Polymers have lower resistance to scratching and wear than metals. Liquid lubricants work well for metals but not for polymers nor for polymer-based composites (PBCs). We review approaches for improvement of tribological properties of polymers based on inclusion of fillers. The fillers can be metallic or ceramic—with obvious consequences for electrical resistivity of the composites. Distinctions between effectiveness of micro- versus nano-particles are analyzed. For example, aluminum nanoparticles as filler are more effective for property improvement than microparticles at the same overall volumetric concentration. Prevention of local agglomeration of filler particles is discussed along with a technique to verify the prevention.

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Poly(vinyl chloride) (PVC) is widely used—in spite of HCl formed from it at elevated temperatures. PVC wire and cable insulation has poor thermal stability, causing the plasticizer to separate from the PVC chains and produce an oily residue, lowering the tensile elongation at break and thus increasing brittleness. One uses cross‐linking agents and antioxidants, as well as mixtures of both, to improve the thermal stability of the plasticizer and tensile properties of PVC after thermal exposure. We performed tensile tests, tribological tests, profilometry, scanning electron microscopy (SEM), and water absorption determination before and after thermal exposure at 136 °C for 1 week. After adding the agents, elongation at break increased by 10 to 20% while the wear rate and water absorption were lower than for the control sample. Less voids are seen in the SEM images after adding these two kinds of agents. The thermal resistance of the PVC cable insulation is best enhanced by combinations of cross‐linking agents and antioxidants. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48816.

Two-dimensional layered materials (2DLMs), MoS2 and WS2, and three-dimensional (3D) graphite were infused in thermoplastic polymer matrices comprised of acrylonitrile butadiene styrene (ABS) and polyethylene terephthalate glycol (PETG). Two processing approaches were examined for creating polymer tensile test specimens using the composites for mechanical testing, which included three-dimensional (3D) printing and injection molding. The ductility generally decreased with the addition of the fillers indicated by an increase in Young’s modulus and a corresponding decrease in yield stress and tensile stress for the 2DLM-polymer composites. The dynamic friction data of the composites were measured in an attempt to exploit the solid phase lubricating properties of graphite and the 2DLM fillers. Graphite proved to lower the dynamic friction in the cases of 3D printed PETG and injection molded ABS, while MoS2 and WS2 were found to reduce friction in 3D printed PETG and ABS. Finally, the thermal conductivities of these polymer matrix composites were measured and compared to the pure polymer matrices. The thermal conductivity increased in both ABS and PETG composites containing graphite, MoS2, and WS2, irrespective of their processing routes. The use of 2DLM-based polymer composites remains an area of interest for a wide range of applications in the future, such as wearable electronics and sensors with low-cost additive manufacturing approaches.