VISCOELASTIC BEHAVIOR OF HIGHLY CROSSLINKED POLY(ACRYLIC ACID)

In the reported experiments, the effects of crosslinking upon the dynamic mechanical properties and swelling behavior of poly(acrylic acid) (PAA) have been studied. Materials were prepared by the free radical copolymerization of acrylic acid with varying amounts of the tetrafunctional monomer allyl acrylate (ALA). The results indicated a linear dependence of the glass-transition temperature (T//g) on composition, T//g increasing by similar 43 degree C over the mole fraction range X equals 0-0. 37 ALA. Room temperature (25 degree C) modulus values, as determined by both dynamic and compression methods, were inversely proportional to the initial concentration of ALA. The degree of network formation has been characterized in terms of the molecular weight between crosslinks M//c, and the influence of this parameter on the swelling ratio was discussed.