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
Union Sulphur Company original patents thus expired in 1908. Competitors such as the Freeport Sulphur Company quickly emerged and began to use the Frasch Process to extract sulfur from other nearby salt dome sites. The Union Sulphur Company tried to stop the Freeport Sulphur Company by suing on the basis of later patents that improved upon the original patents. The Delaware District Court largely sided with the Union Sulphur Co. The Third Circuit Court of Appeals, however, reversed the district court, concluding that the new patents were not really new inventions, but merely extensions of the original expired patents. Union Sulphur appealed to