Mechanical behavior of high density polyethylene and its carbon nanocomposites under quasi-static and dynamic compressive and tensile loadings

The main objective was to characterize and compare the tensile and compressive mechanical behavior of polymer nanocomposites under both quasi-static and dynamic compressive and tensile loadings. The materials studied included HDPE (high density polyethylene), HDPE/CNF (carbon nanofiber) and HDPE/CNF-GNP (graphite nanoplatelet). Microstructure analyses were also conducted to gain insight into the possible deformation and fracture mechanisms for the observed macroscopic mechanical behavior. The tensile strengths were observed to be lower than the corresponding compression strengths under dynamic loadings, but higher under static loadings. Regarding the strengthening effects due to nanofillers, it was observed that addition of GNP appeared to have somewhat reduced the compressive strength, but improved the tensile strength. Possible mechanisms for the observed tension-compression asymmetry exhibited by both the macroscopic behavior and the reinforcement effects are discussed.