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Hybrid nanocomposites are a class of materials with exceptional properties due to the synergizing effect of individual fillers. Current work reports the tribological behaviour of high densitypolyethylene-(HDPE) reinforced with 1D-(Multi walled carbon nanotubes-(MWCNTs) and 2D-(h-Boron Nitride nanoplatelets-(BNNP) nanofillers. MWCNTs and BNNPs are chemically modified prior to solution deposition on HDPE and then processed through injection moulding. Testing was performed by varying Load, Speed and Sliding distance for all samples. Parameters such as wear volume, static and kinetic friction co-efficient, surface roughness in steady state and run-in phases, hardness, plasticity index and thermal expansion coefficient were reported. The wear volume of 0.1BNNP composite has shown reduced values as compared to 0.1MWCNTfor all parameters of testing. Highest wear resistance is exhibited by HDPE/0.25MWCNT/0.15BNNP hybrid nanocomposite. Plasticity index was reduced by 40% for HDPE/0.25MWCNT/0.15BNNP sample. The surface roughness increased with speed and sliding distance, while reduced with increasing load. Static and kinetic friction coefficients were also estimated. The surface morphology was examined at the end of Run-in and Steady state to identify prominent wear mechanisms. It is concluded that BNNP based composites possess better properties compared to MWCNT for equal loading, however, Hybrid composites of 1D/2D nanofillers has been shown superior properties.

High Density Polyethylene (HDPE) exhibits good mechanical properties but poor resistance to wear which impedes its application in low load bearing industrial components. The current work is focused to understand the influence of contact pressure on the tribological performance of multidimensional carbon based filled HDPE hybrid nanocomposite. The novelty of the work lies in an in-depth investigation of the contact pressure which is observed to influence the wear performance of HDPE based composites and hybrids. The nanofillers of different dimensions; Nano-diamond (ND)-0D, Multiwalled Carbon Nanotubes (MWCNT)-1D and Graphite Nanoplatelets (GNP)-2D were chosen as reinforcements. The individual role of nanofillers and its response to the contact pressure and the prominent wear mechanisms exhibited thereof were studied in detail. 0.1 GNP/ND was noted to exhibit least contact pressure with highest wear resistance and the dictum was exonerated with Tanδ~0.5 confirming its damping abilities thereby pronouncing more wear resistance. The presence of ND in HDPE had strongly influenced the wear performance and it was analyzed based on electron affinity hypothesis. It was concluded that correlating contact pressure with wear volume, and related wear mechanisms of polymeric materials would be a novel contribution in the relevant field.

Ultra high molecular weight polyethylene (UHMWPE) was reinforced by chemically treated multi walled carbon nanotubes (MWCNTs) up to 2.0 wt% and later subjected to gamma irradiation up to 100 kGy dose. The influence of MWCNTs on the hardness and wear resistance of UHMWPE was evaluated before and after the irradiation process. The hardness of UHMWPE was increased by 89% by homogeneous dispersion of 2 wt% MWCNTs and 100 kGy irradiation. Wear studies on the test samples revealed that the wear volume of unirradiated UHMWPE was reduced by 31%, 54% and 73% upon dispersing 2 wt% MWCNTs, 100 kGy irradiation and the combination of both, respectively. The surface morphology and topography of the wear tracks were examined to understand the wear mechanisms of UHMWPE and its composites. Though the wear mechanism observed in the polymer and composites under normal and irradiated condition is found to be the same, the severity of wear was found to be reduced for irradiated composites compared to unirradiated UHMWPE. The crosslink density (CLD) of composites was found to be higher than that of UHMWPE. It is concluded that the cumulative effect of the presence of MWCNTs and irradiation effectively increased the wear resistance of UHMWPE.