Polypropylene/clay nanocomposites: Combined effects of clay treatment and compatibilizer polymers on the structure and properties (original) (raw)
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Applied Clay Science, 2015
In the present work, sodium bentonite was chemically modified with alkyl aluminum compounds to prepare polypropylene nanocomposites containing nanosized clay with homogeneous morphology. The compounds were compared with PP/commercial organoclay containing alkyl ammonium ions. Both unmodified and modified bentonite compounds were incorporated in a commercial PP matrix and maleated PP (PP-MA) as coupling agent was also mixed by melt intercalation using a mini-extruder. The obtained clay/polymer nanocomposites (CPN) were characterized by differential scanning calorimetry, X-ray diffractometry, thermodynamic-mechanical analysis and thermogravimetry. According to the results of the method developed in this study, the prepared PP-nanocomposites containing clays with different chemical treatments exhibited an increase of the d-value of the clay in the XRD, and resulted in much better properties, like increased degradation temperature and mechanical parameters, compared with those of the polymer without clay and of the materials with untreated clay. Also, treatment with triethylaluminum was most efficient.
Materials & Design, 2010
The morphological, physical and mechanical properties of polypropylene/clay nanocomposites (PPCNs) were prepared by in situ polymerization are investigated. Non-modified scmectite type clay (e.g. bentonite) was used to prepare bi-supported Ziegler-Natta catalyst of TiCl 4 /Mg(OEt) 2 /clay. Exfoliated PPCNs were obtained by in situ intercalative polymerization of propylene using produced bi-supported catalyst. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) micrograph were used to assess the clay morphology and dispersion of clay. The crystalline structures of PPCNs were characterized by differential scanning calorimetry (DSC). The mechanical properties of PPCNs were studied by tensile and impact tests. thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis DMTA were used to characterize the thermal and dynamic mechanical properties, respectively. The thermomechanical properties of prepared nanocomposites were considerably improved by introducing small amount of clay, which indicated that the clay most be significantly intercalated or exfoliated in the prepared nanocomposite preparation process. In addition, morphology and some of the mechanical and thermal properties of in situ PPCNs were compared with those of PPCNs prepared by melt blending method in this study and some presented reported results in literatures.
PP/clay nanocomposites: Effect of clay treatment on morphology and dynamic mechanical properties
Journal of Applied Polymer Science, 2001
The morphology and properties of polypropylene (PP)/clay nanocomposites are described. The melt intercalation of organophilic clay was carried out with a single-screw extruder. The effects of two kinds of treatments of clay are discussed. Maleic anhydride (MAH)-grafted PP was used as a compatibilizer. The expansion of the intergallery distance of the clay was governed by the interaction between the clay treatment and the compatibilizer. In one case, the composites exhibited significantly reduced intensities of diffraction peaks, suggesting partial exfoliation of the clay layers, whereas for the second clay sample, expansion of the gallery height was noted. The mechanical properties of the PP/clay composites showed significant enhancement in their mechanical and thermal properties. About a 35% increase in the tensile modulus and about a 10% increase in the tensile strength were observed. The thermal degradation temperature increased from 270 to about 400°C as a result of the incorporation of clay, and the extent depended on the dispersion of clay in the composite. The most interesting outcome of this study was the changes in morphology for PP/clay composites, which are reported here for the first time. An optical microscopic study revealed that the PP/clay composites could be crystallized at higher temperatures than pure PP and that the morphology was remarkably altered because of the presence of layers of clay. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1786–1792, 2001
Composites Science and Technology, 2012
The objective of this study was to investigate the effects of two compatibilizers, namely maleated polypropylene (PP-g-MA) and maleic anhydride grafted poly (ethylene-co-octene) (EOC-g-MA), on the morphology and thus properties of ternary nanocomposites of polypropylene (PP)/ethylene-octene copolymer (EOC)/clay nanocomposite. In this regard the nanocomposites and their neat polymer blend counterparts were processed twice using a twin screw extruder. X-ray diffraction, transmission electron microscopy, Energy dispersive X-ray spectroscopy, and scanning electron microscopy were utilized to characterize nanostructure and microstructure besides mechanical and rheological behaviors of the nanocomposites. Clay with intercalated structure was observed in EOC phase of the PP/EOC/clay nanocomposite. Better dispersion state of the intercalated clay in EOC phase was observed by adding EOCg-MA as a compatibilizer. On the other hand, adding PP-g-MA resulted in migration of the intercalated clay from the EOC to the PP and to the interface regions. It was also demonstrated that the elastomer particles became smaller in size where clay was present. The finest and the most uniform morphology was found in the PP/EOC/clay nanocomposite. In addition, the rheological results illustrated a higher complex viscosity and storage modulus for PP/EOC/PP-g-MA/clay nanocomposite in which clay particles were present in the matrix. Mechanical assessments showed improvements in the toughness of the nanocomposites with respect to their neat blends, without significant change in stiffness and tensile strength values. These results highlight a toughening role of clay in the polymer blend nanocomposites studied.
Polymer …, 2009
A sodium bentonite (montmorillonite-based layered silicate clay) was organically modified with cetyl trimethyl ammonium bromide (cetrimide), using different clay/ water ratios-but the same clay/cetrimide ratio-to suspend the bentonite clay and perform its organophilization. Infrared spectroscopy and thermogravimetric analysis indicated the incorporation of organic modifier into the bentonite. Wide-angle X-ray scattering showed that the incorporation of surfactant significantly increased the interlayer spacing in the bentonite for all concentrations studied. It was found that clay/water ratio employed during the modification affects neither the amount of organic salt incorporated nor the interlayer spacing in the organobentonites, but influences its degree of structural disorder. Lower clay/water ratios resulted in a more disorderly structure, as established by the decrease of the areas under the X-ray peaks as the clay/water ratio diminishes. The modified bentonites were melt compounded with maleic anhydride-grafted polypropylene. X-ray diffraction patterns of the hybrids revealed that the more disorderly organobentonites were better dispersed in the polymer matrix, indicating that, in the present system, the structure of polymer nanocomposites obtained were affected by the clay/water ratio used in organobentonite preparation.
Preparation and Characterization of Polypropylene/Clay Nanocomposites
Applied Mechanics and Materials, 2011
Polypropylene(PP)/clay nanocomposites were prepared by solution blending. The microstructure of PP/clay nanocomposites was studied by wide-angle X-ray diffraction (XRD) analysis. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to investigate thermal properties of PP/clay nanocomposites. XRD pattern prove that clay layers were exfoliated into nanometer size in PP matrix and that α-Phase crystallite was the main crystallite of PP in PP/clay nanocomposites. TGA examinations confirmed that the maximum decomposition temperature of PP/clay nanocomposites was higher than that of neat PP and that the thermal stability of PP/clay nanocomposites rose noticeably. Results of DSC scans showed the crystalliztion temperature of nanocomposites was slightly bigger than that of pure PP due to the efficient nucleating effects of clay layers.
Applied Clay Science, 2017
The influence of the clay mineral structure and of the polyamide dispersed phase polarity on the structure and morphology of polypropylene/polyamide blends filled with clay mineral nanoparticles was investigated. Two polyamides (PA) were used: a polar PA6 and a less polar PA12. The clay mineral nanofillers used were either organically modified montmorillonite (Mt) or synthetic talc (ST), having preferential affinity towards PA dispersed phase. For all clay polymer nanocomposites (CPN), a decrease of PA nodule size was observed. However, the mechanisms governing the morphology establishment were shown to depend mainly on the clay structure, and also on the polyamide polarity. Mt nanoparticles were shown to be mostly located at the interface, forming a nanocomposite interphase. The decrease of PA nodule size induced by Mt nanoparticles was attributed to coalescence inhibition by steric repulsions, mediated by the interphase, which is more developed in the case of PA6. Besides, the interphase was shown to play a key role in the change from a nodular to a non-nodular morphology, even at low Mt fractions. ST particles were shown to be exclusively dispersed within PA nodules. In this case, nodule size reduction was attributed to the presence of some larger ST particles, exhibiting numerous structural defects, which favor the nodule break-up, especially in the case of PA12.
Polypropylene-clay composite prepared from Indian bentonite
Bulletin of Materials Science, 2008
In the present work, a set of experimental polypropylene (PP) clay composites containing pristine bentonite clay of Indian origin has been prepared and then characterized. The polymer clay composites are processed by solution mixing of polypropylene with bentonite clay using a solvent xylene and high speed electric stirrer at a temperature around 130°C and then by compression molding at 170°C. The mechanical properties of PP-clay composites like tensile strength, hardness and impact resistance have been investigated. Microstructural studies were carried out using scanning electron microscope and transmission electron microscope and the thermal properties were studied using differential scanning calorimeter. Mechanical properties of the prepared composites showed highest reinforcing and toughening effects of the clay filler at a loading of only 5 mass % in PP matrix. Tensile strength was observed to be highest in case of 5 mass % of clay loading and it was more than 14% of that of the neat PP, while toughness increased by more than 80%. Bentonite clay-PP composite (5 mass %) also showed 60% increase in impact energy value. However, no significant change was observed in case of hardness and tensile modulus. Higher percentages of bentonite clay did not further improve the properties with respect to pristine polypropylene. The study of the microstructure of the prepared polymer layered silicate clay composites showed a mixed morphology with multiple stacks of clay layers and tactoids of different thicknesses.
IOP Conference Series: Materials Science and Engineering, 2019
Process parameters are crucial to produce targeted qualities in polypropylene (PP)/clay nanocomposites, due to their roles on the generation of shear and diffusion. Thus, this research aims to observe their effects on structures and properties of PP/clay nanocomposites. Samples were produced by mixing PP, PP grafting maleic anhydride (PP-g-MA), and Cloisite 20A at fixed compositions, 88/9/3 wt%, respectively, in an internal mixer with variations on temperatures (210, 220, 230 °C) and speeds (60, 80, 100 rpm). Effect of mixing parameters on nanocomposite structures and properties were investigated from XRD, SEM and flexural properties. The results showed that all samples had intercalated as well as agglomerated structures. Further analysis on XRD and SEM showed that samples produced at high conditions (230 °C or 100 rpm) had similar structures. In contrast, low setting sample (210 °C and 60 rpm), despite its similarity on dispersion level, had longer agglomerates than that of mixed a...
Polypropylene/clay nanocomposites: Effect of different clays and compatibilizers on their morphology
Journal of Applied Polymer Science, 2009
A set of organically modified clays (OLS) were mixed with different compatibilizers to alter their interactions with either homopolymer or heterophasic polypropylenes when they were melt-mixed, and the relation between the OLS/compatibilizer system and the composite morphology was studied. X-ray diffraction (XRD) showed that depending on the specific OLS/compatibilizer system, it is possible to obtain several morphologies in the composites. In particular, some samples prepared with compatibilizers based on itaconic acid and OLSs, which had the highest cation exchange capacity and were organically modified with a set of quaternary ammonium salts, presented longer clay interlayer distances than the original OLSs, whereas other composites showed a clay collapse associated with shorter interlayer distances. Moreover, some composites presented both kinds of morphologies together. By means of diffuse reflectance spectroscopy and thermogravimetric analysis, it was possible to show that the OLSs were stable under the operating conditions, so the decrease in the interlayer distance found in some samples was not related to degradation processes. On the other hand, high-resolution transmission electron microscopy (HR-TEM) showed that collapsed clays were formed by tactoid and immiscible structures with poor dispersion in the polymer matrix. However, samples with intercalate state from XRD presented very well dispersed multilayer stacks about 10 nm thick. Finally, those samples with both collapsed and intercalate morphologies presented tactoid and immiscible structures together with well dispersed multilayer stacks in the corresponding HR-TEM images.