Evolution of the crosslink structure in the elastomers NR and SBR

An experimental positron annihilation lifetime spectroscopy (PALS), differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS) study of the effect of the advance of the crosslinking reaction on the free volume in a copolymer of styrene–butadiene and natural rubbers was carried out. The crosslink density developed in SBR specimens with different sulfur contents and cure temperatures was studied. SAXS technique was applied to study the process of crosslinking in NR as a function of the cure temperature. Finally, a study of different SBR/NR blends is presented using PALS and DSC.