Influence of aramid fabric on fretting wear performance of polyetherimide composite - Polyimides and Other High Temperature Polymers - page 510

components; flanges; seals, etc [1, 2]. As a matter of fact, along with adhesive,
abrasive and fatigue mechanisms, the fretting also contributes to a significant ex-
tent in the total wear mechanisms, though its extent of contribution depends on
the various operating conditions. Polymers and composites are extensively used in
the tribo-situations where, most of the time, vibrations are inevitable. The com-
posite or a matrix which performs well in a particular wear mode may not exhibit
similar behaviour in other wear modes. In fact, it can also show deterioration in
performance. Hence, the tribo-performance has to be evaluated in a particular
wear mode. The research on polymer fretting was initiated from the need to en-
hance the fretting performance of the metals by employing thin coatings or films
of polymers on the metal substrates [3, 4]. Kang and Eiss [5] selected a series of
siloxane modified polyimide (PI) copolymers with the aim to study the influence
of siloxane content, humidity and type of substrate on the fretting wear life of the
coatings. Later the efforts were focussed on investigating wear of polymers and
their composites in the form of contacting bodies themselves rather than the films
[6, 7]. Thus the literature survey on fretting wear of polymers and composites re-
veals the fact that the influence of fillers in particulate and fibrous forms is more
unpredictable as compared to the unidirectional sliding wear mode, because of
difference in wear mechanisms.
Polyetherimide (PEI) is a high performance engineering thermoplastic polymer
(Tg 218 ° C and m. p. 380 ° C) with a very good combination of mechanical and
electrical properties along with easy injection mouldability. Its short fibre rein-
forced and solid lubricated composites have exhibited excellent tribo-potential in
sliding wear mode [8] but very little has been reported on fretting wear perform-
ance of these composites [9]. Renicke . [9] investigated the influence of poly

(tetrafluoroethylene) (PTFE) solid lubricant on friction and wear of short glass fi-
bre (30%) reinforced PEI composite. Hardly any literature is available on the fret-
ting wear performance of fabric reinforced composites of PEI. The authors have
reported the influence of carbon fabric on fretting wear performance of two-
directional composites of PEI [10]. In this paper, the influence of aramid fabric on
the fretting wear performance of PEI is presented.

et al

2. EXPERIMENTAL

2.1. Fabrication of composite
The PEI was supplied by GE Plastics USA (properties shown in Table 1) in both
granular and moulded (dumbbell shape) forms. High impact aramid fabric (Kevlar
29) was procured from Tory Industries Inc, Germany. The yarn counts in warp
and weft were 1300 and 1350, respectively. The aramid fabric composite was
prepared using hand lay-up prepreg technique followed by compression mould-
ing. The fabric was cut into 30 cm × 30 cm plies. Twenty four plies of aramid fab-
ric were weighed and PEI resin (40% of the weight of plies) was dissolved in
equal amount (vol.%) of solvent (dichloromethane) overnight. The fabric was