The efficiency of a plasticizer is the amount of that plasticizer needed to produce a finished part at a given hardness or flexibility.
(The efficiency of a plasticizer; is; the amount of that plasticizer) (that plasticizer; needed; to produce a finished part at a given hardness or flexibility)
The efficiency of a plasticizer that plasticizer
is needed
the amount of that plasticizer
to produce a finished part at a given hardness or flexibility