On the Improved Mechanical Properties of Ball-Milled GNPs Reinforced Short Chain Branched-Polyethylene Nanocomposite: Micromechanical Modeling and Fractography Study

Short-chain branched-Polyethylene (SCB-PE) is commonly utilized in hot and cold piping systems due to its high-temperature resistance. SCB-PE nanocomposites using graphene nanoplatelets (GNPs) as a reinforcing filler were synthesized in this work. The effect of the filler’s content and the ball-milling process on nanocomposites’ structure, tensile and shear properties was studied. Two series of nanocomposites have been prepared, one with and one without the ball-milling as a premixing step prior to the melt-mixing process. The ball-milling process induced a lower crystallinity degree of the SCB-PE nanocomposites than their solely melt-mixed counterpart. The tensile properties of the ball-milled samples presented a more profound enhancement with increasing filler content. The Ji and modified Halpin-Tsai micromechanical models were best fit to describe the experimental elastic modulus of the solely melt-mixed and the ball-milled nanocomposites, respectively. Fractography studies suggested that the detachment of the filler particles from the polymer matrix is avoided for lower GNPs contents of the ball-milled samples. Shear tests revealed that the shear strength increased and ductility decreased with increasing filler content in any case. The ball-milling process resulted in SCB-PE nanocomposites with superior mechanical properties compared to their solely melt-mixed counterparts