Regeneration of ground tire rubber (GTR) by pulsed discharge plasma in a fluidized-bed system

The disposal of scrap rubber poses an enormous environmental issue, and the regeneration of waste tire rubber is considered one of the most attractive solutions [1]. Regeneration process mainly involves the destruction of three-dimensional network of vulcanized rubber [2]. Processes involving plasma rubber regeneration are currently being investigated as an alternative to the traditional regeneration technologies. In this work, an atmospheric pressure plasma fluidization system is developed and employed for the regeneration of ground tire rubber (GTR). Compared with plasma fixed-bed system, plasma fluidized-bed system can achieve better gas-powder contact, and obtain a uniform and efficient powder treatment [3]. Through evaluating the effect of electrode diameter, air velocity and electrical parameters on discharge power to optimize the plasma generation method. The surface properties of plasma-treated GTR particles at different plasma treatment time are analyzed by means of water contact angle, sedimentation test, X-ray photoelectron spectroscopy, attenuated total reflection-Fourier transform infrared spectroscopy, scanning electron microscopy and atomic force microscopy. Additionally, the GTR regeneration performance is evaluated through cross-linking density and mechanical property tests. It is demonstrated that after plasma treatment for 30 min, the cross-linking density decreases from 3.4 x 10
^-4
mol/cm
³
to 1.9 x 10
⁴
mol/cm
³
, and the tensile strength increases from 6.6 MPa to 9.2 MPa, an increase of 39.4%, indicating that the internal network structure of GTR is partially destroyed, and the scrap rubber is regenerated to a certain extent. This may be related to the formation of hydrophilic functional groups on GTR surface, which improves the weak compatibility between GTR interfaces. Meanwhile, the increase in surface roughness enhances the contact area between particles, facilitating rubber tableting [4]. This plasma fluidization system may provide a new avenue for scrap rubber regeneration.