Abstract
Polytetrafluoroethylene (PTFE) is provided with excellent self-lubricating properties and corrosion resistance. However, the lower thermal resistance greatly limits its high-temperature applications. In the present work, two types of fillers with rigid organic polymers and submicron-sized inorganic hexagonal boron nitride (h-BN) were added to the PTFE matrix. The microstructure and thermal–mechanical properties of PTFE-based composites with different filler types or ratios were comparatively investigated. The results suggested that the polyphenyl ester (POB)/h-BN co-filled PTFE composites exhibited excellent thermal–mechanical properties compared with the polyimide (PI)/h-BN/PTFE materials at high temperature. The optimal ratios of POB and h-BN were 25 wt.% and 5 wt.%, respectively. The Vicat softening temperature of 25 wt.% POB/5 wt.% PI/PTFE composite increased by 41.3% compared to that of pure PTFE, which was due to the cross-linked reticulation structure with regularly distributed pores and higher crystallization degree. The storage modulus increased from 51.99 MPa to 685.76 MPa at 260 °C and reached 187.82 MPa at 320 °C. The uniform distribution of anisotropic orientation of the h-BN flakes showed an obvious pinning effect, and further improved the thermal–mechanical stability of POB/h-BN/PTFE composites.
Highlights
As a high-performance engineering material, polytetrafluoroethylene (PTFE) with good thermal stability, chemical resistance and self-lubricating properties has been widely applied in many important parts, such as gear, bearing, pulley, guide rail, piston ring, and sealing elements [1,2,3]
In order to reduce the agglomeration of hexagonal boron nitride (h-BN) powder and improve the interfacial compatibility with PTFE matrix, a KH560 coupling agent was added into a solution
For the mixed powder with 25 wt.% POB and 5 wt.% h-BN, as shown in Figure 2f, it was observed that the POB particles were homogeneously distributed in the powder
Summary
As a high-performance engineering material, polytetrafluoroethylene (PTFE) with good thermal stability, chemical resistance and self-lubricating properties has been widely applied in many important parts, such as gear, bearing, pulley, guide rail, piston ring, and sealing elements [1,2,3]. It is of importance to explore an effective method to enhance the softening resistance and mechanical properties of PTFE. The hybrid modification of single-/multi-component fillers via the molding process is usually used to improve the thermal–mechanical properties of PTFE. Multi-component inorganic nano-fillers are often used to improve the softening resistance of PTFE. ZrO2 and Au nano-particles served as friction modifiers to reinforce the friction and wear properties of PTFE [11,12].
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