Abstract
Mechanism for the formation of a solid solution and its modification phenomenon were examined in the binary systems of C18-C16, C18-C14, C18-C12, and C16-C14, using differential scanning colorimetry (DSC) and infrared (IR) spectroscopy.
1) Binary systems of C18-C16, C18-C14, and C16-C14 form continuous solid solution in either metastable state or stable state. At transition, they transit from sub-α and α-type solids to β-type solids, and this behavior was similar to that shown by 1-monoglyceride alone. C18-C12 system does not form a solid solution, and C18 and C12 were found to undergo transition independently.
2) Phase diagrams of C18-C16, C18-C14, and C16-C14 systems showed a similar pattern. Transition curve from sub-α to α-type was characteristic, the lowest temperature appeared at a specific composition ratio of the two components, and this temperature differed according to the composition ratio of the two camponents. Since C18 and C12 did not dissolve with each other, transition curves of C18 and C12 were different curves.
3) Transition rate was affected by the molecular chain length comprising the binary system, and became slower in the order of C18-C16, C18-C14, and C16-C14. The transition rate was the fastest in the case of short-chain monoglyceride containing 510% of longchain monoglyceride, but the rate becomes slower as the transition temperature from α to β-type becomes higher, so that, in general, the rate becomes faster with larger amount of short-chain monoglyceride contained in the long-chain monoglyceride, and became slower in the case of contrary.
