Bob Gore joined the company in 1963 upon completion of a Ph.D. in chemical engineering at the University of Minnesota. In 1969, he was researching a process for stretching extruded PTFE into pipe thread tape when he discovered that the polymer could be "expanded." The discovery followed a series of unsuccessful experiments in which he was attempting to stretch rods of PTFE by about 10%. As it turned out, the right conditions for stretching PTFE were counterintuitive. Instead of slowly stretching the heated material, he applied a sudden, accelerating yank that unexpectedly caused it to stretch about 800%. This resulted in the transformation of the solid PTFE into a microporous structure that was about 70% air. The company initially referred to this new material as "fibrillated PTFE". One year later, it was given the name of "Gore-Tex expanded PTFE". Today, expanded PTFE (ePTFE) accounts for the vast majority of the company's products.