A coalescence mechanism for the coarsening behavior of polymer blends during a quiescent annealing process. II. Polydispersed particle system

Role of block copolymer on the coarsening of morphology in polymer blend: Effect of micelles

“…In the coalescence mechanism suggested by Fortelný et al, n ranges from 3/2 to 5, depending on the mobility of interface and the driving force of coalescence such as gravity, Brownian motion, and van der Waals forces. The contact coalescence suggested by the present author predicts an almost constant coarsening rate ( n = 1) at low volume fraction, low interfacial tension, and high matrix viscosity, and the rate of coarsening is proportional to the interfacial tension and inversely proportional to the bulk viscosity. Such model implies that suppression of coarsening can happen either when the viscosity increases or the interfacial tension decreases.…”

“…In our case, large molecular weight of copolymer generates , which is large enough (>>20) that spontaneous micelle dissolution and reformation can be negligible at the equilibrium critical micelle concentration . Actually, in theories concerning the coarsening of droplets, the contact probability is a statistical value depending only on the volume fraction and the droplet size, where the process of getting touched is regarded to be faster than the drainage and merging process. The formation of micelles does not change the nearest‐neighbor distribution of droplets, but slows down the translational motion of droplets by decrease the apparent diffusion coefficient.…”

“…According to the theoretical models, the other possible effect is the reduction of interfacial tension due to the distribution of copolymer at the interface. The amount of graft copolymer POE‐ g ‐PS is determined by a two‐step Soxhlet extraction using solvents of POE and PS, respectively.…”

“…The more important compatibilizing effect of copolymer is the retardance of coarsening both under shear flow and quiescent condition . As interfacial tension controls the time scale of film drainage and droplet merge, its reduction also slows down the rate of coalescence according to several coalescence models . The Marangoni stress has been suggested to retard the matrix film drainage and stabilize the morphology .…”

Comportamento Viscoelástico Linear e Morfologia de Blendas PP/HDPE

“…A coalescência depende de dois parâmetros principais: do número de colisões das gotas e da habilidade da blenda de drenar o filme da fase matriz existente entre duas gotas da fase dispersa até que uma espessura crítica é alcançada para que a coalescência ocorra [19,20] : quando o número de colisões das gotas da fase dispersa e a habilidade de drenagem do filme é alta, a coalescência pode ocorrer em baixas concentrações de fase dispersa. O número de colisões das gotas é proporcional ao quadrado da concentração da fase dispersa e é inversamente proporcional ao tamanho da gota.…”