The Effect of Manganese Palmitate as Pro-Oxidant Additive on Mechanical Properties of Polypropylene

Polypropylene (PP) is one of the most widely used polymer materials, such as in textile, automotive spare part, furniture, household appliances, and packaging. However, PP is very difficult to degrade naturally. When the product from PP is not reused and discharged into the environment, this plastic can cause problems to the environment. One of the solution to improve degradability of PP is by adding pro-oxidant additives. The addition of pro-oxidant additives can make polypropylene to easily oxidize and degrade into shorter chains by producing carbonyl groups. The pro-oxidant additive used in this research is manganese palmitate. The additive was synthesized by reacting palmitic acid with sodium hydroxide and followed by reaction with manganese chloride tetrahydrate. The purpose of this research was to study the effect of manganese palmitate as a pro-oxidant additive to the structure and mechanical properties of PP before and after thermal treatment. The thermal treatment was carried out by providing heating in PP at various temperatures (25, 60, and 90°C) for 2, 4, 6, 8, and 10 days. The structure and mechanical properties of PP was characterized by functional group analysis (FTIR) and mechanical properties (Tensile tester). FTIR spectra of PP film after thermal treatment at temperature 60 and 90°C showed the presence of carbonyl group in 1700-1720 cm⁻¹ region. After thermal treatment at 90°C, PP film could not be analyzed by mechanical properties because it was damaged and destroyed. The peak intensity of the carbonyl group increased with the increasing temperature of heating. PP films with the addition of manganese palmitate both before and after thermal treatment have a lower tensile strength and elongation compared to the pure PP, but their modulus young are higher, so that the films of PP with addition of pro-oxidant became more fragile and rigid. In addition, the PP film with heating treatment at 90°C cannot be analysed due to it was damaged and destroyed.