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A wide range of infinite urethane polymer networks were prepared from poly(ethy1-ene glycol) (PEG) and hexamethylene diisocyanate (HMDI) using l,l,l-tris-(hydroxymethy1)ethane (THME) as the cross-linking agent. The influence of temperature, cross-linking, and crystallinity on the swelling character of the hydrogel has been discussed. The toxicity of the network polymer by intravaginal implants in rats was studied. Implantation of the polymer did not result in alteration in behavior and feed intake or any pathological changes in the tissue. Vaginal fluids from the polymer-implanted rats or the polymer extract when inoculated on a listeria monocytogene culture plate were unable to inhibit the bacterial growth.

In the subambient thermal volatilization analysis (TVA) technique, degradation products initially at −196°C are allowed to warm up to ambient temperature in a controlled manner under vacuum conditions, and volatilization from the sample tube to a trap at −196°C is monitored by means of a Pirani gauge. The technique is discussed in relation to earlier TVA work in which volatilization from a heated polymer sample was followed. Design and operation of a subambient TVA system are described, and examples of the application of the technique to the study of the degradation products of seven polymers are considered.

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