The hot compaction of SPECTRA gel-spun polyethylene fibre

Abstract

The compaction of gel-spun high molecular weight polyethylene (PE) fibre, SPECTRA 1000, has been investigated for a range of compaction temperatures between 142 °–155 °C. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and broad-line nuclear magnetic resonance (NMR) techniques have been used to examine the structure of the compacted materials and to determine the compaction mechanisms. With increasing compaction temperature, the flexural properties of the compacted materials did not show any significant change up to 154 °C, but large changes were observed if the temperature was increased from 154 to 155 °C. DSC and SEM studies revealed that no evident surface melting and recrystallization occurred during hot compaction in the temperature range 144–154 °C, although the rigid crystalline fraction measured by NMR for all compacted materials is significantly lower than that for the original fibre. Significant transverse strength is also developed at the lower compaction temperatures, and this also only markedly increases on going from 154 to 155 °C. Structural investigations show how the fibres deform so as to interlock, and localized welding occurs, so as to bond each fibre to its neighbour. This is distinct from the melting and recrystallization at the surface of the fibres previously observed in melt spun fibres.