I need to work out the mass fraction of plasticizer absorbed by a polymer. I know the initial Tg of the polymer, the Tg after the plasticizer has been absorbed, and the Tg of the plasticizer itself. I know the equation is 1/Tg = W1/Tg1 + W2/Tg2, but can't figure out how to get the mass fraction of plasticizer (W1) or polymer (W2). Thanks in advance.