Factors affecting the adsorption of stabilisers on to carbon black (flow micro-calorimetry studies) - Part III - Surface activity study using acid/base model probes

The first and second part of this series of papers investigated the interac tion between carbon black and stabilisers (phenolic antioxidants and HALS, respectively) and showed that the mechanism was dependent on both the chemi cal nature of the carbon black surface and the molecular structure of stabi lisers. In this third part, the interactions between model compounds, of va rying acidity, and the same four carbon blacks, are investigated using flow micro-calorimetry (FMC) and Fourier transform Infrared spectroscopy (FTIR) . As with the first and second parts, differences in adsorption behaviour b etween the four types of carbon black were evident and were principally rel ated to the chemical nature of the surfaces and the adsorbates. In this stu dy further insight in to the nature of the interactions between the carbon black surface functional groups and the acidic and basic probes has been ac quired. The main forms of interaction are hydrogen bonding and Lewis and Br onsted acid/base interactions, formation of proton transfer complexes was a lso considered possible in cases of strong adsorption. The adsorption behav iour of acid and basic aromatic probes, together with octadecanol and stear ic acid, was also found to be dependant on the carbon black surface topogra phy. Flat graphene layers containing minimal heteroatoms favoured adsorptio n of the latter species as flat adsorption and/or structural ordering was p ermissable. (C) 2001 Kluwer Academic Publishers.