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Detection of divergences in polyethylene resins fabrication by means of the modified stepwise isothermal segregation technique
Author(s) -
Gueugnaut D.,
Rousselot D.
Publication year - 1999
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19990912)73:11<2103::aid-app6>3.0.co;2-e
Subject(s) - polyethylene , differential scanning calorimetry , materials science , isothermal process , fabrication , crystallization , high density polyethylene , low density polyethylene , branching (polymer chemistry) , composite material , polymer chemistry , thermodynamics , medicine , physics , alternative medicine , pathology
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