In both cases the formation of an adduct between the TMA molecule and the C=O moiety is found to be a weakly exothermic reaction that is expected to be reversible at room temperature. Swelling of TMA-Infiltrated Polymers. The atomic structure of the polymers together with the volume and the shape of the computational cell were optimized without any TMA introduced and the density of the polymers is calculated. For PLA the calculated density is 1.180 g cm , close to the experimental density 1.25 g cm -3 . The calculated PMMA density was 1.232 g cm -3 with the experimental density of 1.17 -1.20 g cm . The close agreement with experimental density indicates that the model can be used to estimate the swelling upon infiltration of TMA.