An extract on #eskiehirspor
Optimizing rolling resistance in the elastomer material is a key challenge for reducing fuel consumption in the transportation sector. It is estimated that passenger vehicles consume approximately 5~15% of its fuel to overcome rolling resistance, while the estimate is understood to be higher for heavy trucks. However, there is a trade-off between rolling resistance and wet traction and grip: while low rolling resistance can be achieved by reducing the viscoelastic properties of the rubber compound (low tangent ()), it comes at the cost of wet traction and grip, which requires hysteresis and energy dissipation (high tangent ()). A low tangent () value at 60 C is used as an indicator of low rolling resistance, while a high tangent () value at 0 C is used as an indicator of high wet traction. Designing an elastomer material that can achieve both high wet traction and low rolling resistance is key in achieving safety and fuel efficiency in the transportation sector.
The most common elastomer material used today is a styrene-butadiene copolymer. It combines butadiene, which is a highly rubbery polymer (Tg = -100 C) that has low hysteresis and thus offers good rolling resistance, with styrene, which is a highly glass polymer (Tg = 100 C) that has high hysteresis and thus offers good wet grip properties in addition to wear resistance. Therefore, the ratio the two polymers in the styrene-butadiene copolymer is considered key in determining the glass transition temperature of the material, which is correlated to its grip and resistance properties.
Materials science research efforts are underway to improve such properties of elastomers. For instance, this involves modifying the microstructure of the copolymer (for instance, using solution styrene butadiene rubber (S-SBR) to control the addition of vinyl butadiene units) as well as the macrostructure of the polymer (such as the width of molecular weight distribution (MWD)). Current investigation also involves looking at the functionalization of the elastomer through the addition of filler materials such as silica and carbon black, as well as testing other nano-fillers such as nanocellulose crystals, carbon nanotubes, and graphene.
Trialkoxymercaptoalkyl-silanes are a class of silane bonding agents that offer advantages in reduced rolling resistance and emission of volatile substances.
Tread lugs often feature slitssipesthat improve the flexibility of the lug to deform as it traverses the footprint area. This reduces shear stress in the lug and reduces heat build up. Testing of identical siped and unsiped tires showed measurable improvements in snow traction and ice braking performance, however diminishing and extending braking distances on wet and dry pavement by a few feet on siped tires. Off-road tire enthusiasts have been siping tires for years for greater traction, as many manufacturers now offer already siped off-road-tires.