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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Curing (chemistry) | 2/2 | https://en.wikipedia.org/wiki/Curing_(chemistry) | reference | science, encyclopedia | 2026-05-05T10:47:03.298418+00:00 | kb-cron |
=== Thermal analysis === If the reactions occurring during crosslinking are exothermic, the crosslinking rate can be related to the heat released during the process. The higher the number of bonds created, the higher is the heat released in the reaction. At the end of the reaction, no more heat will be released. To measure the heat flow differential scanning calorimetry can be used. Assuming that each bond formed during the crosslinking releases the same amount of energy, the degree of curing,
α
{\displaystyle \alpha }
, can be defined as follows:
α
=
Q
Q
T
=
∫
0
s
Q
˙
d
t
∫
0
s
f
Q
˙
d
t
{\displaystyle \alpha ={\frac {Q}{Q_{T}}}={\frac {\int _{0}^{s}{\dot {Q}}\,dt}{\int _{0}^{s_{f}}{\dot {Q}}\,dt}}}
where
Q
{\displaystyle Q}
is the heat released up to a certain time
s
{\displaystyle s}
,
Q
˙
{\displaystyle {\dot {Q}}}
is the instantaneous rate of heat and
Q
T
{\displaystyle Q_{T}}
is the total amount of heat released in
s
f
{\displaystyle s_{f}}
, when the reaction finishes. Also in this case the degree of curing goes from zero (no bonds created) to one (no more reactions occur) with a slope that changes in time and has its maximum about at half of the reaction.
=== Dielectrometric analysis === Conventional dielectrometry is carried out typically in a parallel plate configuration of the dielectric sensor (capacitance probe) and has the capability of monitoring the resin cure throughout the entire cycle, from the liquid to the rubber to the solid state. It is capable of monitoring phase separation in complex resin blends curing also within a fibrous perform. The same attributes belong to the more recent development of the dielectric technique, namely microdielectrometry. Several versions of dielectric sensors are available commercially. The most suitable format for use in cure monitoring applications are the flat interdigital capacitive structures bearing a sensing grid on their surface. Depending on their design (specifically those on durable substrates) they have some reusability, while flexible substrate sensors can be used also in the bulk of the resin systems as embedded sensors.
=== Spectroscopic analysis === The curing process can be monitored by measuring changes in various parameters:
the concentration of specific reactive resin species using spectroscopic methods such as FTIR & Raman; the refractive index or fluorescence of the resin (optical property); the internal resin strain (mechanical property) with the use of Fiber Bragg grating (FBG) sensors.
=== Ultrasonic analysis === Ultrasonic cure monitoring methods are based on the relationships between changes in the characteristics of propagating ultrasound and the real-time mechanical properties of a component, by measuring:
ultrasonic time of flight, both in through-transmission and pulse-echo modes; natural frequency using impact excitation and laser-induced surface acoustic wave velocity measurement.
== See also == Vulcanization Cross-link
== References ==
Osswald, Tim A.; Menges, Georg (2003). Materials science of polymers for engineers. Hanser Verlag. pp. 334–335. ISBN 978-1-56990-348-3. Glöckner, Patrick (2009). Radiation Curing. Vincentz Network. pp. 11–16. ISBN 978-3-86630-907-4. I.Partridge and G.Maistros, 'Dielectric Cure Monitoring for Process Control', Chapter 17, Vol. 5, Encyclopaedia of Composite Materials (2001), Elsevier Science, London, page 413 P.Ciriscioli and G.Springer, 'Smart Autoclave cure in Composites', (1991), Technomic Publishing, Lancaster, PA.