The molecular structure of polyethylene. XI. Weight- and number-average molecular weights of selected samples

✍ Scribed by Kokle, V. ;Billmeyer, F. W. ;Muus, L. T. ;Newitt, E. J.

• Publisher: John Wiley and Sons
• Year: 1962
• Weight: 576 KB
• Volume: 62
• Category: Article
• ISSN: 0022-3832
• DOI: 10.1002/pol.1962.1206217319

✦ Synopsis

Abstract

Improved methods for measuring weight‐ and number‐average molecular weight of polymers soluble only at elevated temperatures are applied to selcted samples of polyethylene. For two samples of essentially linear polyethylene, number‐average molecular weights by cryoscopy are 11,500 and 13,000, and weight‐average molecular weights by light scattering are 144,000 and 175,000. For samples of branched Fawcett‐type polyethylene, number‐average molecular weights are in the range 10,000–19,000 and weight‐average molecular weights are between 300,000 and 700,000. For one sample each of branched and essentially linear polyethylene it is demonstrated that light scattering measurement in three solvents gives the same molecular weight: no evidence is found for the “association” of these samples of polyethylene in thermodynamically poor solvents. It is thus demonstrated that association is not observed for all samples of polyethylene in dilute solution in α‐chloronaphthalene.