There are disclosed a regenerated rubber, a method and apparatus for obtaining regenerated rubbers from vulcanized crumb rubber, such as rubber from scrap. The apparatus is a thermokinetic mixer having the particularity to have an air tight stationary chamber with inner non-uniform surface. The method comprises the steps of raising the speed of the rotor shaft in order to increase a temperature of a mixture made of vulcanized crumb rubber and a lubricant, such as oil, until a devulcanizing temperature is reached; and reducing the temperature of the mixture to a lower temperature during a second period of time. The method of the invention is environmentally friendly or “green”, since the regeneration method does not use chemicals, includes a shorter period of treatment at higher temperature avoiding the risks of rubber cracking and spontaneous combustion, and further allowing mass-production of regenerated rubber with lower energy consumption.