Ringed spherulite deformation and multiple‐order light scattering from ringed spherulites

Films of low molecular weight linear (LMWL) polyethylene, low molecular weight poly(ethylene adipate), and medium molecular weight linear (MMWL) polyethylene, all of which contained ringed spherulites, were studied by photographic light scattering and by photomicroscopy. The wide‐angle crossed polarizer scattering pattern was observed to consist of a set of arcs if the sample contained uniform well ordered rings, while a diffuse circle was observed as a scattering pattern if the sample contained poorly ordered rings. The first known multiple‐order crossed and parallel polarizer scattering patterns were obtained from samples of LMWL polyethylene and samples of poly(ethylene adipate). Such scattering patterns were not predicted by the theory of Stein and Rhodes for scattering from ringed spherulites. Analysis of these patterns indicates that they are second‐ and third‐order scattering patterns characteristic of the ring spacing. The angular positions of the maxima can be predicted by a generalization of the equation for first‐order ring scattering. The technique of photographic light scattering was also used to study the deformation of ringed spherulites in films of MMWL polyethylene. Results of the light‐scattering measurements indicate that accompanying spherulite deformation there is an increase in the twist distance (and, hence, the ring spacing) of those spherulite fibrils in the direction of tensile stress, and a decrease in the twist distance of those fibrils at right angles to the stress direction. The data are presented and discussed in terms of current theories of spherulite deformation.