The term "vulcanised" refers to a manufacturing process
- which is chemical in nature - that transforms rubber into polymer.
The manufacturing method for achieving vulcanization varies; the
most common method uses sulfur - which is atomic number 16. You
may ask what is the point of transforming rubber into a polymer?,
the advantage is the durability of polymer - the higher the chain
length of the polymer, the greater it's impact resistance. When
it comes to shoes, most shoes now have a rubber sole; a vulcanised
rubber sole results in a sole which is less likely to warp and degrade
over time. It's common to find vulcanised sole's on shoes intended
for manual work or for extreme outdoor pursuits such as mountaineering
or skateboarding. The footwear brand well known for it's vulcanised
rubber sole is vans; a company with a heavy focus upon "skate"
shoes, or footwear designed for skateboarding and urban sports.