CHANGES IN THE MECHANICAL, MICRO-, AND NANO-STRUCTURAL PROPERTIES OF REINFORCED VULCANIZED NATURAL RUBBER COMPOUNDS: THEIR DEPENDENCE ON THE SiO2/CB RATIO

MARZOCCA, ANGEL J.; RODRÍGUEZ GARRAZA, ANA L.; ANBINDER, SEBASTIÁN; MACCHI, CARLOS; SOMOZA, ALBERTO

RUBBER CHEMISRTY AND TECHNOLOGY

Rubber Division, American Chemical Society

Año: 2021

0035-9475

A systematic study on the influence of fillers on the structural properties at micro- andnanoscale of vulcanized compounds based on a natural rubber matrix reinforced withsilica and/or carbon black is presented. Several compounds with different SiO 2 /CBratios (1.5/1, 2.25/1 and 3/1) and total filler contents (55, 60 and 65 phr) were preparedand vulcanized at 150 °C. The experimental techniques used were rheometric, swellingand dynamic mechanical tests, and positron lifetime spectroscopy. From thesetechniques, cure reaction parameters, the fraction at the maximum degree of swelling,storage modulus, loss tangent and fractional free volume were measured. Using arecent model based on a hydrodynamic description and the percolation of aggregatesin a rubber matrix it was found that, regardless of the fillers combinations, the dynamicstorage modulus is well represented as a function of the filler volume fraction. Besides,beyond a critical SiO 2 /CB ratio (2.25/1) in the formulations of the compounds, theloss tangent does not depend on the SiO 2 /CB ratio. The results obtained show adirect correlation among mechanical properties, swelling and fractional free volume,and the type and amount of fillers in the reinforced compoun