Capillary non-Newtonian seepage model of unvulcanized rubber expressed by the four-parameter rheological flow

Micro-bubbles and pores in a tire, generated by the seepage process of rubber into steel cord, seriously degrade the safety of the tire in use. However, unclear seepage behavior of unvulcanized rubber while flowing into the interstice of steel cord makes it difficult to eliminate defects. Here, we studied the seepage behavior of unvulcanized rubber in a single capillary. When the four-parameter rheological flow was compared to the common shear rheological model, it was best suited to represent the rheological behavior of unvulcanized rubber because of its lowest variance. On this basis, the single capillary seepage equation of unvulcanized rubber was developed to interpret the relationship between the flow rate, process length, pressure, and pore diameter in a single capillary tube. And it was validated by the finite element analysis method with the four-parameter rheological equation as the material parameter; the accuracy of the single capillary seepage equation reached 99.95%. It lays a foundation for further exploring the seepage model under complex conditions such as variable aperture and multiple channels.