Degradação térmica do polietileno tereftalato (PET): obtenção de parâmetros cinéticos a partir da equação de Arrhenius.

Abstract

Polymer degradation is a change in the tensile strength and properties of a polymer or polymer based product under the influence of one or more environmental factors such as heat, light or chemicals. Within such a process, for example, biodegradation is desirable, deliberately by lowering the molecular weight of a polymer for recycling, or decomposing it into the environment. The present work presents a simple experimentation sequence, using a heat source as the main experimental activity. In addition, it uses the thermal degradation process of Polyethylene Terephthalate (PET) as a subsidy to obtain kinetic parameters. Based on numerical calculations and mainly the Arrhenius equation, it was possible to determine the pre exponential factors (A) and the activation energies (Ea) involved in this process. As a means of comparison, the same tests were performed with pure PET and after that, with the addition of two catalysts specific to the MCM-41, Al-MCM-41 and La-MCM-41 mesostructured catalysts, through comparisons in the (Al3 +) and (La3 +) cations belong to the same valence layer, the aluminum catalyst favored the process by decreasing the activation energy due to the presence of aluminum (trivalent ion, Al 3 + ) by isomorphic substitution to silicon (tetravalent ion, Si4) in the MCM-41 structure to generate Bronsted acid sites. However the catalyst with Lanthanum was not satisfactory to the process, since it increases the activation energy involved, since the presence of available f orbitals makes the rare earth with properties / chemical behavior very characteristic to the lanthanide elements.