IPN-PUA: An ultra-low density self-lubricating composite with IPN structure–liquid lubricant coupling mechanism

The goal of net zero carbon emission is of a great concern to energy conservation and emission reduction. In aerospace and other industrial fields, one of main energy consumption forms is the friction between the motion pairs despite that energy consumption caused by equipment mass cannot be ignored. Therefore, ultra-low density self-lubricating composites with interpenetrating network (IPN) structure-liquid lubricant coupling mechanism is designed and prepared in this work to meet the pressing requirement of energy saving and emission reduction. The liquid lubricant is in situ locked into polyurethane acrylate (PUA) IPN structures (IPN-PUA structures). The thermodynamic, mechanical, and tribological properties, as well as the density-friction comprehensive properties of the material with IPN-PUA structures was studied. After locking the liquid lubricant into IPN-PUA structures, the material possesses not only excellent self-lubricating properties but also good micro-mechanical properties with the coefficient of friction (COF) of 0.0938, the wear rate of 6.58×10^-15 m³/(N•m) and nanoindentation modulus of 4.5 GPa. Such composite materials also possess an ultra-low density of 1.107g/cm³, which contributes to their excellent versatile self-lubrication and low-density characteristics when compared with other polymeric materials.