Dynamical mechanical thermo analysis of high performance composites - Influences and problems

A sensitive method to characterize the thermomechanical behavior of fiber r einforced composites is the dynamic mechanical thermo analysis (DMTA) metho d. A Round-Robin-Test with five different institutes was conducted to deter mine the role of the fiber orientation, processing conditions, test apparat us, mode of lending as well as the fiber and matrix materials on the determ ination of the glass transition temperature (T-g). The results show that th e DMTA is a suitable method to analyze T-g of long fiber composites; howeve r some major problems have to be taken into consideration. A direct compari son between the results obtained from different DMTA-systems is not possibl e since the real temperatures in the specimens deviated from the temperatur es displayed by the DMTA measuring system. Therefore, no clear and common e valuation method for the glass transition temperature can be established. T he significant influences on the T-g is proven by the performed statistical analysis.