The effect of the degree of cure on the corrosion resistance
of vinyl ester/glass ﬁbre composites
, P.J. Burchill
Department of Aerospace Engineering, RMIT University, P.O. Box 3476V, Melbourne 3001, Australia
Platforms Sciences Laboratory, P.O. Box 4331, Melbourne 3001, Australia
Received 18 March 2003; revised 13 August 2003; accepted 22 August 2003
Four different cure schedules were used to determine the effect of the degree of cure on the corrosion resistance of a vinyl ester/glass ﬁbre
reinforced composite. Specimens were immersed in four separate environments: 5 wt% NaOH, 32 wt% HCL, 25 wt% H
, and uncut
Kerosene, each at 66 8C (150 8F). It was found that the degree of cure did not affect the amount of degradation in ﬂexural properties over time.
Rubber-toughening of the resin matrix and the total volume fraction of resin in the composite were found to affect the amount of degradation
exhibited. Sodium hydroxide was the only medium, which produced degradation of the ﬂexural properties after 3 months. For all the other
media, degradation occurred within the ﬁrst 3 months of exposure. The analysis of variance technique provided a useful method for
determining signiﬁcant differences in measured mechanical properties.
q 2003 Elsevier Ltd. All rights reserved.
Keywords: B. Corrosion; B. Mechanical properties; C. Statistical properties/methods; E. Cure
It is common practise in the laminating industry for
composite parts to be cured at room temperature or to receive
only a low-temperature postcure . Under-cure of the resin
will not generally produce optimal tensile properties  and
in applications where corrosive environments are experi-
enced by the material, further degradation of the mechanical
properties can occur. The loss of strength or stiffness over
time can produce unexpected material failure resulting in, at
the very least, costly downtime or hazardous spills.
It was thought that the initial cure of the resin may affect
the extent of degradation in the mechanical properties
during exposure, yet little in the literature examines this
aspect of current industrial practice . The current study
was thus commissioned by Huntsman Chemical Co., The
Defence Science and Technology Organisation and the Co-
operative Research Centre for Polymers (CRC-P), as part of
the CRC-P’s industrial research.
Applications requiring corrosion resistant composite
materials usually use vinyl ester resin as the composite
matrix because these thermosets have high resistance to
2. Materials and methods
The vinyl ester resin used was Hetron 922
. Speciﬁcs of
the resin chemistry are covered by the trademark. The resin
was catalysed with 0.32 wt% cobalt octoate and 1.5%
methylethylketone peroxide (SR grade). Previously, the
optimised cure cycle had been determined as 2 h at 100 8C,
achieving a T
of 83 8C . To have a viable geltime, given
the large area of the laminates, 0.272 wt% t-butyl catechol
(TBC) was added as a retardant (Table 1).
To vary the degree of cure of the resin in different panels,
four different curing schedules were chosen
1. 50 8C for 2 h
2. 50 8C for 2 h, accelerated with dimethylaniline (DMA)
3. 100 8C for 2 h
4. 100 8C for 2 h with DMA.
1359-835X/$ - see front matter q 2003 Elsevier Ltd. All rights reserved.
Composites: Part A 35 (2004) 501–508
Corresponding author. Tel.: þ61-3-99258075; fax: þ61-3-99258099.
E-mail address: email@example.com (A. Kootsookos).