J MATER SCI 41 (2006) 4349–4356
Monitoring of cure kinetic prepreg and cure cycle
modeling
M. L. COSTA
Divis
˜
ao de Materiais/Instituto de Aeron
´
autica e Espac¸o, AMR/IAE/CTA, Prac¸a Mar do Ar Eduardo
Gomes n
◦
50 – Vila das Ac
´
acias, S
˜
ao Jos
´
e dos Campos, SP, Brazil 12228-904
E-mail: mleali@directnet.com.br
E. C. BOTELHO
Fatigue and Aeronautic Material Research Group, Department of Material and Technology,
UNESP, Guaratinguet
´
a, SP, Brazil
E-mail: ebotelho@directnet.com.br
M. C. REZENDE
∗
Divis
˜
ao de Materiais/Instituto de Aeron
´
autica e Espac¸o, AMR/IAE/CTA, Prac¸a Mar do Ar Eduardo
Gomes n
◦
50 – Vila das Ac
´
acias, S
˜
ao Jos
´
e dos Campos, SP, Brazil 12228-904
E-mail: mirabel@iae.cta.br
Published online: 21 April 2006
Cure kinetic model is an integral part of composite process simulation, which is used to predict
the degree of curing and the amount of the generated heat. The parameters involved in kinetic
models are usually determined empirically from isothermal or dynamic differential scanning
calorimetry (DSC) data. In this work, DSC and rheological techniques were used to investigate
some of the kinetic parameters of cure reactions of carbon/
F161
epoxy prepreg and to evaluate
the cure cycle used to manufacture polymeric composites for aeronautical applications. As a
result, it was observed that the
F161
prepreg presents cure kinetic with total order 1.2–1.9.
C
2006
Springer Science
+
Business Media, Inc.
1. Introduction
Curing of the matrix resin is a determining step in man-
ufacturing of fiber-reinforced thermoset composites. The
quality of composites is controlled to a great extent by
the cure cycle parameters such as time, temperature, pres-
sure and their sequence of combination. Traditionally a
composite manufacturer just follows the cure schedule
suggested by the prepregger or the resin supplier. This
schedule is usually determined in an ideal situation where
the resin is still “fresh” and may not be representative to
the actual curing state of the resin in a composite man-
ufacturing facility. The composite manufacturer has to
study the curing behavior of the matrix resin just prior to
autoclave or press curing. This is necessary to verify the
processability and to optimize the cure cycles especially
if the resin has been shelved several times [1–3].
Laboratory tests for processability aims to determine
how a sample performs during a simulated manufacturing
curing cycle. These tests use small quantities of mate-
rial, are fully equipped, and are operated by programmed
∗
Author to whom all correspondence should be addressed.
temperature scanning at a constant heating rate. The role
of processability testing is to define the kinetics of cur-
ing,the limits of thermal stability, and the optimum curing
cycle, which leads to high performance and durability of
the manufactured component. Very often, procedures of
chemical analysis are implemented to verify thermoana-
lytical data and to define the mechanism of curing. Matrix
resins are commonly classified in terms of their process-
ing temperature range or their service temperature looking
for environmental stability. DSC and rheology are among
the most important tools of processability testing [1–6].
These combined tests characterize the degree of curing
and its effect on the melting temperature and glass tem-
perature transition. The function of processability testing
is to find the optimum processing “window“, which is
a combination of processing time, temperature, pressure
for consolidation, resin flow, and chemical curing of the
composite laminate. These processability studies should
always be accompanied by appropriate chemical analysis
[1, 7–15].
0022-2461
C
2006 Springer Science + Business Media, Inc.
DOI: 10.1007/s10853-006-6082-1
4349