Effect of thermo-oxidation on loss of plasticizers, on crystalline features and on properties in a metallocene isotactic polypropylene

Abstract

Incorporation of a low content of several plasticizers into a metallocene isotactic polypropylene (iPP) has been performed in order to learn about their stability and performance by the action of a thermo-oxidative degradation treatment at 95 °C for different times. Comparison with the behavior exhibited by the material with di(2-ethylhexyl) phthalate (DEHP) is established for a feasible replacement of its use for contributing to environmental and human health preservation. Dependence of these aggressive degrading conditions on plasticizer loss is analyzed as well as elucidation of degradation influence on the iPP crystalline characteristics. The results show that chemical changes associated with this degradation process hinder formation of the orthorhombic γ crystalline lattice and postpone the overall crystallization capability. Accordingly, the final features in the film surface and the mechanical response are significantly affected by degradation time. The TOTM plasticizer can be considered an excellent candidate for DEHP substitution.