Evaluation of chemical degradation of commercial polypropylene

One of the polymers most commonly used in the automotive industry is polypropylene. Despite its importance and the number of experiments that have been carried out, its chemical degradation in different environments is still a subject of debate. Degradation experiments were carried out to evaluate resistance behavior with polypropylene samples exposed to basic acids or organic mixtures. Polypropylene was subjected to a degradation process for 0 and 1000 h. Also two atmospheric conditions were analyzed: polypropylene immersed in a liquid and polypropylene exposed to saturated atmosphere. The environments were solutions of water and NaCl, H2SO4, HNO3, HCl and AcH, NaOH and NaClO, and finally solvent as diesel engine and unleaded gasoline. A reduction of resistance properties and high plasticity was observed in strongly solvent environment as unleaded gasoline. On the other hand, a different tendency was seen in the rest of environments, but in general the resistance properties were similar with respect to original polypropylene. On the other hand, thermal studies also were performed. Microstructural changes of polypropylene were analyzed by dynamic mechanical thermal analyzer (DMTA).