Polyester fiber tensile fracture

Figure la. Tensile fracture of a polyester type 54 fiber taken from a heat-set polyester fabric. Sample was fractured at 65% rh and 21 °C (2,665X). 

Conductive reinforcements in thermoplastics are a new application of composites [2891. High temperature resistant thermoplastics, such as PPS, PEI, PPO and liquid crystal polyesters, have been combined with conductive fibers, generally chopped graphite and nickel coated graphite. Fiber distribution, orientation and fracture morphology were determined by optical and SEM techniques. Poor bonding in the nickel coated graphite composite, as observed in SEM tensile fractures, resulted in lowered tensile and impact properties. 

The fracture morphology in tensile fatigue is quite different as shown in the micrographs of a polyamide and a polyester fiber in Fig. 5.8 [44]. The fibrillar nature of a polyamide fiber results in a break with a tail, as seen in the broken ends (Fig. 5.8A, B). The typical fatigue failure has a crack initiated at the fiber surface with radial penetration into the fiber. The crack then runs along the fiber, and finally the fiber... 

The aspect of the flow curves in Fig. 9.6 indicates the predominant condition of the test. For instance. Fig. 9.6a shows uniform serrations (stick-shp) associated with a continuous, step-by-step process of fiber slipping away off the polymeric block. This exclusive pullout mechanism occurred only in the first part of the curve depicted in Fig. 9.5c. In this case, the fiber was intact after the test and, in some cases, covered with a layer of polyester. By contrast. Fig. 9.6d shows a smooth curve up to fracture. In this case, no pullout process occurred, and the fiber had undergone tensile rupture in association with the last horizontal part of the curve. The intermediate condition of both pullout and fiber rupture are shown in Fig. 9.6b, c. 

Sreekumar et al. (2008) have reported the effect of fiber content in polyester composites and have reported 40% volume fraction to show maximum tensile strength. Sapuan et al. (2006) investigated the mechanical properties of woven banana fiber reinforced with epoxy composites. Tensile strength. Flexure, impact and fracture surface study of woven pseudo stem banana fiber reinforced with epoxy composites was reported and the chemical modification of kenaf fiber was carried out by Edeerozey et al. (2007). Anuar et al. (2011) studied the thermal... 

---