Date: 10th August 2006
Place a birthday candle inside a polystyrene drinking cup, so the cup acts as a windshield for the flame. Spike the base of the candle into the ground. Light the candle. Hold the bottle over the candle until it melts.
The flame melted a hole in the sample. The hole is roughly circular with a thickened edge. The thickening is presumably caused by surface tension drawing the plastic back. A white ring, caused by recrystallisation, is visible around the hole. The crystallisation is rough on the outside of the bottle, though the thickened bit is smooth.
Permanent deformation without recrystallisation has ocured further away from the hole. The plastic is clear in these deformed regions.
Set up a flame as before. This time fill the bottle with water to limit the temperature. Heat the bottle but don't melt a hole in it.
Copyright John Dalton, 2006
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