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SYNOPSISSupercritical fluid (SCF) technology involving carbon dioxide is recently receiving wide attention due to its vast potential application in various fields such as cleaning, extraction, synthesis, etc., in addition to its environmental benefits. T o fully exploit the use of SCFs in new technologies, it is important to understand how SCFs interact with materials. T o this end, we have undertaken a systematic study involving a wide pressure and temperature range to investigate the interaction of supercritical carbon dioxide (SC C02) with nine different crystalline polymers, namely, substituted and unsubstituted polyethylene (four varieties), polypropylene, nylon 66, poly(ethy1ene terephthalate), poly(oxymethylene), and poly(viny1idine fluoride). Critical factors such as changes in appearance and weight, temperature, pressure and time of the supercritical fluid treatment, and dimension of samples have been observed. The influence of SC C 0 2 on the thermal properties of treated polymers has been investigated through TGA analysis. Further, changes in the mechanical properties such as yield strength, ultimate elongation, and modulus of elasticity of the investigated crystalline polymers were also observed. A discussion has been included to show the possible implications of the observed changes in realizing various applications. 0 1996 John Wiley & Sons, Inc.

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In continuation of our goal to implement supercritical fluid (SCF) technology for various applications such as precision cleaning, foaming, and impregnation of materials, a systematic study has been performed involving amorphous polymers. Eleven different polymers of amorphous nature have been subjected to supercritical carbon dioxide (SC CO2) treatment under a wide pressure and temperature range (1000–3000 psi and 25–70°C, respectively). The influence and impact of such treatment on the appearance, weight change, and thermal and mechanical properties were followed systematically. In addition, the effect of treatment conditions and dimension of the samples on weight changes were also monitored. It has been found that amorphous polymers can absorb carbon dioxide to a greater extent than crystalline polymers and, in turn, the phenomenon of plasticization was also very high. In addition to morphology, the polarity of the polymer is also crucial in determining the solubility in carbon dioxide. Comparison was also made with the behavior of crystalline polymers. © 1996 John Wiley & Sons, Inc.

Proteins have been successfully extracted from the fossil vertebra of a 150-million-year-old sauropod dinosaur ("Seismosaurus") recently excavated from the Morrison Formation of New Mexico. HCl and guanidine.HCl extracts of the fossil bone and its sandstone matrix were concentrated, demineralized, and resolved into a number of different protein fractions by reversed-phase high-performance liquid chromatography (HPLC). One of these fractions had the same retention time as collagen. Amino acid analysis (Pico-Tag method) of these fractions confirmed they were proteins. Comparison of the correlation coefficients of the amino acid analyses with that of collagen standards indicated that none of the fractions contained significant amounts of collagen. Similar HPLC profiles were obtained for the HCl extracts of fossil bone and its sandstone matrix suggesting they contained the same proteins. However, different HPLC profiles were obtained when these HCl extracts were dried and reextracted with guanidine.HCl. These different fractions represent proteins unique to the fossil and were not found in the sandstone matrix. These differences were confirmed by amino acid analysis. Such information on fossil bone proteins might provide useful knowledge concerning the evolution of skeletal molecules and the fossilization process. Similar information on the proteins from the geological matrix might provide useful fingerprints for reconstructing ancient environments and for assessing sedimentary rocks for fossil fuel exploration.