Thermal Tunable Tribological Behavior of Shape Memory Biphenyl Epoxy Resin

Abstract

Although polymer-based self-lubricating materials have rapidly developed recently, intelligent lubricating materials with self-adaptable lubrication with external conditions changing are highly demanded, especially for harsh conditions. Herein, a shape memory epoxy resin based on the biphenyl units (BPEP) with tunable tribological behavior was systematically studied. X-ray diffraction (XRD), field emission scanning electron microscope (SEM), laser confocal three-dimensional profiler, and optical microscope were applied to analyze the friction and wear mechanism. Due to the presence of the specific biphenyl structural units, which could be performed a switching phase between crystalline and amorphous, that allows the self-assembly of the polymer chain under π–π interaction. As a result, the improving mechanical properties enable the BPEP to perform outstanding self-lubricating in a wide temperature range, and the friction coefficient (COF) can be tuned in a wide range of 0.10~0.175 by adjusting the temperature. The shape memory effect of the polymer refers to modulus changing and heat conversion during the shape morphing, and a thermal tunable tribological was observed based on the physicochemical properties varying of polymer with temperature changing. The shape memory effect of BPEPs drives the wear self-compensation so that a low wear rate (6.94 × 10−5 mm3 N−1 m−1) at 110 °C was obtained. The superb lubricating properties of this BPEP could broaden the application scope of shape memory polymers in the field of intelligent lubricating materials, and it is expected to guide future studies on the thermal regulating of tribological behavior.

Toward 4D Printing of Shape Memory Polymers Based on Polyaryletherketone/NVP/PEGDA through Molecular Engineering and Direct Ink Writing 3D Printing

“…However, it was found that PAEK exhibited a specific strain reduction after each shape memory cycle. In other words, dynamic mechanical cycling might cause the benzene ring units in PAEK to reassemble with π–π interaction forces along the stretching direction, resulting in R r values greater than 100% for all PAEK samples as a consequence. , This finding was similar to mechanically responsive self-growing hydrogels which could be made stronger by repeated mechanical stresses that induced physical or chemical structure changes within the polymer . Based on the above investigation, a spring-shaped sample made of P5 was utilized to illustrate the shape memory effect with a greater deformation (Figure g, Video S1).…”