Mechanism of <scp>PE</scp> Wax Affecting Biaxial Stretching of High‐Density Polyethylene Films

ABSTRACT To address the issue of a low biaxial stretching ratio in high‐density polyethylene (HDPE), this study employed PE wax as a blending modifier for HDPE film modification. HDPE/PE wax thick films with different contents were prepared via extrusion casting, and their maximum biaxial stretching ratio was analyzed using a biaxial stretching machine. Characterization methods such as X‐ray diffraction, small‐angle scattering, and differential scanning calorimeter were adopted, combined with the Mo Zhishen method, to analyze the non‐isothermal crystallization kinetics of the HDPE/PE wax films. Torque and dynamic rheology reveal that PE wax regulates entanglement density and relaxation behavior, linking melt topology to cavitation suppression and enhanced biaxial stretch stability. The results revealed that the Wax8 film with an HDPE/PE wax mass ratio of 92/8 exhibited the highest biaxial stretching ratio of 5 times. The lubricating effect of the PE wax effectively reduced the interaction force between the molecular chains during biaxial stretching, which enhanced the segment mobility of molecular chains, promoted the orientation and rearrangement of the molecular chains, and rendered the grain size distribution more uniform. The Wax8 film achieved a good balance between the crystallization rate, lamellar thickness, and amorphous region thickness, resulting in excellent comprehensive performance.