Rubber toughening and damage competition theory. In material selection it is important to look at the interaction between the matrix and the secondary phase. For example, crosslinking within the rubber phase will promote high strength fibril formation that will toughen the rubber, preventing particle fracture. Carboxyl-terminated butadiene-acrylotnitrile (CTBN) is often used to toughen epoxies, but using CTBN alone increases the toughness at the cost of stiffness and heat resistance. Amine-terminated butadiene acrylonitrile (ATBN) is also used. Using ultra-fine full-vulcanized powdered rubber (UFPR) researchers have been able to improve all three, toughness, stiffness, and heat resistance simultaneously, resetting the stage for rubber toughening
Sulfur 14th century the Latin ' was restored, for '; and by the 15th century the full Latin spelling was restored, for "sulfur, sulphur". The parallel "f~ph" spellings continued in Britain until the 19th century, when the word was standardized as "sulphur". "Sulfur" was the form chosen in the United States, whereas Canada uses both. The IUPAC adopted the spelling "sulfur" in 1990, as did the Nomenclature Committee of the Royal Society of Chemistry in 1992, restoring the spelling "sulfur" to Britain. Oxford Dictionaries note that "in chemistry and other technical uses ... the "-f-" spelling is now the standard form