Neutron-scattering studies of bulk polyethylene at intermediate Q values

Abstract
We report SANS studies of bulk polyethylene (PE) samples crystallized from the melt at different rates. All samples contained both protonated and deuterated PE. Substantial isotopic concentration fluctuations are present in slow‐cooled samples. This is seen as large differences in the low‐angle (low‐Q) SANS. At larger Q values, the SANS data from both materials is approximately identical. We interpret this in terms of an exponential radial correlation function for composition fluctuation whose correlation length is comparable to lamellar dimensions. Numerical calculations show that concentration fluctuations have minimal effect in the intermediate Q region.