International. Researchers at Karlstad University in Sweden have studied the effects of phase interaction of starch-based barrier coatings and polyvinyl alcohyl for flexible packaging papers.
Corn and potato starches modified with octenyl hydroxypropylate and succinate were mixed with regular polyvinyl alcohol and modified with ethylene to increase water vapor barrier properties and increase the flexibility of starch coatings, in order to achieve superior barrier performance.
The phase separation between starch and polyvinyl alcohol was studied in detail – both in the solution and in dry coatings on paper. The barrier performance of coated paper was evaluated with respect to the transmission rate of water vapor. The conditions for the creation of a thin surface layer consisting of only one of the pure polymers were identified and discussed in terms of phase separation in the migration in polyvinyl alcohol solution to the upper surface layer. Phase separation promoted low water vapor transmission rates also with a fairly high fraction of starch in the coatings.
Source: www.sciencedirect.com
