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Rheological study of gel phenomena during epoxide network formation in the presence of sepiolite
Author(s) -
Nohales Andrés,
López Daniel,
Culebras Mario,
Gómez Clara M
Publication year - 2013
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4321
Subject(s) - gel point , sepiolite , rheology , materials science , epoxy , epoxide , polymer , thermosetting polymer , composite material , chemical engineering , polymer chemistry , organic chemistry , catalysis , chemistry , engineering , raw material
The dynamic behaviour during the crosslinking of an epoxy polymer near the gel point was monitored using rheological multiple frequency experiments. The influence of a needle‐shaped inorganic nanofiller, sepiolite, either non‐modified or organically surface modified during the cure process in the presence of an aliphatic and an aromatic hardener was investigated. The validity of various criteria for determining the gel point was examined for the crosslinking of these filled thermosets. The Winter–Chambon criterion at the gel point is obeyed by the unfilled and by the non‐modified sepiolite‐filled epoxy matrix with either of the two hardeners. However, physical gels are formed in the presence of the organically modified sepiolite and the Winter–Chambon criterion is not valid. For all the systems investigated, the nanofiller reduces the time to reach gelation. Critical relaxation exponents and gel strength have been determined indicating a more elastic and stronger gel in the presence of the aliphatic hardener. © 2012 Society of Chemical Industry