Rheological Properties and UV Photo-oxidation of Montmorillonite-filled random Propylene-Ethylene Copolymers

RIECHERT, VERÓNICA M.; FERROFINO, ANÍBAL G.; QUINZANI, LIDIA M.; FAILLA, MARCELO D.

POLYMER BULLETIN

SPRINGER

Lugar: Berlin; Año: 2022 vol. 80 p. 3981 - 4004

0170-0839

Random propylene-ethylene copolymers (RPC) are a type of polyolefin in increasing demand, mainly for packaging, due to its high impact resistance, large durability as well as high transparency and flexibility. The present study aims to investigate the morphological and rheological properties, as well as the photo-oxidation by UV-irradiation, of five different RPCs and their nanocomposites. Organophilic montmorillonite is used as the filler and maleic anhydride grafted RPCs as compatibilizers. The aging was performed by exposing strips of the materials to UVA radiation for a maximum period of ninety six hours, and the degradation was analyzed following the evolution of carbonyl and hydroperoxide groups by FTIR and crystallinity by DSC. All nanocomposites display intercalated-exfoliated structures being the largest particle disaggregation presented by the polymer with the largest molecular weight. The rheological behavior supports these observations. Neither the chemical composition of the polymers nor the presence of nano-clay/compatibilizer affects the photo-degradation mechanism of the copolymers although the composite structure promotes the matrix photo-degradation. A parabolic relation was found between the carbonyl and hydroxyl indexes of all stabilized and extracted materials, with or without clay. An increase in crystallinity was observed in all systems with a maximum determined in the case of the extracted systems.