ArticleThe water-retention hydrogel composites were synthesized by the free-radical
polymerization depending on the order of addition filler of the protein hydrolysate. As the filler
was used protein hydrolysate, ‘Biostim’, obtained by processing cattle hides. The influence of
gelation time on the synthesis parameters of hydrogel compositions was investigated. It is found
that the gelation time of the sample without filler is 2–2.5 times longer than filled of hydrogel
compositions. The structural characteristics of polymer composition by TGA, DSC and atomic
force microscopy were determined. FTIR spectra found decrease in the intensity of vibrations of
(-COO-) groups, indicating about additional ionic interactions. Decrease the beginning
evaporation temperature of polymer composites with increase concentration of protein filler,
indicating the destruction of the ordered structure of the polymer material revealed by
thermogravimetric analysis (TGA). The influence of various media, such as distilled water, saline
solution, and buffer solutions at differents pH on the swelling behavior of hydrogels was also
assessed. Maximum swelling capacity showed sample prepared with order of addition filler at the
end of synthesis (Scheme I). The kinetics of the release protein hydrolysate from the polymer
matrix was measurement by spectrophotometric method. The synthesized hydrogel composites
with protein hydrolysate and improved physicochemical properties are of practical interest as
water-retaining materials for increasing of crop the yield in agricultural