Characterisation of Deproteinised Natural Rubber Latex Foam for Enhanced Acoustic and Vibration Isolation

Abstract

Natural acoustic foams used in recording studios, auditoriums, cinemas, etc., are largely of petrochemical origin and cause environmental and health problems. The current research explores the application of natural rubber (NR) latex foam as a substitute material. Three types of NR latex foams low ammonia (LATZ), deproteinized (DPNR), and epoxidized (ENR)were developed and characterized for their acoustic and mechanical performance. Sound performance was tested in an impedance tube to ISO 10534-2, for sound absorption coefficient (SAC), noise reduction coefficient (NRC), and sound transmission loss (STL). Results indicate that STL is a rising function of foam density, while SAC in the low-frequency range is a function of density but in high frequencies of morphological structure. Among the foams, high-density DPNR latex foam possessed the highest his paper investigates nonlinear dynamic behaviour in a bolted beam.  Force-Controlled Technique (FCT), NRC, surpassing ENR and LATZ foams and commercial memory foam. Further mechanical evaluation of the DPNR foam revealed increased resilience, as evidenced by a maximum ball rebound and minimum hysteresis loss compared to polyurethane (PU) and memory (PM) foams. DPNR latex foam was also successfully manufactured in the configuration of seat cushions through the Dunlop batch process. Pressure-relief performance, as measured by a CONFORMatTM sensor system and mannequin, showed that DPNR cushions were lower in peak pressure than PU foam and were comparable with PM foam. Vibration transmissibility tests, as conducted in accordance with ASTM D3580-95, showed that the lowest attenuation frequency for DPNR latex foam resulted from low stiffness and high resilience. These findings identify DPNR latex foam as a highly potential, eco-friendly acoustic insulation and ergonomic cushioning material particularly for electric vehicle (EV) seat applications.