I have sometimes problem understanding these structures. I just came across this expression:
Materials to make sarin gas and perhaps other toxic chemicals moved freely cross-border from Turkey to Syria.
"Materials to make sarin gas and perhaps other toxic chemicals ." Here we can sense that materials are not the subject which will make sarin and other chemicals by itself.In this context , we can infer that the infinitive clause is used in a way that the meaning is close to "materials which is necessary to make sarin gas and other chemicals".
I will give another example and hence my confusion will be revealed.
The woman to save you
The institution to supervise the process
In these examples , we can safely infer that the subject is nouns which are both followed by infinitive clause. The woman is subject. The institution is subject.
So why there is difference? Am i missing a point? In the very first example I gave , the subject is not clear as it is understood from the context.We don't know the subject. Genereally , in the pattern of noun+to+verb+object i want to be enlightened as to subject-object relations of this pattern.