This article analyzes the effect of the type of surface modification (using silane coupling agents and dicarboxylic acids) on titanium dioxide particles used as fillers in polylactic acid composites, which were exposed to a photodegradative process. The thermomechanical properties of the composites were analyzed; it was found that the silane coupling agent with imidazole allowed the composites to have Young’s modulus values 60% lower than the composite without filler. On the other hand, the crystallization rate was 30% higher for composites with azelaic acid attached to TiO2 particles than for composites without filler at a cooling rate of 5 °C min-1.