Nano and Nanostructured Fillers and Their Synergistic Behavior In Rubber Composites Such As Tires

Nano and Nanostructured fillers and their synergistic behavior in rubber composites such as Tires

 

Maurizio Galimberti^a,b, Michele Coombs^,b, Valeria Cipolletti^a,b, Luca Giannini^,b, Theonis Riccò^c ,

Lucia Conzatti^d, Marco Mauro^e, Gaetano Guerra^e

^aPolitecnico di Milano, Via Mancinelli 7, Milano (I)  ^bPirelli Tyre, Viale Sarca 222, Milano (I) 

^cUniversità degli Studi di Brescia, Via Valotti 9, Brescia (I)  ^dCNR-ISMAC UOS Genova, Via De Marini 6, Genova (I)  ^eUniversità di Salerno, Via Ponte Don Melillo, 84084 Fisciano (SA)(I)

New characters are on the scene of fillers for elastomeric materials, the so-called nano-fillers. A basic feature characterizes their identity: they are made by primary particles having at least one dimension of one or few nanometers, that can be individually dispersed in a polymer matrix. Conversely, fillers such as carbon black (CB) and silica are nanostructured, being formed by aggregates of nano-sized primary particles that can not be separated via thermomechanical mixing. An impressive research activity has been developed on rubber composites based on nano-fillers, both in the academic and industrial worlds, with the aim to take advantage of their uniqueness. Layered silicates have been prevailingly investigated [1, 2] but many data are also reported on carbon nanotubes (CNTs) [3], whereas a preliminary knowledge is available for graphene [4].

In this work, clay, carbon nanotubes and graphene were studied vis a vis as nanofillers for rubber composites. They were used as the only fillers or in the presence of a suitable amount of either CB or silica. The filler networking phenomenon was investigated through tensile and dynamic-mechanical tests and DC electrical conductivity measurements were also performed.  Morphology, dispersion and filler networks were visualized through transmission electron microscopy (TEM). The chance of crosslinking the elastomer chains allowed to compare the properties of the composite material in the uncured and cured states. Compounds were prepared with formulations typical for application such as the one for a tyre compound.

The behaviour of nano and nanostructured fillers is comparatively discussed  and a particular focus is payed on their ability to develop cooperative and synergistic effects.

[1] Chen, B.; Evans, J. R. G.; Greenwell, H. C.; Boulet, P.; Coveney, P. V.; Bowden, A. A.; Whiting, A.; “A critical appraisal of polymer-clay nanocomposites”, Chem. Soc. Rev. , 2008, 37, 568-594.

[2] “Rubber Clay Nanocomposites – Science, Technology, Applications” M. Galimberti Editor, Wiley and Sons, Book in preparation

[3] Bokobza L. “Multiwall carbon nanotube elastomeric composites: a review”  Polymer 2007, 48, 4907-20.

[4] J.R. Potts, D. R. Dreyer, C. W. Bielawski, R. S. Ruoff “Graphene-based polymer nanocomposites” Polymer 2011, 52, 5-25