Thermal stability of trifunctional epoxy resins modified with nanosized calcium carbonate

Trifunctional epoxy resin triglycidyl paraaminophenol (TGPAP)/CaCO₃nanocomposites were prepared using the melt blending method. The effects of nano-CaCO₃content on the thermal behaviors, such as cure behavior, glass transition temperature (T_g), thermal stability, and the coefficient of thermal extension (CTE), were investigated by several techniques. Differential scanning calorimetry (DSC) results indicated that the cure reaction of the TGPAP epoxy resin was accelerated with the addition of nano-CaCO₃. When the nano-CaCO₃content was increased, the T_gof the TGPAP/CaCO₃nanocomposites did not obviously change, whereas the crosslinking density was linearly increased. The nanocomposites showed a higher thermal stability than that of the neat epoxy resin. This result could be attributed to the increased surface contact area between the nano-CaCO₃particles and the epoxy matrix, as well as the high crosslinking density in the TGPAP/CaCO₃nanocomposites. The CTE of the nanocomposites in the rubbery region was significantly decreased as the nano-CaCO₃content was increased.