The viscoelastic relaxation mechanism of inorganic polymers. III. The sodium polyphosphates

Abstract

AbstractThe sodium polyphosphates represent a class of materials in which the viscoelastic relaxation mechanism in the glass transition region (≈300°C.) could be either molecular flow or bond interchange. At room temperature in aqueous solution these polymers behave like the normal organic polymers in which only molecular flow is encountered, whereas in the melt at 65°C., bond interchange is known to occur. To elucidate which of these two mechanisms is responsible for the relaxation behavior of the polyphosphates, two studies were undertaken. In the first, the viscoelastic properties were investigated as a function of the chain length and of the nature of the terminal units. The results indicated that molecular flow was the mechanism responsible for the relaxation behavior. In the second study, radioactive low polymer was mixed with inactive high polymer, and the mixture separated chromatographically after heating. No evidence of interchange was found here either, confirming the result of the first study.