Raw rubber properties and mechanical properties of smoked sheet rubber made from natural rubber latex preserved using ammonia

A study was carried out to understand the processing behaviour of smoked sheet rubber manufactured using natural rubber field latex (NRFL) preserved using ammonia at different concentrations. The NRFL preserved with sodium sulphite was used as a control together with un-preserved NRFL. The NRFL preserved using different ammonia concentrations were kept for different time intervals before further processing. Sheet rubber was manufactured using the preserved latex according to the standard manufacturing procedures. Preservation ability, acid requirement for coagulation, drying characteristics, and the raw rubber properties and mechanical properties of sheet rubber were evaluated. The results revealed that the ammonia concentration should exceed 0.15% to keep the latex for more than a day without pre-coagulation. As the ammonia concentration is higher, the acid requirement was higher. Sheet rubber manufactured using ammoniated latex takes marginally longer time to reach complete dryness. The ammonia concentration and time of preservation has a significant effect on raw rubber properties other than un-aged rapid plasticity number. There was no significant effect (p>0.05) on the mechanical properties other than aged-tensile, tear properties and rebound resilience at aged state.