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Viscoelastic properties of Japanese lacquer film
Author(s) -
Obataya Eiichi,
Umemura Kenji,
Norimoto Misato,
Ohno Yoshitaka
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(19990829)73:9<1727::aid-app13>3.0.co;2-l
Subject(s) - lacquer , polymerization , viscoelasticity , polymer chemistry , relaxation (psychology) , shrinkage , materials science , atmospheric temperature range , pyrolysis , dynamic mechanical analysis , polymer , composite material , dynamic modulus , chemistry , thermodynamics , organic chemistry , coating , psychology , social psychology , physics
The storage modulus ( E ′) and loss modulus ( E ″) of Japanese lacquer films were measured over a temperature range of −150 to 400°C. Three relaxation processes labeled α, β, and γ were detected at 80, −60, and −140°C, and their apparent activation energies (Δ E ) were 63–91, 13, and 9 kcal/mol, respectively. These were attributed to the micro‐Brownian motions of polymerized urushiol, the molecular motion related to the absorbed water, and the motions of methylene groups in the side chains, respectively. With aging at room temperature, the location of the α peak shifted to higher temperature and its Δ E value decreased. This result was ascribed to the autoxidative polymerization of urushiol. The E ′ of lacquer films increased with heat treatments at 100°C or above. When treated at temperatures below 200°C, the location of the α peak shifted to higher temperature, with a reduction in the Δ E value. Heat treatments at 200°C or above resulted in remarkable shrinkage and weight loss of films owing to the pyrolysis of lacquer constituents. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1727–1732, 1999