Environmental ageing of irradiated polypropylene/montmorillonite nanocomposites obtained in molten state

Komatsu, Luiz Gustavo Hiroki; Oliani, Washington Luiz; Lugão, Ademar B.; Parra, D.F.

doi:10.1016/j.radphyschem.2013.12.004

Cited by 21 publications

(10 citation statements)

References 18 publications

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“…They are isomorphically replaced by Mg 2+ and Fe 2+ cations and, in addition, there are also Al 3+ cations in place of the tetrahedral silicon cations. The excess of negative charge that is created is balanced by various mono or bivalent cations (Ca 2+ , Mg 2+ , Na + , K + ) solvated and which, being unable to be inserted inside the crystal, remain located on the edges of the same, occupying the interlayer region [10][11][12]. The montmorillonite chemical formula is (Si 7.8 Al 0.2 ) IV (Al 3.4 Mg 0.6 ) VI O 20 (OH) 4 ; its composition, without considering the presence of the material between the various lamellae, is: SiO 2 (66.7%), Al 2 O 3 (28.3%), H 2 O (5%), which allows us to explain how in the montmorillonite there may be isomorphic substitutions of the Si 4+ cations with Al 3+ within the tetrahedral units, and of the Al 3+ cation with Mg 2+ in the octahedral units.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Self-Assembly Processes in Hydrated Montmorillonite by FTIR Investigations

Caccamo

Mavilia

et al. 2020

Materials

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Experimental findings obtained by FTIR and Raman spectroscopies on montmorillonite-water mixtures at three concentration values are presented. To get some insight into the hydrogen bond network of water within the montmorillonite network, FTIR and Raman spectra have been collected as a function of time and then analyzed following two complementary approaches: An analysis of the intramolecular OH stretching mode in the spectral range of 2700–3900 cm−1 in terms of two Gaussian components, and an analysis of the same OH stretching mode by wavelet cross-correlation. The FTIR and Raman investigations have been carried as a function of time for a montmorillonite-water weight composition (wt%) of 20–80%, 25–75%, and 35–65%, until the dehydrated state where the samples appear as a homogeneous rigid layer of clay. In particular, for both the FTIR and Raman spectra, the decomposition of the OH stretching band into a “closed” and an “open” contribution and the spectral wavelet analysis allow us to extract quantitative information on the time behavior of the system water content. It emerges that, the total water contribution inside the montmorillonite structure decreases as a function of time. However, the relative weight of the ordered water contribution diminishes more rapidly while the relative weight of the disordered water contribution increases, indicating that a residual water content, characterized by a highly structural disorder, rests entrapped in the montmorillonite layer structure for a longer time. From the present study, it can be inferred that the montmorillonite dehydration process promotes the layer self-assembly.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-Assembly Processes in Hydrated Montmorillonite by FTIR Investigations

Caccamo

Mavilia

et al. 2020

Materials

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“…[4][5][6] Nanoclays consist of the nanoparticles of layered mineral silicates with layered structural units that can form complex clay crystallites. [7][8][9] An individual layer unit is composed of octahedral and tetrahedral sheets. Nanocaly particle is DOI: 10.32571/ijct.430058 E-ISSN:2602-277X…”

Section: -3mentioning

confidence: 99%

Investigation of improvement of thermal and mechanical properties of polypropylene / nano clay composites

Awad¹,

Khalaf²

2018

International Journal of Chemistry and Technology

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This work aims to study the characterizations and modifications of systems based on polypropylene (PP) and nanoclay (NC). In this context, the effects of thermal and mechanical properties of the compsites of nanoclays with different loading of 1, 3, and 6% incorporated in PP matrix were investigated. The influences of thermal and mechanical properties on the preparation of polypropylene/nanoclay (PPNC) composite were investigated. The results of the thermogravimetric analysis (TGA) showed that thermal stability increased with higher loadings of nanoclay. The tensile properties of PP and PPNC were also studied. The tensile strength of PP with the higher loading of nanoclay increased by 24.40% compared to that of the pure PP matrix (27.5MPa). The modulus of elasticity of PPNC with higher loading of 6% NC was higher by 17.32% than that of pure PP. The elongation at break of PPNC reduced by 53%, by comparing with pure PP. The Tg of PNCC with higher loading of NC were higher by 8.6%. The degree of crystallinity of PPNC was higher by 27% than pure PP.

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“…Most researches focused on the changes of solid polymers before and after aging. For instance, changes of functional groups, chromophores, molecular weight, crystallinity and morphology were often used to evaluate the aging degree of polymers [8][9][10][11][12]. Some researchers turned their eyes to small molecular degradation products [13].…”

Section: Introductionmentioning

confidence: 99%

Conversion among photo-oxidative products of polypropylene in solid, liquid and gaseous states

Yang

2020

BMC Chemistry

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During aging of polymers, oxidized species on macromolecular chains in solid state, volatile degradation products in liquid state and gaseous degradation products in gaseous state are often investigated separately. The conversion among these products is not especially concerned and biased results may be obtained based on the products in a single state. In this paper, photo-oxidative products of commercial polypropylene (PP) and unstabilized PP in solid, liquid and gaseous states were investigated by using Fourier transform infrared spectroscopy (FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and gas chromatography (GC). By comparing the formation profiles, conversion among the photo-oxidative products in three states was traced. During photo-oxidative aging, the main chains of PP were first oxidized to form carbonyl species in solid state, or fractured to form volatile alkenes as liquid. With the proceeding of aging, the oxidized main chains fractured to form small molecules, resulting in the conversion of oxidized species from solid state to liquid and gaseous states. When the aging degree was extremely high, the accumulation of liquid oxidized products was limited due to migration and condensation. Therefore, both the carbonyl index (CI) and the concentrations of volatile oxidized products were increased first and then decreased, while the concentrations of gaseous products kept increasing all along.

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Environmental ageing of irradiated polypropylene/montmorillonite nanocomposites obtained in molten state

Cited by 21 publications

References 18 publications

Self-Assembly Processes in Hydrated Montmorillonite by FTIR Investigations

Self-Assembly Processes in Hydrated Montmorillonite by FTIR Investigations

Investigation of improvement of thermal and mechanical properties of polypropylene / nano clay composites

Conversion among photo-oxidative products of polypropylene in solid, liquid and gaseous states

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