Chemically Modified Natural Rubber Blends

Furthermore, the C=C bonds in the natural rubber structure might induce poor thermal and oxidative resistance in the natural rubber blends. Thus, Thawornwisit and coworkersproposed the preparation of hydrogenated natural rubber, which is one of the chemical modifications available to improve the oxidation and thermal resistance of diene-based natural rubber before blending with poly(methyl methacrylate-co-styrene). The poly(methyl methacrylate-co-styrene) was resistant to the outdoor environment and had excellent optical properties with a high refractive index, but it was extremely brittle and had low impact strength. Hydrogenated natural rubber could, however, be used as an impact modifier, as well as to improve its thermal and oxidative resistance for these acrylic plastics. 

The mechanical and viscoelastic behaviours of natural rubber based blends and interpenetrating polymer networks (IPNs) are fimctions of their structures or morphologies. These properties of blended materials are generally not constant and depend on the chemical nature and type of the polymer blends, and also enviromnental faetors involved with any measurements. Preparations of natural rubber blends and IPNs are well known as effeetive modifieation methods used to improve the original meehanieal and viscoelastie properties of one or both of the eomponents, or to obtain new natural rubber blended materials that exhibit widely variable properties. The most common consideration for their mechanical properties include strength, duetility, hardness, impact resistance and fracture toughness, each of which can be deformed by tension, compression, shear, flexure, torsion and impaet methods, or a eombination of two or more methods. Moreover, the viseoelastieity theory is a way to predict the behaviours of deformation of natural rubber blends and IPNs. The time and... 

The major cost in ESBR manufacture is the purchase of the monomers. The monomer price is dependent on the crude oil price, but can fluctuate quite widely due to other reasons. ESBR is a raw material (a raw rubber) which is sold to the rubber goods producers. There it is mixed with reinforcing fillers, oil and vulcanising chemicals to produce rubber compounds. The mbber compound is then shaped and vulcanised under heat and pressure to produce the finished rubber article. Often, the ESBR is blended with other types of raw rubber, such as natural rubber or polybutadiene, to modify the properties of the finished article. 

NR is a renewable natural resource, whereas synthetic polymers are mostly manufactured from petroleum. The use of NR is an environmentally advantageous alternative to synthetic polymers. In order to improve or modify the properties of NR and also extend its use, two major methods have been developed. One is by chemical reaction to modify the molecular structure of NR. Another approach is to blend it with other polymers, with the use of both plastics and rubbers being reported. Only chemical modifications will be discussed in this chapter. 

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