SOLUBILITY AND CRYSTALLINITY DATA FOR ETHYLENE POLYETHYLENE SYSTEMS/

Physical property data for the system ethylene/butene/polyethylene are presented for both high and low density polyethylene (PE) samples. A simple Flory Huggins model is shown to be satisfactory for the estimat ion of the solubility (in the amorphous fraction of the polymer) of bo th monomers in PE, with chi equal to 0.3 for ethylene and 0.5 for bute ne. No co-solubility effects of butene on ethylene were found for the relatively low partial pressures of butene used in this study (0.65 ba rs/21 bars). However, DSC analyses of the polymer samples used in the cosolubility experiments showed an irreversible reduction of the overa ll crystallinity after exposure to butene. Crystallinity data as a fun ction of temperature are also presented for a variety of low PE sample s, along with data on the melting point (T-m) as a function of butene content. Both quantities were observed to decrease as a function of in creasing butene content, and an empirical relationship between the but ene fraction of a PE sample and T-m is proposed. (C) 1998 Elsevier Sci ence Ltd. All rights reserved.