Definition
A substance added to a material — typically a plastic, paint, sealant, or composite resin — to make it softer, more flexible, and less likely to crack. In aircraft maintenance, plasticizers are found in components such as transparent plastics (windows and canopies), dopes used on fabric-covered surfaces, and various sealants and coatings.
Plain English
An additive mixed into a material to keep it pliable instead of brittle. Without it, the material would harden and crack over time.
Context Anchor
Seen in aircraft maintenance when discussing plastics, rubber parts, fabric coatings, sealants, and other materials that must stay flexible.
Derivation
From 'plastic' (able to be shaped or molded) plus the suffix '-izer' (something that causes a property). Literally, 'something that makes a material plastic.' This helps make sense of its job: it gives a stiff material the ability to flex and stretch without breaking.
Why Pilots Care
As aircraft transparent plastics and dopes age, plasticizers slowly leach out. The material then becomes brittle, yellowed, or prone to crazing and cracking — which is why old canopies, windshields, and fabric finishes need careful inspection and eventual replacement.
Intuition Check
Do not read “plasticizer” as meaning “something made of plastic.” Here it means an added chemical that makes another material more flexible.
Example Sentence 1
The technician noted that the older windshield had lost much of its plasticizer, leaving it brittle and prone to crazing.
Example Sentence 2
Over time, plasticizer can migrate out of older plastic parts, leaving them brittle and more likely to crack.