Effects of organoclays on morphology and thermal and rheological properties of polystyrene and poly(methyl methacrylate) blends

Abstract

Morphology, thermal and rheological properties of polymer-organoclay composites prepared by melt-blending of polystyrene (PS), poly(methyl methacrylate) (PMMA), and PS/PMMA blends with Cloisite organoclays were examined by transmission electron microscopy, small-angle X-ray scattering, secondary ion mass spectroscopy, differential scanning calorimetry, and rheological techniques. Organoclay particles were finely dispersed and predominantly delaminated in PMMA-clay composites, whereas organoclays formed micrometer-sized aggregates in PS-clay composites. In PS/PMMA blends, the majority of clay particles was concentrated in the PMMA phase and in the interfacial region between PS and PMMA. Although incompatible PS/PMMA blends remained phaseseparated after being melt-blended with organoclays, the addition of organoclays resulted in a drastic reduction in the average microdomain sizes (from 1-1.5 m to ca. 300 -500 nm), indicating that organoclays partially compatibilized the immiscible PS/PMMA blends. The effect of surfactant (di-methyl di-octadecyl-ammonia chloride), used in the preparation of organoclays, on the PS/PMMA miscibility was also investigated. The free surfactant was more compatible with PMMA than with PS; the surfactant was concentrated in PMMA and in the interfacial region of the blends. The microdomain size reduction resulting from the addition of organoclays was definitely more significant than that caused by adding the same amount of free surfactant without clay. The effect of organoclays on the rheological properties was insignificant in all tested systems, suggesting weak interactions between the clay particles and the polymer matrix. In the PS system, PMMA, and organoclay the extent of clay exfoliation and the resultant properties are controlled by the compatibility between the polymer matrix and the surfactant rather than by interactions between the polymer and the clay surface.

Effect of halloysite on structure and properties of melt-drawn PCL/PLA microfibrillar composites

“…In some cases, suitable modifications can enhance HNT efficiency [17,18]. However, the evaluation of the structure-directing potential of HNT in polymer [19][20][21][22][23] is in its infancy stage, especially in comparison with that of oMMT [24][25][26][27]. Although the application of PLA and other high performance polyesters in the form of short reinforcing fibres [28,29] in polymer-polymer composites could be a radical alternative to the use PCL/ PLA blends, a significant limitation of this method is the difficult dispersion of compliant fibres in the polymer matrix and their relatively poor adhesion to it [30].…”

Effect of organo-modified montmorillonite on poly(butylene succinate)/poly(butylene adipate-co-terephthalate) nanocomposites

“…They revealed that this blend is immiscible but only one T g was observed due to the close proximity of individual T g 's of both PBS and PBAT. Other reports have shown that OMMT can act as compatibilizer for immiscible polymer blends [9][10][11][12][13][14][15] which exhibit remarkable improvement in their properties compared to the pristine polymer or the conventional composite [16,17]. The interlayer cations between the silicate layers such as Na + are exchanged with organic cations to increase the organonophilicity of the clay layers.…”

Synergistic Effect of EG and Cloisite 15A on the Thermomechanical Properties and Thermal Conductivity of EVA/PCL Blend

“…A lot of studies have been done on the influence of organo-clay on polymer blends [17][18][19][20][21] . These studies have shown the organoclay may reside preferable within the bulk of the better compatible polymer, might also become localized at the interfacial region as well.…”

“…The interfacial tension is reduced, the droplets coalescence is inhibited and finer dispersion is obtained. Gelfer et al 21 reported the reduction in particle size of the dispersed phase of the PS/PMMA blends with the presence of organo-modified montmorillonite (OMMT). It was further mentioned by Voulgaris and coworker 18 in their study that the presence of OMMT played the role of an emulsifier in PS/PMMA system and showed that this phenomenon increases the melt viscosity of the blend.…”