Definition
A type of plastic that softens when heated and hardens again when cooled, and can be reheated and reshaped repeatedly without changing its chemical structure. Common thermoplastics used in aircraft include acrylic (used for windshields and side windows) and polycarbonate.
Plain English
A plastic that gets soft when you heat it and goes hard again when it cools. You can heat and reshape it as many times as you like.
Context Anchor
Seen in aircraft maintenance and materials discussions, especially when identifying plastics used in windows, fairings, interior parts, or formed panels.
Derivation
From Greek 'thermos' meaning heat, and 'plastikos' meaning able to be moulded. So thermoplastic literally means 'heat-mouldable' — a material you shape with heat.
Why Pilots Care
Thermoplastic windshields and windows can be damaged by heat from sources like hot tools, heat guns, or even prolonged sun exposure on a parked aircraft. They scratch and craze more easily than glass, which affects how they're cleaned and inspected.
Analogy
A simple comparison is wax: when heated, it softens and can be reshaped; when it cools, it becomes firm again. A thermoplastic is more engineered and durable than wax, but the heat-soften/cool-harden idea is similar.
Intuition Check
Thermoplastic does not mean the material is heatproof. It means heat can soften it so it can be shaped.
Example Sentence 1
The cabin windows are made of a thermoplastic material, so avoid using harsh solvents or heat sources near them during cleaning.
Example Sentence 2
Aircraft interior panels often use thermoplastic material because it can be formed to fit curved surfaces during installation.