Abstract
Short aramid fibres were incorporated into butadiene-acrylonitrile copolymer rubber (NBR). An adhesion system (hydrated silica, resorcinol and hexamethylene tetramine) (HRH) was used to strengthen the bond between the rubber and the fibres. The rheological, tensile, ultrasonic properties and the hardness were determined by standard test methods. The properties of the composites improved as the fibre content increased up to 30 phr by weight.
Longitudinal and transverse ultrasonic velocities were used to calculate the elastic parameters of the composites. Ultrasonic results were then used to assess the bonding between the fibres and the rubber matrix as well as the sound absorptive potential of the composites.
Scanning electron microscopy (SEM) demonstrated that the fibre distribution in the rubber was satisfactory.
Regression analysis was used to clarify the correlation between the longitudinal tensile strength and ageing time. The strain energy increased with fibre content while the fatigue life decreased.