26719-48-2Relevant articles and documents
Structural Effects on the Vaporization of High Molecular Weight Esters
Kishore, K.,Shobha, H. K.,Mattamal, G. J.
, p. 1642 - 1648 (2007/10/02)
To understand the effect of molecular weight and branching on the heats of vaporization (ΔHv) and their flow behavior, ΔHv and viscosity (η) were measured at different temperatures in the high molecular weight ester series: linear flexible di-n-alkyl sebacates and compact branched triglycerides with molecular weights ranging from 300 to 900. ΔHv0 values (ΔHv corrected to 298 K) have been obtained with experimental ΔHv and also computed according to the group additivity method; a smaller -CH2- group value of 3.8 kJ mol-1 compared to the normal value of 5.0 kJ mol-1 is found to give good agreement with the experimental data (within 2-5percent error).Both ester series have the same ΔHv0 irrespective of their molecular features, namely, shape, flexibility, and polarity, suggesting the coiling of the molecules during vaporization.The segmental motion of these ester series during their flow and its dependence on their molecular features unlike ΔHv0 are demonstrated by the correlation of the enthalpie of activation for viscous flow (ΔH*) and the ratio ΔEv/ΔH* = η (ΔEv is the energy of vaporization) with molecular weight.
