I would like to ask about the relationship between the microstructure of rubber used in tires and its properties
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I would like to ask those who are familiar with rubber: what is the general relationship between the microstructure of the rubber used in tires (the structure of polymer chains) and its main macroscopic properties (such as low rolling resistance, wet grip, wear resistance, etc.)? Thank you!
The structure of rubber seems quite complex; I remember it being a network-like structure. Carbon particles are added to prevent slippage. Sulfidation is used to form a network structure. To give it a certain strength. I’m not quite sure about the rest.
Rolling resistance and wet skid resistance mainly depend on the flexibility of the molecular chains, the number of chain ends, and side groups, etc. Rubbers with good molecular chain flexibility, fewer chain ends, and weaker steric effects from side groups allow for ample movement of the molecular chains; as a result, they exhibit low hysteresis loss and low dynamic heat generation. This leads to low rolling resistance, but poor resistance to wet skidging. Wear resistance is related to intermolecular forces, side groups, etc. Rubbers with regular molecular chains, few side groups, and some that can self-reinforce have a low coefficient of friction and good wear resistance ； However, strong intermolecular forces can also improve its wear resistance.
Thank you, the explanation is very professional! I have another question: there are grades of styrene-butadiene rubber with a high vinyl content, which are said to be used primarily in aircraft tires. Is the increase in vinyl content intended to add side groups, thereby increasing rolling resistance?