Abstract
A comparative analysis of crystallization behavior induced by several mineral fillers in polypropylene nanocomposites was performed. Morphological changes and thermal properties of nanocomposites were evaluated, considering the influence of shape, crystalline morphology, and concentration of mineral particles. For this study, hydrated magnesium silicates with different particle morphologies, such as platelets (talc) and fibers (sepiolite), were used for nanocomposites. In addition, to analyze the effect of mineral crystallinity on nanocomposites, talc and sepiolite from different origin and genesis were selected. Nanocomposites were compounded and injection molded, using different filler concentration (0, 1, and 3% w/w) for each mineral particle. To evaluate the particle influence on nanocomposite crystallinity, X-ray diffraction was used to determine crystalline phases and crystal orientation, meanwhile differential scanning calorimetry was performed to obtain thermal properties. Main results revealed that talc has a higher nucleating effect on polypropylene matrix than sepiolite fibers, regardless of their origin and genesis. Meanwhile, a transcrystalline layer that surrounds the fiber surface is observed for nanocomposite containing sepiolite. Moreover, Argentinean talc induces different crystalline phases in nanocomposite with respect to Australian one, which partly influences on mechanical properties.
Highlights
Mineral nanoparticles are widely used in polymer matrix to enhance some mechanical properties, barrier resistance, flame retardancy, and electrical and optical properties, adding only a small particle concentration.[1]
To study the influence of sepiolite and talc on PP crystallization, firstly a structural characterization of these mineral particles was performed by X-ray diffraction (XRD)
morphology index (MI) values for talc samples considered in this work are 0.83 for those containing Argentinean one (TS) and 0.45 for than Australian one (TA). These results reveal the predominant macrocrystalline morphology of TS and the microcrystalline character of TA
Summary
Mineral nanoparticles are widely used in polymer matrix to enhance some mechanical properties, barrier resistance, flame retardancy, and electrical and optical properties, adding only a small particle concentration.[1]. Microcrystalline talcs contain heterogeneous stack of small and irregular platelets, macrocrystalline ones have long, well-defined, and stacked-up platelets These morphologies determine the size of individual talc platelets which can vary from approximately 1 mm to over 100 mm.[6] new mineral phases occurred from preexisting ones during geological talc formation, which explain the presence of associated minerals in worldwide deposits. In this sense, chemical and structural parameters of talc particles are indicative of its origin and crystallization conditions. Talc ores differ in chemical composition, morphology, associated minerals, whiteness, and other properties
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