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chemistry open book:formation of natural and synthetic rubber

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Introduction

Formation of natural and synthetic rubber Natural rubber is a polymer of the monomer isoprene, formed by addition polymerisation, one double bond in isoprene open to form a bond with the next isoprene monomer, so they create a large chain. Isoprene polymers form cis isomers, this means that all the groups orientate in the same direction, producing crystalline alignment, which makes the polymer strong. Synthetic rubber is similar to natural rubber, in that polymerisation is used to produce long chains. Initially when double bonded alkenes (dienes) were used the polymers were found to contain both cis and trans isomers (shown in the diagram). Now we use butadiene, which forms poly (cis-1, 3-butadiene), which contains cis bonds.# The best synthetic rubbers are produces from copolymers, which have been made by join together a diene and an additional alkene. The polymer is made using emulsion polymerisation, the diene and alkene are polymerised in water. A detergent is added so the polymer spreads out to form a colloidal. Another man made process to produce rubber is to polymerise an alkene, 2-methylpropene, which only contains one double bond. ...read more.

Middle

Oils and resins allow more carbon black to be integrated into the rubber, which helps extend the lifetime of the rubber, without deteriorating. They also make rubber more flexible which stops it becoming brittle; this prevents the rubber cracking in cold temperatures. Curing agents, such as sulphur are added to rubber in the vulcanising process, which produces more rigid tyres. # This stops tyres melting at higher temperatures. Anti-ageing chemicals are needed to prevent the tyre from wearing out in the tough conditions it's put in. Recycling used tyres to produce commercial products "The European union landfill directive (1999) required that member countries should have banned the burial of whole tyres in landfill sites by 2003 and should stop burying shredded tyres by 2006" Figure 14 In the EU alone, 2 million tonnes of tyres are scrapped every year, but with the legislation banning the burial of tyres new ways to dispose of tyres have to be thought up. Leeds University has researched into a new process to recycle old tyres, called pyrolysis. Pyrolysis breaks down tyres using heat, but with out oxygen. The tyres do not burn; instead they break down to oil, gas, solid carbon and the steel casing, all of which can be easily separated and recycled. ...read more.

Conclusion

Figure 9 Fig 6 from article 1, advanced subsidiary GCE, chemistry salters, skills for chemistry: open book exam, OCR Figure 10 Fig 29, pg 111, Chemical ideas, Second Edition, Salters Advanced Chemistry, by George Burton, john Holman, john Lazonby, Gwen Pilling and David Waddington Figure 11 Fig 7 from article 1, advanced subsidiary GCE, chemistry salters, skills for chemistry: open book exam, OCR Figure 12 Table 1, from article 1, advanced subsidiary GCE, chemistry salters, skills for chemistry: open book exam, OCR Figure 13 Fig 35, pg 116 Chemical ideas, Second Edition, Salters Advanced Chemistry, by George Burton, john Holman, john Lazonby, Gwen Pilling and David Waddington Figure 14 box 4, article 2 advanced subsidiary GCE, Chemistry Salters, skills for chemistry: open book exam, OCR Figure 15 box 2, article, advanced subsidiary GCE, Chemistry Salters, skills for chemistry: open book exam, OCR Figure 16 box 2, article, advanced subsidiary GCE, Chemistry Salters, skills for chemistry: open book exam, OCR Figure 17 box 2, article, advanced subsidiary GCE, Chemistry Salters, skills for chemistry: open book exam, OCR 18. http://www.itdg.org/docs, for information about recycling rubber ?? ?? ?? ?? ...read more.

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