Mechanical, Wear and Thermal Behavior of Polyethylene Blended with Graphite Treated in Ball Milling

Abstract

Additive manufacturing, civil, and biomechanical applications are among the most important sectors, where the filler’s presence can significantly improve the quality of polymeric products blends. The high market demand of new low-cost material to be used as shock absorbers and mechanical joints arouses our curiosity to study a relatively common commercial polymer and filler. The possible improvement by blending high-density polyethylene (HDPE) and graphite was investigated for these sectors. To achieve this objective, we have prepared HDPE/graphite nanocomposites following mechanical treatment to understand which parameter provides the researched properties. As widely reported in the literature, milling treatment leads to the decrease of the particle size and the exfoliation of graphitic layers. Therefore, graphite has been previously treated with a ball mill for different times (1–16 h) to enhance its lubricating action. We checked an improvement in stiffness, yielding strength, thermal stability, and, in particularly, wear resistance that increased by 65% with respect to that of polyethylene (PE). A treatment time of eight hours in ball milling could be enough to give an appreciable improvement. The wear behavior of HDPE with treated graphite has not been deeply investigated so far, and it could be important because HDPE is considered a “carrier polymer” for different low-friction applications.

Tribological Behavior of UHMWPE (Disc) against Ti6Al4V (Pin) under Different Lubrication Conditions

“…The rotation speed was equal to 60 rpm in each test. [ 12 ] Wear tests were performed at room temperature under different conditions: dry, in distilled water or synovial fluids, both synthetic (SSF) and natural bovine (BOV). Upon visual inspections after testing, the pin appeared intact (Figure 1c), possibly with polymer residues on the tip in the case of dry conditions (Figure 1d).…”

Experimental Investigation of the Tribological Contact between Ti6Al4V-EBM Pin and UHMWPE Rotating Sheet for Prosthetic Applications

“…Among the most suitable polymeric materials for prosthetic joints, ultra-high molecular weight polyethylene (UHMWPE) is considered, thanks to its excellent physical, chemical and mechanical characteristics, such as biocompatibility and good resistance to wear and abrasion, which can be increased by appropriate reinforcers as reported in the review by Macuvele et al [4] and in more recent articles [5][6][7] concerning the use of carbon nanofiller and graphite. However, wearing contact with metal parts can lead to the release of debris, limiting the use of UHMWPE.…”