Lignocellulosic fibre mediated rubber composites: An overview

The rising concern towards the reduction in the use of petroleum-based, non-renewable resources and the need for more versatile polymer-based composite materials have led to increasing interests on natural polymer composites filled with natural organic fillers, i.e. coming from renewable and biodegradable sources. This paper reviews wood flour and other lignocellulosic fibres filled rubber composites, including cellulosic rubber composites, cellulosic thermoplastic elastomers, nanocellulose based rubber nanocomposites, with the aims at providing the most state of the art information for directing further scientific research, possible commercialization and design of cellulosic rubber composites. It has been found that 1) the surface properties of natural cellulose, hence the compatibility and interface of the natural cellulose and matrix rubber/plastics, are crucial for the successful development of the composites, such, physical and chemical modification and additives have been widely attempted to improve the incompatibility and poor interfacial adhesion between the filler and matrix; 2) the curing characteristics, mechanical properties, thermal stability and morphologies of the composites are complex but closely related to not only the interfacial properties, but also the compositions (e.g. the concentration of cellulosic materials) and other processing parameters; 3) the nature of hydrophilic cellulosic and hydrophobic matrix rubber and/or plastics requires an accurate introduction of coupling agent, one end of its structure shall be compatible to hydrophilic and the other to hydrophobic. The reviews on the main paths and results of study on the advanced nanocellulose reinforced rubber nanocomposites and sandwiches indicate much potentials and needs for further in-depth studies.