Liner‐Less Type‐V Hydrogen Storage Vessels

ABSTRACT This study investigates the mechanical performance of linerless Type‐V composite pressure vessels (CPVs) with a new laminate‐level scheme for high‐pressure hydrogen storage. A cross‐linked Hot‐pressed 4C3PE schema incorporates (4) carbon fiber (C) and (3) polyethylene films (PE) via compression molding, infused with (VARIM) with Bisphenol A diglycidyl ether and Diethylenetriamine as (DGEBA/DETA) epoxy system, and further modified by graphene nanoplatelets (GNPs). Thermomechanical analysis, by employing TGA, DMA, and DSC, evaluates the superiority of the 4C3PE cross‐linked scheme over the pristine epoxy system DGEBA/DETA and conventional 4 carbon 4C‐DGEBA/DETA stoichiometry. The optimal loading of GNPs at 2 wt.% enhances mechanical properties, increasing ultimate tensile strength (UTS) from 442 to 648 MPa as 46.6%, and with 35% increase in tensile modulus. Similarly, flexural strength increased from 120 to 234.5 MPa, with 95.8% and 60% increase in flexural modulus, demonstrating an effective balance between in‐plane stiffness and out‐of‐plane bending resistance for Type‐V geometry. However, at 3 wt.%, agglomeration of GNPs leads to a decrease in strengths, reducing UTS to 546 MPa and flexural strength to 123 MPa. Fractography analysis via FE‐SEM also indicates that a 2 wt.% dispersion of GNP enhances interfacial bonding, mechanical strength, and gas impermeability qualitatively (25%–38%) by reducing micro‐voids through a crack‐arresting network formed by continuous macro (PE) barriers and micro (GNP) inclusions.