Migration of additives in polymers

The effects influencing the migration of different small molecular materials in polyethylene (PE) were studied. A decrease in weldability experienced after storage of the polymer at ambient and elevated temperatures was proved to be a result of migration of low molecular mass components of the polymer and some type of lubricants to the surface. Studies of different sorbitol fatty acid esters used as antifog agents in PE revealed that their mobility depends on the length of the hydrocarbon chain, while the antifog performance is influenced by the ratio of the OH groups to the hydrocarbon chain length.