Physical phenomena related to free volumes in rubbers and blends

A J MARZOCCA; W SALGUEIRO; A SOMOZA

?Advances in Elastomers II: Composites and Nanocomposites

Springer, Germany

Lugar: Berlin; Año: 2013; p. 399 - 426

In the present chapter, different aspects related to free volumes and thephysical phenomena involving free volumes in rubbers and blends are discussed.Experimental results were obtained using conventional experimental techniques(e.g. dynamic mechanical tests, differential scanning calorymetry and swelling)and principally a non-conventional one (positron annihilation lifetime spectroscopy?PALS). PALS has demonstrated a high capability to give direct informationon free volumes. Due to its significant role in the study of nanoscopic effects inmolecular systems (among them polymers), the physical grounds of the techniqueare explained. It is also illustrated how PALS detects free nanohole volumes andgives information on their changes as a consequence of different reactions inducedin polymers. Based on the latest experience of the authors, some examples ofPALS studies on NR and SBR rubbers and NR/SBR blends are presented. Theresults obtained are discussed using a modern scientific approach to the study ofphysicals processes in these elastomers; i.e. the analysis of the experimentalinformation is given into the frame of well recognized theoretical models.