HDPE crystalline lamellae in composites involving pyrolytic carbon black: Effect on elastic modulus

Abstract In order to predict the mechanical behavior of particle reinforced polymer composites, it is crucial to study changes in polymer phase distribution upon interaction with the load in the undeformed state. In this work, HDPE composites reinforced with pyrolytic carbon black (rCBNF) particles, including some rCB modified by mild air oxidation (rCBF), which enabled the aggregation of residual chemisorbed rubber at the surface, examined in a previous work. The development of lamellar morphology induces conformational behaviors resulting from interactions fillers/polymer chains. These interactions cannot be determined by DSC alone but involve short‐range FTIR and Raman and long‐range XRD models. The Raman crystalline content of HDPE was significantly reduced by the presence rCBFs and N330, which varied with lamellar morphology. This process involves the displacement of crystalline lamellae into sublayers by nucleation and crystal growth, resulting in the release of linker molecules, limiting entanglement and improving the elastic properties of the amorphous phase. A significant amount of amorphous phase was produced with N330 and oxidized rCBFs, in which the carbon surface was free of residual rubber. Mechanical tensile tests showed an improvement in the elastic modulus of composites containing these fillers. Highlights N330 and oxidized rCBFs have surface free of the residual rubber contained in rCBNF. Significant reduction in the Raman crystallinity of HDPE with rCBF and N330. Reduction varies with lamellar size through nucleation and crystal growth. Strong release of the tie molecule improves the elastic modulus of HDPE/rCBF. Improved mechanical tensile properties of HDPE/rCBF and HDPE/N330.