Thermal behaviour of TiO2-encapsulating polymers

Comparing the thermal properties of TiO₂ encapsulating polystyrene and poly(methyl methacrylate) with those of TiO₂ dispersion polymers it was found that the encapsulating polymers have two thermal relaxation regions. The activation energy of those thermal relaxation regions was determined using the Wunderlich method and it was found that the values are similar to the activation energy for the dynamic dispersion. It is suggested that the low-temperature thermal relaxation is caused by the local change of conformation of molecular chains, while the high-temperature thermal relaxation is similar to that of the normal glass transition temperature including the interaction with TiO₂. In addition, the thermal behaviour near the degradation point in different atmospheres indicates that the encapsulating polymer has a specific structure for adsorbing a large amount of oxygen.