Previous experiments have shown that microwave curing of epoxies reduces th
e curing time and could lead to improvements in the mechanical properties o
f the cured epoxies, Precise temperature control is important as inadequate
control may lead to thermal "run-away", resulting in localized material da
mage. Consequently, the main objective of the present work is to use temper
ature for controlling the intensity of microwave radiation during the adhes
ive curing process. Using microwave energy delivered through a slotted wave
guide at a frequency of 2.45 GHz, and with the power varied between 300 and
600 W, three engineering thermoplastics or adherends were joined by curing
two types of "two-pack" epoxy adhesives. Subsequently, the bond strengths
of the microwave cured samples were compared to those of the specimens cure
d in ambient conditions by subjecting the joined samples to shear loading.
The results obtained indicate that the samples cured with microwave under a
temperature feedback control protocol achieved higher bond strengths after
curing for only a fraction of the time required for ambient curing, It can
therefore be inferred that, with an adequate temperature control strategy,
increased efficiency of curing, higher quality of adhesive joint, and impr
oved bond strength can be achieved when joining thermoplastics. (C) 2000 El
sevier Science Ltd. All rights reserved.