Polypropylene degradation in NaOH environments

This paper involves the effect of 2, 5 and 7% sodium hydroxide solutions on polypropylene at room temperature, 35 and 40 °C by measuring the weight changes of the samples. The following experiments were performed on polypropylene specimens: Case 1, effect of 2, 5 and 7% sodium hydroxide solution on polypropylene at room temperature; Case 2, effect of 2, 5 and 7% sodium hydroxide solution on polypropylene at 35 °C; Case 3, effect of 2, 5 and 7% sodium hydroxide solution on polypropylene at 40 °C. Each sample was exposed to the sodium hydroxide solutions for a period of 30 days. The appearance of the immersion medium was also noted as discoloration could indicate the extraction of soluble components; however, there was no visible change in the sodium hydroxide solutions and there was no discoloration of the polypropylene samples. The results showed that the polypropylene samples lost mass steadily. The severity of attack increased as temperature rose and as concentration of sodium hydroxide decreases.