Compressive Stress-Strain and Rebound Resilience Properties of Deproteinized Natural Rubber Latex Foam

Abstract

Deproteinized natural rubber (DPNR) latex is a modified version of natural rubber (NR) latex that is hypoallergenic and odorless when used in products. However, due to the lack of studies in this field, there are relatively few DPNR latex foam products to date. Our laboratory has developed a novel manufacturing technique that involves a heat-enzymatic reaction followed by a concentration procedure to generate DPNR latex directly from freshly tapped latex and to manufacture a novel DPNR latex foam using the Dunlop batch foaming procedure. To investigate the mechanical properties of the foam, ball-rebound resilience studies and compression tests were conducted on DPNR latex, commercial grade polyurethane (PU) and polyurethane memory (PM) foams as a comparison. Compressive stress-strain study revealed that the hysteresis loss ratio of DPNR latex foam, PU foam, and PM foam is 0.19, 0.66, and 0.86, respectively. DPNR latex foam exhibits the lowest hysteresis loss ratio due to its elastic behavior thus able to store a high amount of energy when under compressed. On the other hand, the rebound resilience of DPNR latex foam, PU foam, and PM foam is 74%, 29%, and 9%, respectively, indicating that DPNR latex foam has the highest rebound resilience. The resilience property is correlated with the elasticity, dimensional stability and durability of foam materials. Thus, DPNR latex foam is suitable for heavy-duty cushion applications including seats for transportation industry.