Linear Low‐Density Polyethylene Clay Nanocomposites for Use in Type IV Liner Fabrication for Compressed Gaseous Storage

Compressed gaseous hydrogen storage represents a critical enabling technology for fuel cell vehicles. In this study, linear low‐density polyethylene (LLDPE)–based nanocomposites reinforced with organically modified montmorillonite (OMMT) clay were prepared for potential use in Type IV cylinder liner fabrication. Composites were fabricated via twin‐screw extrusion using a two‐pass protocol at 220°C, notably without compatibilizer addition. Structural and property evaluations were carried out using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results demonstrated a substantial enhancement in the elastic modulus of LLDPE, reaching 1.2 GPa. Moreover, the maximum degradation temperature increased by up to 45°C at a clay loading of 10 wt.% after the second extrusion pass. These enhancements rival those of conventional engineering polymers and demonstrate that LLDPE–OMMT nanocomposites can achieve dimensional stability requirements for filament winding of Type IV cylinders, supporting their evaluation as cost‐effective alternatives to engineering plastics in hydrogen storage applications. However, barrier performance validation through hydrogen permeability testing remains essential before practical implementation.