I wouldn't say so. They are often objects in main clauses, "She tried taking the detour," and complements to verbs of being, "The response was alarming," "The car is completely destroyed." (You may always debate whether this is simply passive voice.)
Yes, "determined" is a PP in your sentence. As far as I'm concerned, a PP is always a PP, except when it's simple past tense, and in that case it never was a PP. That is, when it's used as an element in forming another tense, It may still be referred to as the PP. When it's used as an adjective, it may still be referred to as the PP.
Edit. PP = past participle, in this paragraph.
The
Present participal, on the other hand, may no longer be referred to as the present participle when it functions as a noun.