Influence of Composition of uPVC on Mechanical Properties of Window Profiles Exposed to Weathering

The durability of unplasticized poly(vinyl chloride) (uPVC) components used in the building industry is a function of the interaction of several factors. Types and quantities of additives incorporated to the PVC resin and defining the formulation of the PVC compound used in the production of these components are among the most important such factors. White uPVC window profiles with different formulations have been exposed to five years of natural weathering under Brazilian climatic conditions. Results of Charpy impact tests were used to assess the influence of three factors on the durability of the profiles: additivation levels of titanium dioxide, nature of the impact modifier, and nature of the thermal stabilizer. Statistical analysis of the results made it possible to rank these factors according to their influence in component durability. The influence of composition of uPVC on mechanical properties of window profiles is demonstrated by means of the study of the modulus of elasticity. Results presented in this paper indicated the need for several additional experiments in order to check changes in molecular mass and color. Comparison of all these data with results from profiles subjected to accelerated weathering led to straightforward criteria for prediction of the potential behavior of uPVC, to be described in a future paper.