Tensile creep properties of interpenetrating networks containing gelatin and poly(ethylene glycol) diacrylate.

The tensile creep properties of an interpenetrating networks (IPN) system containing polyanionic ethylenediaminetetraacetic dianhydride (EDTAD)-modified gelatin and poly(ethylene glycol) diacrylate (PEGdA) of 600 or 2000 Da at various weight ratios were determined under different pH and load levels. A computerized creep testing device was designed following ASTM D2990 and validated to establish the environment-dependent structure-function relationship of IPNs. IPNs containing PEGdA 2000 Da or EDTAD-modified gelatin showed less strain than those formulated with PEGdA 600 Da or unmodified gelatin, respectively. IPN formulated with 40 wt% gelatin showed higher strain than those with 50 or 30 wt% gelatin. Increasing strain in IPN was observed with increasing load level. IPN strain was higher at pH 7 when compared to pH 4 or 10. The creep characteristics of this complex macromolecular system are dependent on both environmental and composition factors.