Demonstration-Ordered
Polymers
The introduction of some of the aspects of organic chemistry into the High School cumculum requires the extensive use of demonstrations. We have found the following1 to be particularly effective in demonstrating the relationship between an increase in the order and the strength of a polymeric material. In the process of drawing a polymer filament, as in the cold drawing of Nylon, the polymer molecules become extended and line u p with a concomitant increase in the number of intermolecular interactions, and the properties (strength) of the filament improve.2 Apparatus and Procedure ?hlb spaghetti (linguine) boiling water pinch salt3 1tsp vegetable oil or butter Cook the spaghetti in boiling salted water until it reaches the proper consistency (a1 dente to spaghetti aficionados). Drain and rinse with cool water, add oil and mix. The demonstration is exceedingly simple. The demonstrator simply dumps the spaghetti on the demonstration table and points out that each strand represents a polymer molecule. The "molecules" are obviously randomly oriented. The demonstrator then grasps two handsful of the spaghetti. As he draws his hands apart it is obvious that few of the "molecules" span the gap, they are easily broken, the "polymer" is weak. An ordered "polymer" can be made by the simple expedient of combing the "polymer" with the fingers. Now when the "polymer" is grasped with both hands a sheaf of "molecules" connect the hands. The ordered "oolvmer" is ohviouslv stroneer than the disordered one. If the "oolvmer" , is now allowed to hung vertrually rrum one hand it laapparent rhat a large numher of the moler~rlrsextend from the pulymer hundlc. A gentle rug wll he suffirienr to remwe these fmm the rrmaindrr of the polymrr, i e . , they are onl) held hg "intermolecular forces" not by the hand.
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IA form of this demonstration is included in the teacher's guide to "Form and Function, An Organic Chemistry Module in the IAC Program." =Morgan, P. W., andKwolek, S. L., J. CHEM. EDUC., 36,182 (1959); Price, C. C., J. CHEM. EDUC., 36,161 (1959). %alt and butter are optional and should be used if the demonstration material is to be used for later consumption. We prefer the use of vegetable oil when multiple demonstrations are planned. The demonstration material proved to be perfectly stable in a plastic container stored in a suitcase during a two-day trip to the ISTA-SSMA 1972 Joint Convention in Chicago. P a u l H. Mazzocchi
University of Maryland College Park, 20742
Volume 50, Number 7,July 1973
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