There are two types of plastic Thermoset and Thermoplastic. Thermoset burn when heated. Once they are formed they cannot be melted again. Thermoplastic can melt if the temperature is right. They can also burn if to much heat is applied. The reason PVC is toxic is the C in PVC. The C stands for chloride. That is a very bad gas to breath. I can't remember off the top of my head which classification PVC falls in but not all plastics are created equal.
