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Foaming of rubber is a well-known technique and foamed rubber products have found application in various industries including cushioning, heat insulation and sound absorption. In the current study, the foaming of reclaimed tyre rubber (RTR), as an alternative to virgin rubber, is explored. The effect of varying the amounts of waste ethylene vinyl acetate (filler), sodium bicarbonate (blowing agent) and dicumyl peroxide (co-curative) on the RTR properties was studied. Composites formulations were obtained by use of the simplex-lattice mixture design and the samples were prepared by following two foaming techniques namely, prepressing and free foaming. Hardness of free foamed samples was found to be lower than that of prepressed samples, owing to effective foaming and the formation of multiple microcells in the former. An increase in blowing agent content resulted in decreased density and thermal stability of the foamed composites. Dicumyl peroxide caused an increase in density but had no effect on thermal stability. The incorporation of a filler in formulations effected an increase in the gel content and thermal stability of the foams. Free foamed samples exhibited higher shrinkage with an increase in both waste ethylene vinyl acetate and sodium bicarbonate. However, dicumyl peroxide significantly increased the shrinkage of prepressed samples, whereas sodium bicarbonate decreased the gel content and thermal stability of both free foamed and prepressed samples. It is demonstrated in the current work that both foaming processes are applicable for RTR and the choice of the processing method is dependent on the desired properties of the composites.

This report documents the facile synthesis of molecular brushes, via a grafting onto approach, with potential application as coating binders. Firstly, alternating copolymers of n-butyl vinyl ether (n-BVE) and maleic anhydride (MAh), i.e. n-BVEMAh, were synthesized via conventional radical polymerization. The anhydride reactive handle was subsequently utilised to access molecular brushes, via a grafting onto method, by imidizing the MAh repeat units with amine end-functional poly(ethylene glycol) oligomers, with 12 repeating units (PEG12-NH2). The product n-BVEMI-PEG12 brushes were viscous liquids at room temperature, hence we termed them liquid molecular brushes (LMBs). The LMBs displayed Newtonian flow behaviour at shear rates below 1000 s−1. We evaluated the applicability of this molecular brush system as coating binder, by grafting varying fractions of linoleamide (Lin) side chains, which has oxidative crosslinking ability, along with the PEG12 onto n-BVEMAh, to access n-BVEMI-PEG12/Lin. The n-BVEMI-PEG12/Lin binders underwent oxidative crosslinking at 50 °C in the presence of a drier. The challenges associated with the current binder system are highlighted.