Charles goodyear discovered the rubber vulcanization in 1837 Polymer strands Fig 18.(a)when stretched the individual poly- isoprene strands in natural rubberlip past Original for Stretched with little tendency to snap back to original form one another and the rubberstays stretched. Polymerstrands (when vulcanized rubber is stretched, the Polymer strands sulfur cross-links hold the strands together, allowing the rubber to return to its original shape (b)Original form with disulfide Stretched with great tendency to cross-links snap back because of cross-linksCharles Goodyear discovered the rubber vulcanization in 1837. (a) Original form Stretched with little tendency to snap back to original form Stretched with great tendency to snap back because of cross-links (b) Original form with disulfide cross-links Fig18.6 (a) when stretched, the individual poly-isoprene strands in natural rubber slip past one another and the rubber stays stretched. (b) when vulcanized rubber is stretched, the sulfur cross-links hold the strands together, allowing the rubber to return to its original shape Polymer strands Polymer strands