Assignment 6 Experiment on Plastics by Burning test

Assignment 6 Experiment on Plastics by Burning test Done by: Jap Xin Yi

Experiment 1. When I burnt the copper plate, I could see the green flame appeared after a few seconds. I did not see any blue flame as what Prof. have mentioned.

Experiment 2. Polyvinylchloride ( PVC ) Then, when I burnt the Polyvinylchloride ( PVC ), I could see some orange-blue flame while the PVC started to become black and melt. Then, after a few minutes, the flame started to become blue-green. Can Prof. explained about the changing color of the flame? ?

Experiment 3. Polyethylene ( PE ) When I burnt the plastic bags, which is considered as polyethylene ( PE ), I could see the green-orange flame.

Experiment 4. Polystyrene ( PS ) When I burnt the polystyrene ( PS ), I could see the fire is very big, and the flame colour is orange-green. It is same like the polyethylene ( PE ). Why the color is same, but just the condition of the fire not the same, is it because of the chemical properties of them is almost the same and cause the wavelengths are common?

Experiment 5. Polypropylene( PP ) When I burnt the polypropylene ( PP) , I could see the green-orange flame at first, then I see a little blue flame appeared. . It is so beautiful ad amazing!!

Experiment Why can we see the flame which has different color? ? For my opinion, I think that plastic has different chemical composition; plastic can often easily ignite when exposed to sufficient heat in the presence of oxygen. Because of the different chemical properties of plastic, their wavelengths are also different. This enables us to see different color of the flame. The visible colours of the flame have reflected the visible light. As I said before, the human eyes are made up of receptors, the rod cells and cone cells on retina that can detect light energy of certain wavelengths [(4. 0 – 7. 5 ) x 10 -7 m]. Human eyes can only detect visible light which is only a small portion of the electromagnetic spectrum. The visible light corresponds to a wavelength range of 400 - 700 nanometers (nm) and a color range of violet through red. The human eye is not capable of "seeing" radiation with wavelengths outside the visible spectrum.

Experiment The other possibility is the energy transferred by the particles in the plastic. Plastic is a molecular structure component. Therefore, they are bind together with a covalent bond. During the combustion of the plastic, it will produce energy. Different energy value transferred by the particles will also produce different color of the flame. By measuring the surface tension values, we could calculate the surface energy of the plastic. Surface tension values for some plastics Material Surface tension (m. N/m) Polypropylene 29 Polyethylene 31 Polystyrene 35– 37 PVC 39 For there, we could see that polypropylene and polyethylene have low surface energy while polystyrene and PVC have the highest energy value. Hence, different energy value influences the colors of the flames.

Questions: • Prof. , if we burn recyclable plastics, what will become to the colors of the flame, and will it endanger our health? ? The energy value will be high or not? • Prof. what will be the flame colors if heat resistant plastics are burnt ?