What type of plastic becomes pliable above a specific temperature and solidifies upon cooling?

Thermoplastics are a type of plastic that becomes pliable when heated above a certain temperature. This property allows them to be molded and shaped during the manufacturing process. Upon cooling, thermoplastics solidify and maintain their new shape. The ability to be repeatedly heated and reshaped without undergoing any significant chemical change is one of the defining characteristics of thermoplastics. This makes them versatile and widely used in applications ranging from packaging to automotive parts.

In contrast, thermosetting plastics harden permanently when cured or set and cannot be remolded after their initial forming, making them unsuitable for processes where reshaping is required. Acrylates, while a specific type of thermoplastic, do not encompass the overall characteristics of all thermoplastics. Composites refer to materials made from two or more constituent materials with significantly different physical or chemical properties, which results in a material with characteristics different from those of the individual components. Therefore, the distinction and properties of thermoplastics align perfectly with the phenomena described in the question.