A dynamic mechanical thermal analysis (DMTA) was performed on allylester polymers and composites filled with alumina. We determined the glass transition temperatures and the values of the storage moduli in both the glassy and rubbery states in each system and compared the mechanical-thermal behavior of pristine allylester polymers with that of composites filled with alumina. To supplement the result of DMTA, we also carried out viscometry, gel permeation chromatography, and differential scanning calorimetry. The molecular structures had an influence on the viscosity, the glass transition temperature, and the storage modulus. Allylester composite filled with 20 phr alumina showed peculiar mechanical-thermal behavior.