Small Angle Scattering Study of Polyethylene Crystallization from Solutions

Abstract

Crystallization of low molecular weight polyethylene from concentrated solutions has been studied using small angle neutron scattering (SANS). The detection sensitivity of the volume fraction degree of crystallinity is estimated to be 10 −5 , allowing for measuring the structure and kinetics during the very early stages of crystal growth. SANS spectra for both the early and late stages of crystallization can be satisfactorily interpreted with a lamellar crystal model; there is no evidence of diverging or spinodal-decomposition-like density fluctuations during the early stage of crystallization in polyethylene solutions. A possible explanation of the dominant wavevector in small angle x-ray scattering that led to the proposal of "spinodal decomposition" mechanism for early stage crystallization is suggested.

A comparison on self-seeding and isothermal crystallization of polyethylene in solution using small angle neutron scattering

“…S 11 and S 33 are the partial structure factors consisting form, structure factors and coil chains. The detail equations involved in isothermal crystallization of polymer in solution are shown elsewhere [12,13]. We are able to modify model eqn.…”

“…Time sequence spectra at different T c were collected with time intervals varying from 1 min to 3 min for each spectrum. Total coherent scattering cross section per unit volume for polymer crystallization in solution as developed is expressed as [12,13,15] …”