Does plastic expands on cooling?

No, plastic expands with heat and contracts with cold. This property is called the coefficient of thermal expansion. All plastic moves to one degree or another and it is very important to keep in mind when designing parts. Especially parts of different materials that have very close tolerances. read more

A little heat will make plastic expand. However, if plastic isexposed to a lot of heat, it will melt since it is a poorconductor. read more

They do it on the expense of length/width to gain height. Take a Rubber band, Stretch and wrap it around something. read more

Yes, if a plastic shrinks upon heating, it will usually expand when cooled within that same range. This phenomenon is known as negative thermal expansion (NTE), and is seen in other materials besides plastics/polymers. Many ceramic oxides (particularly molybdates and tungstates), phosphates, cyanides, and even graphite exhibit NTE. read more