Sulfonation treatment for a thermoplastic part

A method for applying a sulfonation treatment to a thermoplastic part, the method comprising:

• installing a gas sulfonation assembly on one or more surfaces of the thermoplastic part by forming a vacuum bag on the one or more surfaces, and the vacuum bag forms a sealed cavity between the vacuum bag and a treatment portion of the one or more surfaces;
• drawing a vacuum in the sealed cavity with a vacuum pump of the gas sulfonation assembly;
• directing a sulfonating gas into the sealed cavity with a sulfonating gas source of the gas sulfonation assembly to sulfonate the treatment portion, and the sulfonating gas includes sulfur trioxide, sulfur dioxide, or a combination of sulfur trioxide and sulfur dioxide;
• removing the sulfonating gas from the sealed cavity with the vacuum pump;
• and
• condensing or neutralizing the sulfonating gas with a vacuum trap of the gas sulfonation assembly as the sulfonating gas is removed from the sealed cavity by the vacuum pump.