Polyimide Filled PTFE

Polyimide Filled PTFE

Polyimide (PI)

Polyimide (PI) is one of the organic polymer materials with excellent comprehensive performance. It has the characteristics of high insulation, fatigue resistance, high temperature resistance, abrasion resistance, impact resistance, low noise and long service life.

PI Filled PTFE Composite

• PI-filled PTFE composite material has the characteristics of high wear resistance, high and low temperature resistance, self-lubricating, low noise, stable size, and not easy to damage to abrasive objects.

Figure 1. SEM micrographs of fractured surfaces of PTFE and PI filled PTFE [1]

• As an engineering plastic, PI filled PTFE has a slight lack of chemical resistance, which is not resistant to alkalis and hot concentrated acids, nor is it resistant to hydrolysis. However, in the dry friction environment, PI filled PTFE has significantly better wear resistance than similar products of polyphenylene ester reinforced polytetrafluoroethylene, which is especially suitable for dry friction conditions in a non-chemically corrosive environment. The products are mainly used in piston rings, rubber cups for oil-free pumps, bushings, gaskets and other parts.

Table 1. PI filled PTFE composite material performance parameter reference

	Medium filled PI/PTFE
Color	Orange
Density (g/cm3)	2
Shore hardness D	65
Insulation	Non-conductive
Chemical property	Not resistant to alkali and hot concentrated acids, nor resistant to hydrolysis
Tensile strength (MPa)	15.5
Elongation at break (%)	290
Coefficient of friction	0.2
Wear rate	3.0×10^-6 mm3(N·m)^-1

Note: The above data is for reference only. The actual product in use may vary due to different parts size, raw material batch type, and mechanical working conditions. In addition, the filled PTFE is a multi-element composite material, and the proportioning composition can be adjusted according to the actual working conditions of the customer, which is not fixed.

Applications

• PI and carbon fiber filled PTFE can improve the wear resistance of composite materials. Studies have shown that when the appropriate ratio of PI and carbon fiber is added, the wear rate of PTFE-based composites under seawater lubrication will be significantly reduced. This phenomenon means that there is a synergistic antifriction and wear resistance effect between PI and carbon fiber, and the composite material shows the application prospects in the marine environment.

Figure 2. Friction coefficient and wear rate of PTFE and its composites under seawater lubrication [1]

• PI-filled PTFE composites have extremely low friction and are non-abrasive, making them ideal for applications involving softer mating surfaces such as steel, aluminum or other plastics. Therefore, polyimide-filled PTFE is particularly suitable for dry operation and start-stop applications. However, polyimide is an expensive PTFE filler, so you need to consider the cost when choosing it.

Reference

1. Beibei Chen, Jianzhang Wang, Fengyuan Yan, Materials and Design 36 (2012) 366–371.

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