Diffusion of liquids in molten polymers: Mutual diffusion coefficient dependence on liquid miscibility and polymer molar mass

Reactive Processing of Thermoplastic Polymers: A Review of the Fundamental Aspects

“…Since the solubility parameters are generally assumed to be independent on the molecular weight for polymers, the mutual diffusion coefficient should be constant regarding the melt viscosity. Such results were recently confirmed by oil diffusion in molten PP of different melt flow index (MFI = 2 and 12) [229] and diffusion of N-ethylaniline (NEA) monomer [253] in EVA copolymers of different viscosities from 75 to 5.0 × 10 4 Pa s. Van der Wal [254] measured the diffusion coefficient of 7(diethylamino)-4nitrobenz-2-oxa-1,3-diazola (NBD) in PS of different molecular weight at different temperatures above Tg. He found that the diffusion coefficient of NBD in polystyrene (PS) does not depend on molecular weight of entangled PS (Mn = 100 000 and 140 000 g mol -1 ).…”

“…Indeed, the study of the diffusion process of the epoxy (2,3-epoxypropyl-phenylether, EPPE) monomer in molten EVA copolymer showed that as expected the self coefficient D 1 was not dependent on molecular weight of EVA samples whereas the mutual coefficient diffusion D 12 was strongly dependent on the molecular weight of EVA through the dependence of the Flory-Huggins interaction parameter [253]. However, the diffusion process for this latter case is more complicated due to the partial miscibility of the diffusing epoxy molecules with EVA copolymers.…”

“…16 shows the variation of the self diffusion coefficient D 1 and the mutual diffusion coefficient D 12 of N-ethylaniline in EVA copolymer at different temperatures versus the volume fraction of the diffusing amine [253]. They have been calculated with the inverse rheological method described above.…”

Characterization and modelling of diffusion and reaction of low molecular weight reactants in molten polymer

“…They are also difficult to calculate reliably because of the number of parameters involved in the diffusion models. In preceding work we studied the diffusion of methylaniline (NEA) and EPPE in EVAs with different molecular weights [26]. The mutual diffusion coefficient, D 12 , was determined by an inverse rheological method developed by Ponsard-Filette et al [27].…”

“…Table 4 Diffusion coefficients of DPA, EPPE and product in EVA at T ¼ 150 C calculated according to Ref. [26] Reactants' mass fraction in EVA (wt%) Table 3 k and k 0 calculated for pure EPPEeDPA and for 20 wt% of EPPEeDPA dissolved in EVA (T ¼ 150 C)…”