THE HOT COMPACTION OF SPECTRA GEL-SPUN POLYETHYLENE FIBER

The compaction of gel-spun high molecular weight polyethylene (PE) fib re, SPECTRA 1000, has been investigated for a range of com paction tem peratures between 142 degrees-155 degrees C. Differentia I scanning ca lorimetry (DSC), scanning electron microscopy (SEM) and broad-line nuc lear 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 prope rties of the compacted materials did not show any significant change u p to 154 degrees C, but large changes were observed if the temperature was increased from 154 to 155 degrees C. DSC and SEM studies revealed that no evident surface melting and recrystallization occurred during hot compaction in the temperature range 144-154 degrees C, although t he rigid crystalline fraction measured by NMR for all compacted materi als is significantly lower than that for the original fibre. Significa nt transverse strength is also developed at the lower compaction tempe ratures, and this also only markedly increases on going from 154 to 15 5 degrees C. Structural investigations show how the fibres deform so a s to interlock, and localized welding occurs, so as to bond each fibre to its neighbour. This is distinct from the melting and recrystalliza tion at the surface of the fibres previously observed in melt spun fib res.