Freeze-Thaw Stability of Natural Rubber Latex Concentrates

Manufacturer: We are using centrifuged latex concentrates from Thailand and very often encountering latex stability problem during winters. Can you explain why and how we can ensure better freeze-thaw stability of the latex.
 
John Woon (Senior Latex Consultant): If you are storing your latex just above freezing temperatures, the colloidal stability of the latex is normally still acceptable. But once the water phase of the latex is frozen at sub-zero temperatures, latex destabilization would occur with an increase in viscosity and a drop in mechanical stability even after the latex has been thawed.

The frozen of the water phase would force the latex particles to collide and adhere with each other and hence destabilization. In severe cases, this would lead to irreversible coagulation and gelation.

The good news is that freeze-thaw stabilized centrifuged latex concentrates are available from the latex producers if such requirement is specified by the buyers. The improved stability is normally done through the addition of sodium salts of certain phenolic additive and ammonium laurate soap.