Thermomechanical Properties of Nylon 6,6/Polyester Hybrid Tire Cord: Effect of Twist Level and Core Ratio

Design and production of hybrid tire cords is a simple and cost-effective way to improve the physical and thermal properties of the tire. It also affects the fuel consumption of the vehicle.

In this study, to achieve new reinforcing materials with better performance using conventional fibers, a hybrid tire cord has been manufactured by twisting nylon 6.6 and polyester yarns together. The effects of twist level and core ratio were studied on the thermomechanical properties of the hybrid cord. The produced cords have different twist levels of 300, 350 and 400 tpm and core ratios of 1.00, 1.03, and 1.05. The mechanical properties of these cords, including strength and creep, have been studied. The heat shrinkage and shrinkage force were also measured and compared with reference samples, nylon and polyester yarns and cords. The dynamic mechanical thermal analysis (DMTA) was used to examine the shrinkage force and creep of the tire cords.

The results show that the yield strain and shrinkage of all hybrid cords were lower than those of the nylon cord and more than those of the polyester cord. The increase in the twist level leads to a decrease in the load at specific elongation (LASE), and also an increase in the creep due to the helix angle between the cord axis and filament axis. In addition, the LASE, work to rupture and creep increase, as the core ratio increases. Furthermore, a rise in twist level and core ratio leads to an increase in shrinkage and shrinkage force. The hybrid tire cord with a core ratio of 1.05 due to its dimensional stability and good mechanical properties can be used to design high-performance tires.