Practical use of intrinsic viscosity for polyethylenes

✍ Scribed by H. M. Quackenbos

• Publisher: John Wiley and Sons
• Year: 1969
• Tongue: English
• Weight: 508 KB
• Volume: 13
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1969.070130207

✦ Synopsis

Although usually derived from measurements at several concentrations, intrinsic viscosity (IV) can be determined with good precision from a single measurement. IV tends to be a regular and distinct function of melt index (MI) for each family of high-density polyethylenes. The tendency to regularity suggests a use in routine control, uniform production being marked by a small scatter about the IV-MI line. The distinctiveness marks one family of medium high and high-density resins from another, and becomes a rapid means of identifying the production method of a resin. Further, IV a t a given M I correlates roughly with properties, and can be used to characterize a resin. These a& tributes of the IV-MI relationship arise from the correlation of IV a t a given M I with width of molecular weight distribution. Such width varies considerably among commercial high-density polyethylenes, causing a commensurate variation in IV. Among low-density polyethylenes the IV-MI relationships is less useful, being confused by long-chain branching.