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Surface Properties of Poly(ethylene terephthalate)
| Title: | Surface Properties of Poly(ethylene terephthalate) |
| Author: | Matthews, Thomas Robert |
| Description: | This study attempted to determine if common processing parameters cause changes in the surface tension of the polymer. Initially, several contact angle techniques were tested to determine the optimal technique to be used for the remaining experiments. From these initial tests, the Harmonic Mean method was selected to determine the surface tension of the polymers. Flat parts were injection molded from both copolymer and homopolymer resins and aged at room temperature and humidity for two months. The surface tension of these parts was measured during several intervals throughout this storage time. The surface tensions of both materials dropped slightly for the first week of storage before leveling off to 44-47dynes/cm. Varying the injection molding conditions did not seem to cause the surface tension to change drastically. Some additional materials were aged for three weeks at 40°C to accelerate the aging process; however this also did not cause a significant change in the surface tension. Films were stretched under various conditions and it was found that increasing the planar extension decreased the surface tension. To determine if this was due to polar end group concentrations on the surface, films were exposed to UV light. The surface tension was found to increase with increased UV exposure time. The end group concentrations for the exposed samples were measured and it was found that the end group concentration increased with exposure time. For times up to 96 hours, the measured end group concentrations correlated well with intrinsic viscosity measurements. Bottles were blow molded under various conditions; it was found that the bottles blown from preforms having the highest temperature had the lowest surface tension. Storage of the bottles at room temperature and humidity caused the surface tension to decrease to around 45 dynes/cm. The films that were stretched to the same level as the bottles had similar surface tensions as the bottles after storage. |
| Permanent Link: |
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1177515548
http://hdl.handle.net/2374.OX/19360 |
| Date: | 2007 |
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