Model Dichotomous Key for Plastics Identification

The purpose of this study was to investigate selected plastics when treated by means of heat, fire, solvents, and specific gravity tests for the development of a model dichotomous key. The study included: (1) a review of literature that contained a brief historical overview of plastics, an examination of their uses, advantages, and chemical make up, and the selection of four tests to be conducted that would reveal characteristics of the plastics, (2) an explanation of the equipment, materials, and procedures for each of the tests, (3) an analysis of the data obtained from the tests, and (4) a recommendation on how to use the plastics dichotomous key. Methods Specified plastics were donated for testing purposes by several plastics manufacturing companies. The plastics were cut to size and used as samples in four tests. These tests included the effects of heat, the fire test, the effects of solvents, and specific gravity. The test data was analyzed and arranged into a basic dichotomous key format. Conclusions The conclusions for this study are as follows: (1) A form of media is needed to help individuals identify common plastics; (2) a propane torch is too powerful of a flame source to use in the fire test; (3) discrepancies in the colors of the flames between the writer\u27s findings and reports from other sources were caused by an incomplete observation of the total flame on the writer\u27s part in the fire test; (4) contaminated solvents may have caused difficulties in determining effects on some of the plastics; and (5) specific gravity results may have been affected by inaccurate balance scale and graduated cylinder readings. Recommendations The following recommendations have been suggested for this study: (1) A gentler flame source, such as the Bunsen burner flame, should be used in the fire test; (2) all parts of the flame should be noted and recorded in the fire test; (3) fresh chemicals should be used for each test conducted in determining the effects of solvents; (4) because of its tendency to curl and stick to the sides of the graduated cylinder, cellulose acetate should be tested in a form other than photographic film in the specific gravity test; (5) to determine the identity of the plastics samples, testing and comparison of characteristics should follow the same order as that of the dichotomous key; and (6) a pilot study should be conducted using the dichotomous key as a testing instrument to be used determine the key\u27s validity. A questionnaire would to provide supplementary information