Storage Properties of DPNR under Various Conditions

Maintaining the properties of deproteinised natural rubber (DPNR) after the production is critical and essential since it tends to deteriorate after the removal of proteins. During the preparation, transportation and storage, rubber may be exposed to contamination and an unfavourable environment that may affect the properties over time. Therefore, this work was conducted to determine the factors that affect the properties of DPNR during storage. In this work, DPNR samples were prepared with and without the presence of zinc oxide (ZnO) and hydrogen peroxide (H2O2) as contaminants. These samples were then stored under different environments such as opened room temperature (RT), closed RT, chilled and heated. Their physical properties were examined during 76 weeks of storage. NR control sample showed the most stable properties along the storage period studied. Removal of proteins in DPNR samples in overall has reduced its whole properties especially when it was contaminated with H2O2. These properties became worsen when the sample was stored in a hot environment (40 °C). Its properties such as Mooney viscosity and plasticity retention index (PRI) decreased significantly with time and reached below 70 MU and 40 units, respectively. This result was supported by the reduction of their molecular weight, which indicates the degradation of these samples during storage. The results showed that the quality of DPNR could be compromised by the presence of contaminants such as H2O2 during production and would be worsen by improper storage conditions.