The Influence of Azidated Glycerol as a New Low Temperature Stabilizer on the Colloidal Properties of Natural Rubber Latex: For Latex Marine Transportation

Abstract

Natural rubber latex (NRL) is normally transported to a destination in colloid/liquid form. It requires large storage containers such as drums and the probability of latex leakage during transportation is high. This is prevalent especially when transporting latex by sea. To prevent latex spillage, the liquid form of NRL is transformed into solid/frozen latex by freezing. However, the coagulation/destabilization of NRL by freezing has been acknowledged as a problem for years. Therefore, this study proposed a new low temperature stabilizer named azidated glycerol (AG) to be incorporated in NRL liquid before the freezing process. AG was prepared by a chemical reaction of pure glycerol with sodium azide. NRL containing AG was then frozen at a temperature of −4 °C. After 24 h of freezing, the frozen latex was thawed at ambient temperature for 1 h followed by heating in a water bath at 40 °C for another 1 h. The regenerated latex was then allowed to stand at room temperature before testing. The effect of AG on the colloid properties before and after the freeze–thaw processes was studied. The production of AG was confirmed by the appearance of a peak in the range of 2160–2120 cm−1, corresponding to N=N=N stretching, confirming the introduction of an azide group into the glycerol molecule. Modifying NRL with AG did not significantly influence the TSC of latex. Increasing the AG content up to 0.4 phr resulted in an increase in MST from 699 s to 828 s. An AG content of 0.2 phr resulted in the highest anionically stabilized latex as indicated by zeta potential values of −59.63 mV (before freezing) and −56.27 mV (after thawing). It is concluded that the AG produced in this study can be used as an anti-freeze stabilizer for NRL and is suitable for latex marine transportation.