Unsaturation ratio

Emeis K.-C., Struck U., Schulz H.-M., Rosenberg R., Bernasconi S., Erlenkeuser H., Sakamoto T., and Martinez-Ruiz F. (2000) Temperature and salinity variations of Mediterranean Sea surface waters over the last 16,000 years from records of planktonic stable isotopes and alkenone unsaturation ratios. Palaeogeogr. Paleaoeclimatol. Palaeoecol. 158, 259-280. 

Rontani F.-F., Cuny P., Gossi V., and Beker B. (1997) Stability of long-chain alkenones in senescing cells of Emiliania huxleyr. effect of photochemical and aerobic microbial degradation on the alkenone unsaturation ratio (Ufv). Org. Geochem. 26, 503-509. 

Sikes E. L. and Volkman J. K. (1993) Calibration of alkenone unsaturation ratios (UI7) for paleotemperature estimation in cold polar waters. Geochim. Cosmochim. Acta 57, 1883-1889. 

Sikes E. L., Farrington J. W., and Keigwin L. D. (1991) Use of the alkenone unsaturation ratio UI7 to determine past sea surface temperatures core-top SST calibrations and methodology considerations. Earth Planet. Sci. Lett. 104, 36-47. 

Differences in distribution of lipid fatty acids from chloroplasts of atrazine-resistant and atrazine-susceptible biotypes (18), Resistant Unsaturation Ratio (18 2 + 18 3)... 

The vinyl urethanes are normally derived from hydroxyl-terminated unsaturated polyester alkyds, e.g., propoxylated bisphenol A fumarate, which have been end-capped with a polyisocyanate and then subsequently end-capped with an hydroxy alkyl methacrylate. Thus, these resins have both terminal acrylic and in-chain maleate/fumarate unsaturation, the ratio depending on the oligomer molecular weight and the functionality of the polyisocyanate. High molecnlar weight results in a lower terminal in-chain unsaturation ratio, while a polyisocyanate fimctionality > 2 increases the ratio. A typical oligomer structure is shown in Structure 9.3 [13,14]. 

The practical consequences of an auto-acceleration effect on exotherm and conversion are illustrated by the exotherm curves in Figure 9.1. The urethane methacrylate/methyl methacrylate resin that shows auto-acceleration at all oligomer/monomer ratios is compared with an unsaturated polyester/styrene resin, which only shows an autoacceleration (or gel effect ) at high alkyd/styrene ratios. The urethane methacrylate oligomer copolymerised with styrene shows virtually the same exotherm behaviour as the unsaturated polyester for equivalent styrene/oligomer unsaturation ratios. 

The freedom in monomer/oligomer unsaturation ratio in the all-acrylic functional resins allows crosslink density and hardness/softness properties of the cured polymer to be varied... 

For conjugated fatty acids (1) drying rate varies hyperbolically with increasing concentration of polyenoic acid and increases until the polyenoic acid content reaches half the concentration of total unsaturation and (2) dried film hardness has been shown to be independent of the dienoic trienoic acid ratio and conjugated nonconjugated unsaturation ratio, if the total polyenoic acid content is unchanged. 

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