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Two‐step degradation of high‐density polyethylene during multiple extrusion
Author(s) -
Epacher Edina,
Tolvéth János,
Stoll Klaus,
Pukánszky Béla
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(19991107)74:6<1596::aid-app35>3.0.co;2-d
Subject(s) - degradation (telecommunications) , extrusion , high density polyethylene , polyethylene , materials science , reactive extrusion , composite material , chemical engineering , computer science , engineering , telecommunications
Abstract Ensuing our recent studies on polyethylene stabilization, 1,2 further multiple extrusion experiments were carried out with a high‐density polyethylene (HDPE) polymer containing various amounts of a sterically hindered phenolic antioxidant. Discoloration, thermoxidative stability, and melt flow index (MFI) retention were measured by standard techniques; the functional group content of the polymer was determined by Fourier transform infrared (FTIR) spectroscopy, and rheological, as well as mechanical properties, were also measured. The results indicated that degradation and stabilization reactions take place according to two different mechanisms in the first and subsequent processing steps, respectively. Color development could be described well by the simple first‐order overall reaction kinetics proposed earlier, and color change could be related to the stability of the polymer. The existence of general correlations among the properties proved that all chemical reactions are interrelated. The reactions of the stabilizer lead to color development, while those of the polymer to a modification of its molecular architecture, which determines the rheological and mechanical characteristics of the product. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1596–1605, 1999