Hello everyone?

Has anybody done any research to investigate the influence of moisture content on creep behaviours of polymers? like how retardation time changes with moisture content if a burgers model applied? i have done creep tests for  two materials and fit a burgers model to data. One material shows that retardation time increases with increasing moisture content, while the other one shows retardation time decreases with increasing moisture content.  Before i repeat my tests, can any body be kind enough to give me some theoretical guidance or share me some experience on this topic?

Many thanks