To preserve the environment, we have designed an advanced process of vulcanized rubber recycling, which generates a secondary raw material suitable for the production of new articles, thus contributing to environmental sustainability. Our advanced solutions allow the recycling of end-of-life tires, seals, etc., by reducing production costs and obtaining a secondary raw material from selected waste, compatible with the initial formulation.
Devulcanization is the process which – by breaking the crosslinks between chains – a vulcanized rubber is turned into a new plastomeric material, thus making it re-processable and recyclable.
Our thermo-mechanical process is a 100% green approach that does not involve the use of devulcanizing additives or solvents. For example, for a sulfur-based vulcanized rubber, thermomechanical devulcanization is made possible by the different chemical-physical characteristics of the CC, CS and SS bonds. Specifically, a marked difference is highlighted in terms of bond spring constant (kcc≈100>kcs>kss≈3) and a different bond energy (respectively 370, 310 and 270 kJ/mol).
| Material | Rubber |
|---|---|
|
Polymer |
Vulcanized rubber |
|
Origin |
Post-consume or post-industrial |
|
Final use |
Same or different use |
| EXTRUDER SETUP | |
|---|---|
|
L/D |
64-72 |
|
Degassing points |
1 |
| FORMULATION | |
|---|---|
|
Ground rubber |
100% |
Through our devulcanization process, we can recycle a wide range of materials, including:
ELTs
(End-of-Life Tires) including car, truck and Off-road vehicles tires
ACM
Polyacrilic Rubber
BR
Butadiene Rubber
EPDM
Ethylene Propylene Diene Monomer
FKM
Fluoroelastomers
IIR
Butyl Rubber
IR
Isoprenic Rubber
NR
Natural Rubber
Q
Silicone Rubber
SBR
Styrene Butadiene Rubber
From chemical and rheological analysis carried out on devulcanized materials, it has been found that the devulcanization yield can reach 50-90%, according to the formulation and the process parameters.
Devulcanized material can be reused in the same original application, from 15 to 50% mixed with the virgin rubber while maintaining the desired mechanical properties. For different final applications, it is possible to use devulcanized rubber in a blend with percentages higher than 50%.
| C-TSE (mm) | 20 | 30 | 40 | 50 | 58 | 70 | 80 | 92 | 112 | 133 |
| Capacità produttiva* (kg/h) | 5 | 20 | 50 | 80 | 100 | 150 | 250 | 400 | 550 | 800 |
| 10 | 30 | 80 | 100 | 150 | 250 | 400 | 500 | 700 | 1000 |
* the above data strongly depend on the rubber type and/or morphology
To produce devulcanized rubber with very high-quality standards, we have designed and patented a two-stage devulcanization process: Evorec Rubber Plus.
In the first phase, the co-rotating twin-screw extruder devulcanizes the rubber, which feeds the second extruder through direct connection. The second phase –
given by the combination of a single screw extruder and a screen-changer –
allows the sudden cooling of the devulcanized rubber and its filtration.
The sudden cooling of the devulcanized rubber allows to contain the temperature of the extruded strip by minimizing the degradation of the rubber. The effects are observable both in terms of mechanical properties of the recycled material and in terms of reduced emissions of odorous gases.
The rubber filtration operation – made possible thanks to the high thrust capacity of the single-screw extruder – allows to filter the devulcanized rubber before its extrusion, by increasing once again the mechanical properties and, more generally, the quality of the material recycled.