Compatibilization mechanism induced by organoclay in PMMA/PS blends

Abstract

In this work, the effect of adding organoclay (Cloisite 20A) to a poly(methyl metacrylate) (PMMA)/polystyrene (PS) blend was evaluated in order to understand the compatibilization mechanism taking place. The blend morphology was quantified using micrographs obtained by scanning electron microscopy and observed by transmission electron microscopy. The state of dispersion of the clay was studied using small angle X-ray scattering and wide angle X-ray scattering and by applying the Carreau-Yasuda with a yield stress model to small amplitude oscillatory shear (SAOS) data. Morphological analyses revealed that the clay was intercalated, that its addition resulted in a decrease in the size of the dispersed phase and that it was preferentially located at the interface, except in the case of saturated interfaces, in which case the remaining clay was dispersed in PMMA. By applying the simplified Palierne model to SAOS experiments, the interfacial tension between the polymers forming the blend was inferred and shown to decrease upon addition of clay. The relaxation spectra inferred from the SAOS data, using the Honerkamp and Weese method, revealed four relaxation times: Relaxation of PMMA and PS chains, relaxation of the droplet shape, as well as an additional relaxation phenomenon attributed to the Marangoni stress. Although Marangoni stresses have already been studied in the case of blends compatibilized by block copolymers, this is the first time that it has been evidenced in the case of a clay as compatibilizer. V C 2017 The Society of Rheology. [http://dx

Influence of the molar masses on compatibilization mechanism induced by two block copolymers in PMMA/PS blends

“…5, the interfacial tension of each blend can be calculated. The interfacial tension between PMMA and PS can be found in the literature to be between 1 and 3 mN/m [8,15,29,31]. The values found here are of the same orders of magnitude, which decrease with the addition of BC1 but increase with the addition of BC2 (see Table III).…”

“…5(c). To verify this assumption, other rheological measurements were conducted at lower temperature: As already shown by Genoyer et al [29], Marangoni's relaxation is influenced by temperature. By decreasing the temperature, the movements of BCs at the interface will be longer as the viscosity increases.…”

“…Components were blended at 200 C and 50 rpm after PMMA was dried at 80 C for at least 12 h. Blends were prepared in two steps: First, the BCs were mixed with the minor phase (PS) in direct extrusion mode, and then, PS þ BC was mixed with PMMA for 7 min in cycle extrusion mode. The aim was to follow a process similar to another work [29]. In the case of the uncompatibilized PMMA/PS blend (without BC, called pure in the rest of the paper), the minor phase was processed twice in order to ensure it had the same thermal history as the others.…”

Correlation between morphology, rheological behavior, and electrical behavior of conductive cocontinuous LLDPE/EVA blends containing commercial graphene nanoplatelets

“…Furthermore, in many cases, the incorporation of particles in the blends and their selective localization often induces changes in the blend's morphology. In particular, their localization at the interface effectively suppresses coarsening and promotes refined and stable blend morphologies [27,29,[41][42][43][44][45]. In the same context, it was found that plate-like fillers, among them graphene, can adapt better to polymer-polymer interfaces and are subsequently more efficient in suppressing coarsening [42].…”

Effect of clay particles size and location on coalescence in PMMA/PS blends

“…Generally, upon addition of a compatibilizer and irrespective of its chemical nature, one or several of the following phenomena can be observed in the case of a blend with a droplet dispersion type morphology: reduction of the droplet size [21], [22], inhibition of droplet's coalescence [23]- [27], decrease in interfacial tension [28]- [32], and presence of an additional relaxation phenomenon [28], [32]- [40]. The additional relaxation phenomenon observed upon addition of compatibilizers is known to correspond to the relaxation of Marangoni stresses induced by a non-homogeneous concentration of compatibilizers at the interface [34], [39]- [41].…”