i did an experiment in class about stretching plastics and i need to explain why some of the plastics were stronger than others!i know its something to do with short and long molecules but yeah...!! help me please :):):thatnkyou!xxx
When you stretch plastic, it heats up. This heat causes a change in the molecular structure of the plastic allowing it to stretch. The stronger a bit of plastic is, the more tightly bound the molecules are. Different plastics have different melting points as well. A few types of plastic that you might deal with every day are HDPE (plastic bags and milk jugs), Polycarbonate (clear plastic drink cups) and PET-E (soda bottles) Each of these plastics start to soften at about 300F (degrees Farenheit) HDPE becomes molten (liquid like and able to be formed) at about 350F Polycarbonate at about 400F PET-E at about 375F If I remember correctly. Anyways, I hope the explanation of melting points and heat help to explain why some plastics are stronger. In some cases the thickness of the material matters as well.
