[en] Trifunctional epoxy resin triglycidyl paraaminophenol (TGPAP)/CaCO₃ nanocomposites were prepared using the melt blending method. The effects of nano-CaCO₃ content 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-CaCO₃ content was increased, the T_g of the TGPAP/CaCO₃ nanocomposites 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-CaCO₃ particles and the epoxy matrix, as well as the high crosslinking density in the TGPAP/CaCO₃ nanocomposites. The CTE of the nanocomposites in the rubbery region was significantly decreased as the nano-CaCO₃ content was increased