Structural properties of vegetable oil thermosets: Effect of crosslinkers, modifiers and oxidative aging

ANBINDER, SEBASTIÁN; MEIORIN, CINTIA; MACCHI, CARLOS; MOSIEWICKI, MIRNA A.; ARANGUREN, MIRTA I.; SOMOZA, ALBERTO

EUROPEAN POLYMER JOURNAL

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2020 vol. 124

0014-3057

The present work is focused on the study of the formulation effect of cationically polymerizedvegetable oil thermoset on their aging behavior. Toward this aim, tung oil-based biopolymerswere prepared using different comonomers or adding a modifier. Specifically, synthetic andnatural comonomers (styrene, divinylbenzene and a methyl ester of tung oil) and a modifier(acrylated epoxidized soybean oil) were used to prepare different crosslinked samples with afixed weight ratio of tung oil/comonomer (or modifier) = 70/30. The chemical aging sufferedby the fatty acid segments of the matrix, which is known as autoxidation of unsaturated fatty acids in oils and alkyd resins, was followed by Fourier transformed infrared spectroscopy, dynamic-mechanical analysis, positron annihilation lifetime spectroscopy and thermogravimetric analysis. As a result, values of the glass transition temperature, the storage moduli, tan  and the free nanohole volumes were obtained. To study the influence of the aging process on the network structures at molecular level, the evolutions of the glass transition temperatures, storage moduli, tan  and free nanohole volumes were followed for one year at two different aging conditions: room temperature and 50 °C.The chemical changes leading to nanostructural variations in all the studied samples are discussed in terms of the formed networks and the degradative processes during aging.