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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.

Nanoparticles are generally defined as particles having one or more dimensions of sizes ranging from 1 to 100 nm. Nanoparticles can be classified into organic, inorganic and carbon-based materials. In comparison with conventional micro-size particles, nanoparticles show enhanced properties, such as high reactivity, strength, surface area, sensitivity and stability due to their nanosize. Various preparation methods, viz. physical, chemical and mechanical, have been employed to synthesize different nanoparticles. This chapter presents an overview on nanoparticles and their types, properties, synthesis methods and application in bioconversion of biomass into biofuels.

Ground tire rubber (GTR) has been used as a sustainable low-cost modifier in various composites. However, due to the hydrophobic nature of GTR, it is in compatible with most matrices and results in deterioration in both mechanical and physical properties of composites. This necessitates pre-modification of the powdered rubber to improve the interfacial bonding at the rubber-matric interface. The most common GTR modification research relies on surface etching via use of various techniques. The current review aims to give a detailed overview of the surface etching chemical modification methods for GTR for incorporation into various matrices such as concrete, bitumen and polymers. The review will serve as a guide for engineers, chemists and manufactures with interest of including GTR in any type of composite for achieving compatibility with the main matrix. The surface chemical etching treatment methods such as acid etching, hydroxylation, oxidation, and radiation methods are discussed in this work. The characterization methods to confirm the functional groups on the modified GTR and the effect of the treatment on the resultant GTR composites are also highlighted. Finally, this review highlights the advantages and limitations of the chemical surface etching processes for GTR.

The usage of polymer composites has increased dramatically with the years, especially composites with recycled waste materials since they aid in reducing the environmental pollution. The current study focuses on the use of both waste reclaimed rubber (RR) and wood flour (WF) to make sustainable polymer composites. The curing, thermal, mechanical and morphological properties of the composites were studied. Results showed that the cure rate index and elastic torque of the samples increased with the amount of WF. The mechanical properties of RR–WF composites decreased with increasing wood flour content and tensile strength dropped from 3.33 MPa to 1.35 MPa due to poor interfacial adhesion between WF and RR matrix. The glass transition temperature of styrene–butadiene rubber fraction in composites shifted from ∼15 °C to 10 °C with the addition of WF showing incompatibility between the two phases. The scanning electron microscopy results confirmed incompatibility behavior within the composites as shown by pull-out characteristics of WF from the RR matrix at high content. The results showed that the composite with 10 phr of WF has superior thermal stability, water absorption, and mechanical properties compared to other composites.

Copyright: RSC. Due to copyright restrictions, the attached PDF file contains the preprint version of the published item. For access to the published version, please consult the publisher's website: http://dx.doi.org/10.1039/9781788013482

The most common strategies for the recycling of waste rubbers have been the conversion of rubbers into thermoplastic elastomers and use in composite foams. The advantages of waste rubber composite foams are that they are lightweight, low cost and provide an ecological and economic solution for the disposal of waste rubbers. Rubber foams possess interesting properties such as thermal and acoustic insulation, as well as impact damping. This has led to their use in thermal insulation, energy absorption and non-structural applications. This book chapter aims to document the findings relating to the use of waste rubber, for example waste ground tyre rubber (GTR), waste latex gloves and waste ethylene propylene diene monomer (EPDM) in composite foams. The chapter will describe the common processing techniques used to manufacture such composite foams and studies dealing with the preparation and characterization of waste rubber composite foams and their properties have also been enumerated. Finally, the applications of the rubber foams in different industrial sectors are also discussed.