Styrene Butadiene Styrene Block Copolymer
SBS is the largest-volume (accounting for more than 70%), lowest-cost, and most widely used variety among SBCs. It is a triblock copolymer with styrene and butadiene as monomers. It has the properties of both plastic and rubber and is known as the “third generation of synthetic rubber”. Similar to styrene-butadiene rubber, SBS can come into contact with water, weak acids, alkalis, etc. It has excellent tensile strength, high surface friction coefficient, good low-temperature performance, excellent electrical properties, and good processing performance, making it the most consumed thermoplastic elastomer.
SBS Advantages
A. It can be processed and molded by thermoplastic processing equipment, such as extrusion, injection, blow molding, etc., and the molding speed is faster than the traditional vulcanized rubber process;
B. No vulcanization is required, and the vulcanization process in the general thermosetting rubber processing process can be omitted, so the equipment investment is small, the production energy consumption is low, the process is simple, the processing cycle is short, the production efficiency is high, and the processing cost is low;
C. The corners and leftovers can be recycled many times, saving resources and benefiting environmental protection.
SBS is mainly used in four major fields: rubber products, resin modifiers, adhesives and asphalt modifiers. In terms of rubber products, SBS molded products are mainly used in the shoemaking (sole) industry, and extruded products are mainly used for hoses and tapes; as a resin modifier, a small amount of SBS is blended with polypropylene (PP), polyethylene (PE), and polystyrene (PS) to significantly improve the low-temperature performance and impact strength of the product; SBS as an adhesive has the characteristics of high solid content, fast drying, and low temperature resistance; SBS as a modifier for building asphalt and road asphalt can significantly improve the weather resistance and load resistance of asphalt.
Recycling of Styrene-Butadiene-Styrene Block Copolymer (SBS)
Physical recycling methods
Physical recycling mainly separates the components of waste plastics through physical means such as mechanical crushing, screening, magnetic separation and gravity separation. This method is energy-saving and widely used, and is specifically used to recycle PET and HDPE. However, physical recycling is limited when recycling other types of plastics, such as PVC and PP, which will degrade, and LDPE tends to damage the machine. In addition, the physical recycling process does not remove inks, dyes or additives, so the produced recycled plastic is impure and has a low market price.
Chemical recycling methods
Chemical recycling is a series of physical and chemical processes to extract monomers or polymers from waste plastics, aiming to overcome the process inefficiency of physical recycling. Chemical recycling methods include pyrolysis and depolymerization. Pyrolysis performs well in converting mixed plastics into fuels, while depolymerization has dominated in PET recycling. However, these methods still have shortcomings in the types of plastics that can be recycled and the recycling yield.
The latest technology – solvent dissolution recycling
Solvent dissolution is a unique physical recycling method that uses a solvent mixture to separate contaminants such as dyes, adhesives or metals from plastics, leaving pure polymers for reuse. This method can purify polymers from a mixture without breaking them down into monomers. The solvent dissolution process includes two main pathways: dissolution layering and selective dissolution. Dissolution layering is suitable for complex structures such as multi-layer plastics and solar panels, while selective dissolution is suitable for a wider range of waste plastics such as textile waste.
