Polymer modifications diene-based

Representative diene-based polymers include natural rubber (NR), polyisoprene (PIP), PBD, styrene—butadiene rubber (SBR), and acrylonitrile-butadiene rubber (NBR), which together compose a key class of polymers widely used in the rubber industry. These unsaturated polyolefins are ideal polymers for chemical modifications owing to the availability of parent materials with a diverse range of molecular weights and suitable catalytic transformations of the double bonds in the polymer chain. The chemical modifications of diene-based polymers can be catalytic or noncatalytic. The C=C bonds of diene-based polymers can be transformed to saturated C—C and C—H bonds (hydrogenation), carbonyls (hydrofbrmylation and hydrocarboxylation), epoxides (epoxidation), C—Si bonds (hydrosilylation), C—Ar bonds (hydroarylation), C—B bonds (hydroboration), and C—halogen bonds (hydrohalogenation). ... 

Hydroformylation involves the reaction of C=C bonds with syngas (i.e., a mixture of carbon monoxide and hydrogen) and produces aldehyde functional groups. Hydroformylation of diene-based polymers is mostly performed by means of providing sites for further derivations. The most commonly explored secondary modification of aldehyde functional groups is hydrogenation to give primary alcohol functionality however, aldehyde may also be converted to nitrile, acetate, or amine functionalities. " ... 

The epoxidation of diene-based polymers is advantageous because it provides active sites along the polymer chains for further modification. Furthermore, introducing an epoxide functional group to unsaturated polymers can help improve abrasion resistance, adhesive strength, and heat stability. Epox-idized polymers can be prepared by polymerizing epoxidized monomers however, this method typically results in many side reactions. Numerous reports have focused on the epoxidation of diene-based polymers with... 

The chemistry involved with crosslinking of diene-based systems is largely speculative. Since crosslinked systems, by their nature, are completely insoluble, all analytical procedures which require solutions of the polymers are unusable. IR spectroscopic techniques are of limited value because the spectrum of polystyrene blocks out most frequencies other methods are difficult in the solid state. Most work reported in this area is based on measuring the fraction of insolubles and some indication of how tightly crosslinked the insoluble component has become (by a swelling index test). The presence of occluded polystyrene in the gel fraction of typical rubber-modified plastics further complicates the issue, although Karam and Tien have attempted to allow for this problem through a modification of the Flory-Rehner equation. 

Addition polymers are of great importance and are obtained from olefin monomers by sequential covalent addition, as discussed in Chapter 1. It was observed in Chapter 2 that many vegetable oils may be heated with other vinyl monomers to modify their surface coating properties. The modification of triglyceride oils by the copolymerisation of drying and semi-drying oils with vinyl monomers such as styrene, a-methylstyrene or cyclopenta-diene, is one of the oldest methods used in vegetable oil-based chemistry. The products obtained by this technique possess improved film properties and styrene has been found to be the most important monomer for this purpose. 

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