Uberlayer abrasion
Overall, the most important factors in the commercial viability of SBR making it material of choice over other rubbers are: Better abrasion resistance and resistance to degradation (under heat)Īlso, scorch problems are less likely to occur with SBR than with NR.However, there are properties which makes it superior over natural rubber. Other disadvantages include:īut the addition of resins and reinforcing fillers adequately improve these properties. While most of the properties of SBR are comparable with NR, but in some respects like heat build-up, tack and gum tensile strength make it inferior to natural rubber. *It enables the synthesis of polymers with a very narrow molecular weight distribution and less chain branching. Outstanding resistance to abrasion and fatigue.S-SBR rarely has more than 2% non-rubber materials in its finished form while e-SBR may have an emulsifier (soap) content of up to 5% and nonrubber materials sometimes in excess of 10%. Solution SBR has a narrower molecular weight distribution, higher molecular weight, and higher cis-1,4-polybutadiene content than emulsion polymerization SBR. S-SBR grades have improved flexibility, performance, superior mechanical properties like tensile strength, low rolling resistance etc. Solution SBR is produced by termination-free*, anionic solution polymerization of styrene and butadiene with alkyl lithium initiator (e.g., butyllithium) in a hydrocarbon solvent, usually hexane or cyclohexane. High styrene resins have good low-temperature properties but stiffen.Hot polymers are difficult to process with low green strength.Low resistance to oil, other hydrocarbon fluids and ozone.Low resilience and low tensile strength.
Green strength becomes low with increasing oil extension.It also exhibits superior mechanical properties such as tensile strength compared to grades produced by the hot emulsion polymerization route On the other hand, Cold SBR has a better abrasion resistance and, consequently, provides better tread wear and dynamic properties.SBR grades produced using this process have exception processing characteristics such as low mill shrinkage, good dimensional stability, and good extrusion characteristics The hot emulsion SBR process, which was developed first, leads to a more branched polymer than the cold emulsion process.It can be produced by free-radical emulsion polymerization of styrene and butadiene either at 50 to 60☌ (hot emulsion SBR) or at about 5☌ (cold emulsion SBR). Emulsion SBR (e-SBR) - Hot SBR or Cold SBR.Today, there are two major types of SBR with different properties based on their manufacturing process: