Foamability study, fabrication and characterisation of deproteinised natural rubber latex foam

Abstract

This study examines the feasibility of Pureprena® latex foam with the aim of offering a safer alternative to traditional natural rubber (NR) latex foam, particularly for applications requiring lower protein allergenicity. The research investigates the effects of deproteinisation on foamability, manufacturing processes, and the properties of Pureprena® latex foam. The foamability and stability of the latex foam were evaluated using two different instruments: the FoamScan® analyser, which measures foamability of the latex and foam decay, and the Kenwood® mixer simulates foam generation under production-like conditions. Key stages of latex foam production include compounding, foaming, gelling, moulding, and vulcanisation. Potassium oleate was employed as a foaming agent, and Pureprena® latex foam demonstrated excellent foam stability, with less than 15% volume decay. The physical properties of Pureprena® and LATZ latex foams were compared across high- and low-density formulations. In high-density foams (0.20 g/cm³), both materials exhibited similar characteristics, including approximately 11% volume shrinkage and compression set values of 5.8% (LATZ) and 5.5% (Pureprena®). Low-density formulations (0.10 g/cm³) showed reduced shrinkage, indicating enhanced dimensional stability. Both foams met elongation requirements, with values of 390% for LATZ and 370% for Pureprena®. Additionally, the extractable rubber protein content in Pureprena® latex foam was remarkably low (< 50 µg/g), indicating its suitability for applications where hypoallergenic properties are important.