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Mechanical energy losses in commercial crosslinked low‐density polyethylene in the temperature range between 200 and 400 K
Author(s) -
Lambri Osvaldo Agustín,
Bonifacich Federico Guillermo,
García José Ángel,
Giordano Enrique David Victor,
Zelada Griselda Irene,
Sánchez Fernando Ariel,
Mocellini Ricardo Raúl,
Plazaola Fernando
Publication year - 2019
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/app.47605
Subject(s) - grain boundary , differential scanning calorimetry , activation energy , materials science , crystallite , amorphous solid , polyethylene , relaxation (psychology) , atmospheric temperature range , thermogravimetry , composite material , polymer , polymer chemistry , crystallography , thermodynamics , chemical engineering , microstructure , chemistry , physics , metallurgy , psychology , social psychology , engineering
Aging treatments in water and in air and controlled neutron irradiation were performed on commercial crosslinked low‐density polyethylene (XLPE) for promoting different mesostructural arrangements of crystallites and crosslinking degree. Infrared spectroscopy, differential scanning calorimetry, differential thermal analysis, thermogravimetry, and dynamic mechanical analysis were used as characterization techniques. The relaxation peak related to the mobility of the grain boundaries from crystalline zones in XLPE was identified at around 260 K (at 7 Hz), involving an activation energy of 90 ± 4 kJ mol −1 . The usual equation for describing the grain boundary mobility in metals involving the movement of grain boundary dislocations was adapted for studying the mobility of the boundaries among the crystalline zones, successfully. In addition, a new mechanical relaxation peak that appears at around 300 K (at 7 Hz), which involves an activation energy of 94 ± 5 kJ mol −1 , was found. The driving force controlling this peak was determined as the dragging of the polymer chains at the amorphous zones adjacent to the crystals controlled by the mobility of the crystallites boundaries. The chains movement was done with break away from the physical pinning points. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47605.