When a noun answers an adverb question, it is called an adverbial objective.
...left Friday for the lake... ("Friday" tells "when")
...spent four hours there... ("four hours" tells "how long")
The terms "full time" and "part time" are used in this manner.
...work full-time for them, not part-time...
MW says that these terms are hyphenated as adverbs.
Happy punctuating!
Margie