Determination Of The Gel Point Of A Resin Via Dma Testing Essay
The DMA is used to determine the modulus values of the resin to associated temperatures and frequencies. The state of viscosity of the resin is also monitored through the evaluation of tan delta values.
Gel-point of a resin implies that resin matrix has transformed into an elastic gel state and can no longer flow. The viscosity shows a sudden rise to extremely high values. The time at which this state is detected marks the onset of gelation of the resin. Gel-point essentially is at the crossover of storage modulus and loss modulus since the value of storage modulus increases due to transition from fluid to a rather solid-like elastic state. 
Use of DMA as a simple check on post cured state of composite laminates
DMA can be used to determine various mechanical properties of a composite laminate in its post-cured state. One such essential parameter is Glass Transition Temperature, abbreviated as Tg. Glass transition temperature is defined as a range of temperature (rather than a set point) where the material undergoes transformation from being a stiff and ‘glass’ like state to soft and ‘rubber’ state. This is possible due to movement of the molecules of the material inside the polymer matrix on account of gained energy from an external source.
The primary importance of the glass transition temperature is that it signifies a range of temperature in which the material transformed from…