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Upscaling of a Batch De-Vulcanization Process for Ground Car Tire Rubber to a
Continuous Process in a Twin Screw Extruder
#MMPMID28773843
Saiwari S
; van Hoek JW
; Dierkes WK
; Reuvekamp LEAM
; Heideman G
; Blume A
; Noordermeer JWM
Materials (Basel)
2016[Aug]; 9
(9
): ? PMID28773843
show ga
As a means to decrease the amount of waste tires and to re-use tire rubber for
new tires, devulcanization of ground passenger car tires is a promising process.
Being an established process for NR and EPDM, earlier work has shown that for
ground passenger car tire rubber with a relatively high amount of SBR, a
devulcanization process can be formulated, as well. This was proven for a
laboratory-scale batch process in an internal mixer, using diphenyl disulfide as
the devulcanization aid and powder-sized material. In this paper, the
devulcanization process for passenger car tire rubber is upscaled from 15 g per
batch and transformed into a continuous process in a co-rotating twin screw
extruder with a capacity of 2 kg/h. As SBR is rather sensitive to devulcanization
process conditions, such as thermal and mechanical energy input, the screw design
was based on a low shear concept. A granulate with particle sizes from 1-3.5 mm
was chosen for purity, as well as economic reasons. The devulcanization process
conditions were fine-tuned in terms of: devulcanization conditions
(time/temperature profile, concentration of devulcanization aid), extruder
parameters (screw configuration, screw speed, fill factor) and ancillary
equipment (pre-treatment, extrudate handling). The influence of these parameters
on the devulcanization efficiency and the quality of the final product will be
discussed. The ratio of random to crosslink scission as determined by a Horikx
plot was taken for the evaluation of the process and material. A best practice
for continuous devulcanization will be given.
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