We will exploit the unique capability of NIMROD to bring new understanding to the way in which long chain polymers crystallise. There are three key length scales: the first involves the thin (10nm) lamellar crystals, the second are the crystal planes (1nm) and the third is the local chain conformation (0.1nm). The ability to obtain time-resolving scattering data over an extensive Q range which encompasses all these length scales simultaneously brings new light to this long standing problem. We will use neutron scattering to quantify the transformation pathways of these three length scales. We will tightly couple the scattering data to computational molecular modelling procedures developed at Reading to extract quantitative parameters which describe the reorganisation of the polymer chains prior to- and during crystallisation and use these to extend our understanding of crystallisation.