The kinetics of water sorption by starch filled polyolefins has been i
nvestigated using blends of a commercial starch masterbatch with low d
ensity polyethylene (LDPE), high density PE (HDPE), and copolymers of
ethylene with methyl acrylate (EMA), ethyl acrylate (EEA), and n-butyl
acrylate (EEA). Transient state diffusion coefficients (D) of water i
n the blends were determined using Fickian analysis of the initial sta
ges of the sorption isotherms. Measured D values were several orders o
f magnitude lower than values reported for either pure starch or LDPE
by various investigators. Resin effects on D were in the order D-HDPE
< D-LDPE much less than D-EBA < D-EBA < D-EMA. The resin effects dimin
ished as the starch content increased. The lower magnitude of D in the
blends relative to pure LDPE was attributed to the sorption of water
by the dry starch particles, in a manner similar to dual-mode sorption
in glassy polymers. Copolymer effects were consistent with reduction
in crystallinity caused by the comonomers. The dependence of the diffu
sion coefficient on starch content was not described by mixing models
of heterogeneous systems or percolation theory.