Fall 2015 CHY482

Fall 2015 CHY482
Take-home final exam
Due date: Monday December 15, 2015 at 1800 via email
The crystallization of materials such as waxes, triglycerides and polymers involves the
nucleation and growth of molten species into an ordered crystal lattice typically as a result of
cooling. During solidification, the surface of newly-formed crystals is surrounded by layers of
molten species that are about to solidify (i.e., in an incipient state of crystallization). To this day,
however, there remains little information regarding the solid-liquid interfacial tension (?sl) that
exists between the solidified material and its liquid-state counterpart. Presumably the value of ?sl
is low (likely well below 1 mN/m), though there exists little scientific validation of this point.
Nevertheless, numerous models over the past few years have tended towards this conclusion.
Taking into account everything that you have been exposed to in CHY482 as well as the large
body of information available in monographs and peer-reviewed scientific journal articles, please
answer the following questions. The % breakdown is shown in brackets following each question:
i) Please provide a definition of ?sl (20%).
ii) What are the intra- and inter-molecular forces at play in ?sl (40%)?
iii) Using the scientific literature on research in many fields as a guide (e.g., polymers,
pharmaceutical, food science, etc.), please provide and describe possible methods that
are (or may be) used to determine ?sl. Your chosen approach(es) may be experimental
and/or computer simulation-based (40%).
You must work individually. Answers to these questions should total 6 pages maximum doublespaced.
Other pages may consist of your title page, references, etc. Within the 6 pages, you may
wish to include figures that assist in conveying a certain point. Please do not feel that you have to
fill the 6 pages! Use 12 pt Times New Roman font and 1” margins. You must include 5 relevant
references in a consistent referencing style. The course notes are one acceptable reference.