The overall properties of fibre composites are affected by the properties of the matrix immediately adjacent to the fibres, which can be different from the average or bulk properties. The thermal image of a cross-section through a composite (above) shows the presence of fibres (the bright areas) by means of their higher thermal conductivity than the subtstrate. Micro TA is an ideal method of investigating the spatial variations in glass transition as illustrated below.

The results show how the glass transition changes dramatically from being very high (above the range used for the measurements) then progressively lower further away from the fibre. In this case it is believed to arise a consequence of the high thermal conductivity of the fibre, which ensures a high temperature immediately around the fibres during the cure cycle.