Compressional behaviour of Kevlar fibres

A model for the compressive buckling of extended chain polymers

“…An example of kink banding in axially compressed Kevlar* fibers is shown in Figure 1. These compressive kink bands have been observed for well-oriented polymers based on both rigid rod [1][2][3][4][5][6] and flexible [7][8][9][10][11][12][13][14][15] chains. Most of these polymers exhibit nearly linear elastic behavior in compression until the onset of kink banding.…”

Polymer applications

“…The structure of the aramid fibers has been studied by Dobb and Johnson [447,[473][474][475][476][477] and summarized by many others [406,415,[417][418][419]478]. Dobb et al [473] first showed a lattiee image for fibrillar fragments produced by sonica- Fig.…”

“…The fracture mechanism in fatigue reflects poor compressive properties [480,481,483] as failure is transverse to the fiber axis. Dobb et al [477] studied the compression behavior of aramid fibers by SEM and TEM and proposed a mechanism for the formation of kink bands consistent with a loss of tensile strength after compression. SEM of composite fracture surfaces shows transverse failure and fiber splitting (Fig.…”

A Comparative Analysis of Techniques Used to Estimate the Mean Recoil Compressive Strength of High Performance Polymers

“…There are several indirect methods proposed to measure the compressive strength of high performance polymers. Bending techniques (ASTM D 3375-79, ASTM D 695, ASTM D 3410, ASTM M 695) are employed to estimate a fibers compressive strength [5,[13][14][15][16]. While the bend test does provide a comparison in results to the composite test, the compressive strength found is generally much higher, by two or three times, to the compressive strength found by the composite test.…”

“…With this spinning technique comes a dramatic reduction in the fiber's ability to distribute a compressive load [2]. For example, Kevlar (poly p-phenylene terephthalamide or PPTA) fiberreinforced composites typically possess compressive strengths that are more than five times less than their tensile strengths [3][4][5]. Figure 1 depicts the repeat unit of Kevlar.…”