Effects of Water, Salt Solution and Simulated Concrete Pore Solution on the Properties of Composite Matrix Resins Used in Civil Engineering Applications.
Effects of Water, Salt Solution and Simulated Concrete
Pore Solution on the Properties of Composite Matrix
Resins Used in Civil Engineering Applications.
(718 K)
Chin, J. W.; Aouadi, K.; Haight, M. R.; Hughes, W. L.;
Nguyen, T.
Polymer Composites, Vol. 22, No. 22, 282-298, April
2001.
Keywords:
water; concretes; composite materials; resins; civil
infrastructure; concrete pore solution; isophthalic
polyester; polymer composites; salt solution; vinyl
ester
Abstract:
One of the obstacles hindering the acceptance of polymer
composites in civil engineering applications is the
susceptibility of the polymeric matrix to degradation
that is initiated by moisture, temperature, and
corrosive chemical environments. The objective of this
study was to characterize chemical and physical changes
in polymer matrix resins following exposure to these
environments. Resin systems studied were vinyl ester and
isophthalic polyester, both of which are proposed for
use in construction applications. Unreinforced free
films were exposed to water, alkaline and saline
environments at ambient and elevated temperatures for
extended periods of time. Changes in strength and
thermophysical properties were evaluated through tensile
testing, dynamic mechanical thermal analysis (DMTA) and
thermogravimetric analysis (TGA). Chemical degradation
of the polymers was characterized using Fourier
transform infrared (FTIR) spectroscopy. Energy
dispersive x-ray (EDX) analysis of specimens following
exposure was carried out to determine if ion diffusion
into the bulk polymer occurred. Only minor changes in
the glass transition temperatures of the polymers were
observed after prolonged exposure at elevated
temperature, but more substantial changes were noted in
tensile strength, particularly in the case of the
isophthalic polyester. Examination of the polymers
following immersion in salt solution and alkaline
solution showed essentially no ionic penetration into
the bulk, with the exception of specimens that were
visibly degraded. Spectroscopic analysis of chemical
structure prior to and following exposure revealed
varying degrees of ester hydrolysis.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899