Filler-surface modifier coupling agent

Competitive adsorption of components of filler surface modifier systems, stabilisers and lubricants, etc., is an inevitable event that occurs in the vast majority of filled polymer formulations. Such phenomena can lead to inferior product performance in terms of reduced coupling agent efficiency and poor stabilisation. Therefore an understanding of such events is very beneficial if performance is to be optimised. 

In addition to the raw material cost, one also has to take into account compounding costs, the cost of any coupling agent or surface modifier that is not already present on the filler and the cost of additional stabilisers that might be re-... 

Spectroscopic techniques are extremely useful for the characterization of filler surfaces treated with surfactants or coupling agents in order to modify interactions in composites. Such an analysis makes possible the study of the chemical composition of the interlayer, the determination of surface coverage and possible coupling of the filler and the polymer. This is especially important in the case of reactive coupling, since, for example, the application of organofunctional silanes may lead to a complicated polysiloxane interlayer of chemically and physically bonded molecules [65]. The description of the principles of the techniques can be found elsewhere [15,66-68], only their application possibilities are discussed here. 

H NMR transverse magnetisation relaxation experiments have been used to characterise the interactions between NR, isoprene rubber, BR, EPDM and polyethylacrylate rubbers with hydrophilic silica and silicas modified with coupling agents [124-129]. These studies showed that the physical interactions and the structures of the physical networks in rubbers filled with carbon black and rubbers filled with silicas are very similar. In both cases the principal mechanism behind the formation of the bound rubber is physical adsorption of rubber molecules onto the filler surface. 

---