Energy densities of fuels produced from plastic that has undergone thermal depolymerisation in the absence of oxygen
Dustin Riley
Mulgrave School
Floor Location : S 193 E

The purpose of this experiment was to test which types of plastic produce the most energy dense fuel after going through thermal depolymerization in the absence of oxygen, or commonly referred to as anhydrous pyrolysis. The plastics used for this test were polyethylene, polypropylene and polyvinylchloride. All of the different types of plastic were ground and put in an airtight steel boiling unit that was self-designed, and built by a professional iron worker. The plastic was then heated up to about 350C0 for about one hour. This is roughly when all the plastics stopped producing visible oil bubbles. Every type of tested plastic did produce oil, but the quantity varied dramatically from 10 grams for polyvinylchloride to close to 150 grams for polyethylene. These samples were separated into three 3 gram tests, and were tested for their energy content using calorimetry. The energy densities varied from 0.66MJ/Kg to 3.62MJ/Kg, polyvinylchloride producing the least energy dense fuel, and polyethylene producing the most energy dense fuel. In addition, a sample of gasoline was tested to see how accurate the in lab enthalpy tests compared to a commercial fuel. The fuels were also found to have varying colours, and opacity. Polyethylene fuel had a light brown colour, polypropylene had a yellow colour and polyvinylchloride was almost completely black. Also polypropylene was the least opaque fuel, while polyvinylchloride was almost completely opaque.