Charles Goodyear and his family suffered through years of failure and poverty before he succeeded in making rubber a viable commericial product.  Despite attributes of natural rubber as a water-proof material, potentially useful for a number of products, heat caused it to liquefy and extremes of cold caused it to become brittle.  Goodyear processed rubber with sulfa and lead, discovering that the addition of these substances alleviated manufacturing problems associated with natural rubber.  Vulanize rubber was the invention made by Goodyear that allowed it to become a commericially successful material.