Vibration damping and acoustic properties of syntactic foam incorporating waste tyre-derived rubber particles

This paper investigates the impact of incorporating non-functionalised, micro-sized rubber particles derived from end-of-life tyres on the vibration damping and acoustic properties of syntactic foam. To elucidate the effects of rubber particles on the vibration properties of rubberised syntactic foam, a laser Doppler vibrometer was used to evaluate the vibration damping response and natural resonance frequencies. Integrating rubber particles lowered the syntactic foam's natural resonance frequency due to reduced stiffness and increased density. In relation to vibration damping performance, the optimal rubber size was 250–425 μm. The vibration damping performance increased with rubber content due to the viscoelastic properties of the elastomeric fillers. The mode II response revealed a 75% increase in vibration damping ratio upon the integration of 23 vol% of rubber particles. The sound absorption coefficient, measured using an impedance tube, increased with the rubber content. Additionally, the coincidence frequency in SYN(5)-EF(23) was 40% higher than that of the baseline foam. This research expands our understanding of the interplay between the constituents, the vibration damping and acoustic properties of the rubberised foam. These findings offer a pathway to optimising vibration control and acoustic performance using upcycled waste tyre-derived products.