A comparative study of the tack of Butyl and natural rubbers was made by contacting freshly cut surfaces of the compounds under various time-temperature-pressure conditions and measuring the force required to separate the splice. The temperature of the knife used to cut the samples was found to be of primary importance. The tack of Butyl compounded with 50 parts of semireën-forcing carbon black (no curatives) decreases regularly with increasing knife temperature. Both longer time and higher pressure of contact favor better splicing. Data are presented on the effect of various plasticizers and carbon blacks on the tack of Butyl compounds.
Novel malonate-functional polyesters from biobased and potentially biobased monomers were developed and cured through the base-catalyzed carbon-Michael addition reaction with acryloyl-functional oligomers. Both drop-in monomers, such as fully biobased diethyl malonate, and alternative raw materials, such as isosorbide and vegetable oil, were introduced. Isosorbide-based polyesters show improved performance to humidity in terms of adhesion on epoxy-amine primer, while vegetable oil-containing resins lead to improved coating appearance due to better flow and levelling. This study demonstrates that biobased malonate resins, having renewable contents up to 53%, offer attractive performance benefits in 2K RMA paints. It is anticipated that, with the development of additional fully biobased polyols, renewable contents in excess of 80% can be achieved.
2247creasing the glycol content above about 50%, the decrease in solubility with temperature increase tends to become a little larger even though the actual solubility value is decreasing.A large number of aqueous glycol solvents was employed in order to establish definitely whether there is a reversal of the slopes of the inverted solubility curves.The decrease in solubility with increase in temperature over a wide middle portion of the solvent composition range may be small enough to reduce appreciably the crystalline deposit on the heating element of an evaporator-crystallizer.An inflection point is known to occur at about 125°C. for the solubility curve of the anhydrous salt in water. Since this temperature would undoubtedly be different for the various glycol concentrations, an attempt was made to ascertain whether this inflection point was attainable for any of the solvents at atmospheric pressure. Accordingly, some additional solubility determinations were run above 100°C. with solvents ranging from 0 to 90 weight % glycol. These results are listed in Table IV. A precision of considerably better than ±0.01 weight % salt was required. At given solvent compositions the temperature was lowered from close to the boiling point to a series of equilibrium temperatures at intervals of a few degrees. Tests indicated no appreciable change in solvent composition during the course of any of these runs.The data of Table IV show an apparent inflection point below the atmospheric boiling point for many of the aqueous glycol sol-vents. These are not considered conclusive, however, because of the difficulties of sampling at these temperatures and the very small changes in solubility over the temperature increments involved. Nevertheless, they seem to indicate that an extension of the curves of Figure 4 to the boiling points of the solution would find them practically vertical for solutions with 40 weight % or higher glycol as solvent. The approximate boiling points included in Table IV are intended to indicate the degree to which these limiting temperatures were approached.
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