Rate mechanism and dislocation generation in high density polyethylene and other semicrystalline polymers

The aim of the paper was to use recent experimental dislocation data for the development and testing of a dislocation mediated strength model based on that introduced by Scogna and Register for semicrystalline polymers. It is shown that the model can successfully describe measured and evaluated data of high density polyethylene (PE-HD) on the flow stress as function of strain rate and temperature. Similar coincidences of model fit with experimental yield stress data from literature for polypropylene and polyethylene-ethylenemethacrylic acid co-polymers (E/MAA) were found which suggests prevailing of dislocation mediated plasticity mechanisms also in these materials. It also turned out that two parameters of the model – namely the dislocation density and the lamella size – are not determined by the molecular chemistry but by the conditions of processing and/or sample preparation. Therefore the model allows for a reliable estimation of the dependence of the yield stress on these conditions.