Polymer science be considered polymer science in the modern sense. In the 1840s, Friedrich Ludersdorf and Nathaniel Hayward independently discovered that adding sulfur to raw natural rubber (polyisoprene) helped prevent the material from becoming sticky. In 1844 Charles Goodyear received a U.S. patent for vulcanizing natural rubber with sulfur and heat. Thomas Hancock had received a patent for the same process in the UK the year before. This process strengthened natural rubber and prevented it from melting with heat without losing flexibility. This made practical products such as waterproofed articles possible. It also facilitated practical manufacture of such rubberized materials. Vulcanized rubber
Rubber elasticity Joule published the first careful measurements of the temperature increase accompanying extension, confirming the theoretical predictions of Lord Kelvin. It was not until 1838 that the American inventor Charles Goodyear found that its properties could be immensely improved by adding a few percent sulphur. The short sulfur chains produced chemical cross-links. Before it is cross-linked, the liquid natural rubber consists of very long linear chains, containing thousands of isoprene backbone units, connected head-to-tail. Every chain follows a random path through the liquid and is in contact with thousands of other nearby chains. When heated, a cross-linker molecule (such as sulfur