Publication: Recycling gloves into value-added products: rubber shoe soles
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Date
2025-08-07
Authors
Nur Husnina binti Mohd Azhar
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Abstract
The global demand for nitrile gloves has led to a rejection rate of up to 15% due to defects such as pinholes, air bubbles, and contaminants during the latex dipping process. Disposed nitrile gloves pose significant environmental threats when sent to landfills. This study aims to recycle rejected NBR gloves (r-NBR) into value-added rubber blends with natural rubber (NR) for sustainable shoe sole applications. The main objectives were to evaluate the effect of r-NBR ratios on mechanical properties and to develop an optimal rubber formulation using various curing systems (conventional vulcanization (CV), Efficient vulcanization (EV) and Semi- efficient (Semi-EV) and fillers (calcium carbonate dan silica). The test results showed that the NR/r-NBR blend at a 95/5 ratio was evaluated for tensile strength, elongation at break, hardness, and tear resistance. The CV system with calcium carbonate filler exhibited the best mechanical properties, with a tensile strength of 12.30 MPa, elongation at break of 430%, tear strength of 12.80 N/mm, and hardness of 71 Shore A. This formulation (NR/r-NBR blend at a 95/5 ratio using the CV system and calcium carbonate filler) demonstrated a moderate reduction in mechanical properties compared to the control sample, yet it remained within the acceptable standards for rubber shoe soles, making it an optimal choice that balances performance and the sustainability of recycled materials. This study confirms the potential use of NR/r-NBR blends in shoe sole applications, which can reduce industrial waste and contribute to the development of a more sustainable industry.