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I. INTRODUCTION Liquid detergents make a major contribution to the overall detergent and cleaners market, due in part to their handling characteristics and their ease of use. However, in numerous cases, the formulations would lack either consumer appeal or essential physical properties if they did not include additives to modify their viscosity or rheology. Generally speaking, viscosity build is required to improve the aesthetics of a formulation and meet the demands of consumers, for whom the concept “thicker is better” often remains valid [1]. This is especially true in those liquid formulations where the resulting viscosity without additives is barely above that of water itself. A simple increase in viscosity, though, is often not sufficient to meet the technical demands of a formulation. To address these needs, the rheology of the system has to be taken into consideration, and this is intimately bound up with the nature of the formulation, as well as its intended delivery system and its use.Thus, a scouring cream will require suspending properties to prevent the finely divided abrasive from precipitating, yet it must be pourable or squeeze-dispensable from its package. Similarly, a spray cleaner will require a low viscosity under conditions of high shear in order to facilitate the passage through the spray or trigger mechanism. In the case of a wall or bathroom cleaner, a certain degree of “vertical cling” will be needed to maximize the contact time between the formulation and the surface. All these properties can be obtained through the appropriate choice of rheology modifiers [2].

The vapor pressures of isotopic fluoroforms 12CHF3, 13CHF3, and 12CDF3 have been measured at temperatures between 125 and 212 K in a modified Bigeleisen–Brooks–Ishida–Ribnikar cryostat. At all temperatures of measurement P(12CHF3)≳(12CDF3) and P(12CHF3)

A 20 mmole quantity of methyl-13C fluoride at a 13C-enrichment level of 90% was prepared by a two-step synthesis starting with methanol-13C. The overall yield was 60% of methanol used. A series of gas-chromatographic treatments using Ascarite, silica gel, and Chromosorb-102 columns yielded a highly purified methyl fluoride in which the major impurities were less than 10 parts per million of carbon dioxide and 10 parts per million of methyl chloride.

The vapor pressures of isotopic fluoroforms 12CHF3, 13CHF3, and 12CDF3 have been measured at temperatures between 125 and 212 K in a modified Bigeleisen–Brooks–Ishida–Ribnikar cryostat. At all temperatures of measurement P(12CHF3)≳(12CDF3) and P(12CHF3)