Sulfur vulcanization in the processing and compounding of rubber by Hancock and his colleagues led to a more reliable process. Around 1900, disulfiram was introduced as a vulcanizing agent, and became widely used. In 1905 George Oenslager discovered that a derivative of aniline called thiocarbanilide accelerated the reaction of sulfur with rubber, leading to shorter cure times and reducing energy consumption. This breakthrough was almost as fundamental to the rubber industry as Goodyear's sulfur cure. Accelerators made the cure process faster, improved the reliability of the process and enabled vulcanization to be applied to synthetic polymers. One year after his discovery, Oenslager
Rubber toughening materials where crazing and yielding are comparable, a bimodal distribution of particle size may be useful for toughening. At fixed rubber concentrations, one can find that an optimal particle size is a function of the entanglement density of the polymer matrix. The neat polymer entanglement densities of PS, SAN, and PMMA are 0.056, 0.093, and 0.127 respectively. As entanglement density increases, the optimum particle size decreases linearly, ranging between 0.1 and 3 micrometers. The effect of particle size on toughening is dependent on the type of test performed. This can be explained because for different test conditions, the failure mechanism