Maillard reaction in Natural Rubber (NR) latex was investigated by treating fresh NR latex with glutaraldehyde (C5H8O2) in amounts of 0, 50, 100, and 200 mmol/kg of latex. Protein cross-linking in fresh NR latex and solid NR was confirmed by using sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and attenuated total reflection infrared (ATR-IR) spectroscopy, respectively. It was found that degree of protein cross-linking in NR increased with increasing C5H8O2concentration. Physical properties of untreated and treated NR substances in terms of gel content, initial Wallace plasticity (P0), plasticity retention index (PRI), Mooney viscosity, and tensile strength were carefully explored. Results clearly showed that the Maillard cross-linking of proteins had remarkable effect on bulk NR properties, that is, solvent resistance, hardness, resistance to oxidation, rheological behavior, and resistance to stretching out.

For natural rubber (NR) gloves, residual latex processing chemicals are the important substances that cause adverse reactions to users who are sensitive to them. Many attempts have therefore been made to reduce or eliminate these leachable chemicals from the gloves such as natural compound addition and polymer coating. The current study proposed a novel alternative method to reduce chemical allergens from NR gloves by protein crosslinking through the Maillard reaction that is possible to adapt to the existing glove production. Commercial NR gloves were initially treated with various concentrations of glutaraldehyde, a crosslinking agent, ranging from 0.00% to 1.00%w/w prior to being tested for cytotoxicity, contact angle, water absorption, and mechanical properties. Artificial sweat and culture medium with serum (complete medium) were used as vehicles for in vitro cytotoxicity tests. Results from the test revealed that, regardless of the vehicle type, increasing glutaraldehyde concentration reduced the toxicity of NR gloves, indicating the reduction of leachable toxic substances after the treatment. Contact angle and water absorption resistance were found to increase with increasing glutaraldehyde concentration, reflecting the enhanced hydrophobicity of the treatment. The mechanical properties of the gloves were not significantly different after such treatment. The results confirm the potential use of this protein crosslinking method to reduce the allergy problem of NR gloves.