The effect of vinyl concentration on the structural and rheological characteristics of peroxide modified high-density polyethylenes

AIREGUAMEN I. AIGBODION; JORGE A. RESSIA; ANDRÉS E. CIOLINO; MARCELO D. FAILLA; ENRIQUE M. VALLÉS

JOURNAL OF APPLIED POLYMER SCIENCE

John Wiley and Sons

Lugar: New York (USA); Año: 2010 vol. 115 p. 1942 - 1951

0021-8995

The effect of hydrogenation of the terminal vinyl groups on peroxide modification and rheological properties of high-density polyethylene (HDPE) was investigated. The aim of the study was to determine exclusively, the effect of terminal vinyl groups on peroxide crosslinking and rheological properties of HDPE using one polymer type. This was achieved by hydrogenation of the terminal vinyl groups of a commercial HDPE to obtain an identical material from a structural point of view, differing only in the nature of the terminal unsaturations, and comparing its level of peroxide crosslinking with that of the original polymer. Hydrogenated and unhydrogenated polymer samples were modified at 170 C with different amounts of organic peroxide ranging from 125?5,000 ppm. Changes in the molecular structure were determined by FTIR, SEC and rheological measurements. Hydrogenation of the terminal groups of the original polymer significantly reduced the rate of modification or crosslinking. Dynamic viscosity and elasticity increase with the level of peroxide modification. Unhydrogenated samples exhibit a rapid increase in viscosity and elastic modulus while their hydrogenated counterparts require about 500% of the amount of peroxide needed for the unhydrogenated sample to attain similar structural changes.