Detection of divergences in polyethylene resins fabrication by means of the modified stepwise isothermal segregation technique

Autor: D. Rousselot, D. Gueugnaut
Rok vydání: 1999
Předmět:
Zdroj: Journal of Applied Polymer Science. 73:2103-2112
ISSN: 1097-4628
0021-8995
DOI: 10.1002/(sici)1097-4628(19990912)73:11<2103::aid-app6>3.0.co;2-e
Popis: The selective crystallization behavior of a series of commercial medium- and high-density polyethylene resins has been studied by means of an original modified procedure of the stepwise isothermal segregation technique using differential scanning calorimetry. The technique consists of a sequenced multiple-stage stepwise thermal treatment of the materials allowing separation of the macromolecules with respect to their length-to-branching content and distribution. It is assumed that such a separation process gives an image of the proportion of specific crystallizable species, which are in turn responsible for slow crack growth resistance of the resins under study. A drift molecular parameter is calculated from a combination of the crystallization data at 119°C and 114°C. This molecular parameter is capable of revealing some divergences regarding the fabrication of a commercial polyethylene resin within a decade. Such divergences are well correlated with premature brittle failures under hydrostatic pressure testing of a series of correctly extruded pipes. Furthermore the drift molecular parameter allows a ranking of different medium- to high-density polyethylene resins—the lower this parameter the better the slow crack growth resistance of the materials. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2103–2112, 1999
Databáze: OpenAIRE
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