When ice is heated, it melts. When a thermoplastic object is heated, it melts as well.
The melted ice can be formed into a new shape, and it will keep that shape when it's cooled. Similarly, a melted thermoplastic object can be formed into a different shape, and it will keep that new shape when it's cooled.
Thermoplastics have long, linear polymer chains that are only weakly chemically bonded, or connected, to each other. When a thermoplastic object is heated, these bonds are easily broken, which makes the polymers able to glide past each other like strands of freshly cooked spaghetti. That's why thermoplastics can readily be remolded.
The weak bonds between the polymers reform when the plastic object is cooled, which enable it to keep its new shape.
The most common method for making plastics is molding. To make a thermoplastic object, plastic granules known as resin are forced into a mold under high heat and pressure. When the material has cooled down, the mold is opened and the plastic object is complete. When making plastic fibers, the molten resin is sprayed through a strainer with tiny holes.
There is a huge range of uses including plastic wrap, food containers, lighting panels, garden hoses, and the constantly encountered plastic bag.
Thermoplastics are easy to recycle since they can be melted and reshaped into other products. For example, a plastic bottle that contained a soft drink could be reformed into the fibres of a fleece jacket.