Posted: March 7th, 2016
Please respond to all the questions below in your report. Reports should be written like a formal essay: typed and double-spaced. I recommend including spectra where you see fit. I suggest having about 3 pages of written text. When identifying functional groups it is fine to just draw on your spectra instead of listing them in your report(relevant to #2 and #5).
1) Introduction: Briefly introduce FTIR from an instrumental perspective. How does is work? What does it tell us about molecules? What are its advantages and limitations?
2) Identify as many functional groups as you can in the polystyrene spectrum.
3) Compare and contrast the spectra of chlorobenzene(CB) and 1,2-dichlorobenzene(DCB)
4) Determine the approximate integer ratio of the unknown DCB:CB mixture. Explain your reasoning.
5) Identify as many functional groups as you can in the epoxy spectra. Which is the hardener, and which is the resin? Explain your reasoning.
6) Was your resin acid cured or base cured? Explain.
7) By examining the IR bands of the epoxide functionalities, estimate the extent of cure.
8) Summarize the changes in the spectra that occurred during the curing reaction, and describe the likely chemical reactions involved.
9) Hypothetically, how might you use FTIR to determine the “epoxide equivalent” of your material? (The epoxide equivalent is defined as the weight of resin in grams that contains one gram equivalent of epoxy. (Hint: “gram equivalent is old-style nomenclature that refers to…what?)
10) How might the final resin differ in structure had you used a higher temperature to cure material?
11) What chemical properties of epoxies cause them to be good adhesives – that is, why do they work?
12) What other instrumental technique could you have used to help you figure out the chemical nature of the hardener, resin, and curing process? Explain.
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