Preparation and Characterization of EG-Chitosan Nanocomposites via Direct Exfoliation: A Green Methodology

Demitri, Christian; Moscatello, Anna; Giuri, Antonella; Raucci, Maria Grazia; Corcione, Carola Esposito

doi:10.3390/polym7121535

Cited by 13 publications

(9 citation statements)

References 54 publications

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“…, lower shear thinning and higher viscosities are observed at lower temperature. The obtained results show good agreement with previous studies [ 64 , 65 , 66 ].…”

Section: Resultssupporting

confidence: 92%

Correction of MHS Viscosimetric Constants upon Numerical Simulation of Temperature Induced Degradation Kinetic of Chitosan Solutions

Benedictis¹,

Soloperto²,

Demitri

2016

Polymers

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Abstract:The Mark-Houwink-Sakurada (MHS) equation allows for estimation of rheological properties, if the molecular weight is known along with good understanding of the polymer conformation. The intrinsic viscosity of a polymer solution is related to the polymer molecular weight according to the MHS equation, where the value of the constants is related to the specific solvent and its concentration. However, MHS constants do not account for other characteristics of the polymeric solutions, i.e., Deacetilation Degree (DD) when the solute is chitosan. In this paper, the degradation of chitosan in different acidic environments by thermal treatment is addressed. In particular, two different solutions are investigated (used as solvent acetic or hydrochloric acid) with different concentrations used for the preparation of chitosan solutions. The samples were treated at different temperatures (4, 30, and 80˝C) and time points (3, 6 and 24 h). Rheological, Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analyses (TGA) were performed in order to assess the degradation rate of the polymer backbones. Measured values of molecular weight have been integrated in the simulation of the batch degradation of chitosan solutions for evaluating MHS coefficients to be compared with their corresponding experimental values. Evaluating the relationship between the different parameters used in the preparation of chitosan solutions (e.g., temperature, time, acid type and concentration), and their contribution to the degradation of chitosan backbone, it is important to have a mathematical frame that could account for phenomena involved in polymer degradation that go beyond the solvent-solute combination. Therefore, the goal of the present work is to propose an integration of MHS coefficients for chitosan solutions that contemplate a deacetylation degree for chitosan systems or a more general substitution degree for polymers in which viscosity depends not only on molecular weight and solvent combinations.

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“…, lower shear thinning and higher viscosities are observed at lower temperature. The obtained results show good agreement with previous studies [ 64 , 65 , 66 ].…”

Section: Resultssupporting

confidence: 92%

Correction of MHS Viscosimetric Constants upon Numerical Simulation of Temperature Induced Degradation Kinetic of Chitosan Solutions

Benedictis¹,

Soloperto²,

Demitri

2016

Polymers

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“…The same value was found in the literature, 20 and the nanostructured nature of the expanded 'worms' is therefore confirmed. By comparing the results obtained from XRD, FESEM and BET with those present in the literature, 15,23,27,29,31 it can be concluded that the preparation of the expanded graphite (EG) filler was successfully performed.…”

Section: Resultsmentioning

confidence: 74%

“…Both diffractograms show a peak at 2y ¼ 26.16 corresponding to a d-spacing of 0.340 nm that can be attributed to the intercalation of sulfuric acid. 20,29 It is clear from these diffractograms that the NEG is mainly composed of single intercalated structures, but it also shows the coexistence of non-intercalated and intercalated layers of sulfuric acid (i.e. the flakes also contain non-intercalated graphite layers).…”

Section: Resultsmentioning

confidence: 99%

Effect of expandable and expanded graphites on the thermo-mechanical properties of polyamide 11

Oulmou

Benhamida

Dorigato

et al. 2018

Journal of Elastomers & Plastics

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The preparation and thermo-mechanical characterization of composites based on polyamide 11 (PA11) filled with various amounts of both expandable and expanded graphites are presented. Investigation conducted using X-ray diffraction (XRD), scanning electron microscopy and surface area analyses indicated how graphite expanded under the selected processing conditions. The XRD analysis on PA11/graphite composites revealed no change in the crystal form of the PA11, while the presence of diffraction peaks associated to the graphite-stacked lamellae can be still detected. All the investigated composites showed an improvement of the thermal stability and mechanical properties (elastic and storage moduli).

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“…The CS-GR composite can be easily prepared by sonication of GR and CS in acetic acid for 1 h at room temperature. Fewer reports have already reported for the preparation of CS grafted expanded GR (Jagiello et al, 2014;Demitri et al, 2015). However, for the first time we report a potential application of the GR-CS composite for the electrochemical sensing of DA.…”

Section: Introductionmentioning

confidence: 71%

Preparation of chitosan grafted graphite composite for sensitive detection of dopamine in biological samples

Palanisamy

Kokulnathan

Chen

et al. 2016

Carbohydrate Polymers

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The accurate detection of dopamine (DA) levels in biological samples such as human serum and urine are essential indicators in medical diagnostics. In this work, we describe the preparation of chitosan (CS) biopolymer grafted graphite (GR) composite for the sensitive and lower potential detection of DA in its sub micromolar levels. The composite modified electrode has been used for the detection of DA in biological samples such as human serum and urine. The GR-CS composite modified electrode shows an enhanced oxidation peak current response and low oxidation potential for the detection of DA than that of electrodes modified with bare, GR and CS discretely. Under optimum conditions, the fabricated GR-CS composite modified electrode shows the DPV response of DA in the linear response ranging from 0.03 to 20.06μM. The detection limit and sensitivity of the sensor were estimated as 0.0045μM and 6.06μA μM(-1)cm(-2), respectively.

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Preparation and Characterization of EG-Chitosan Nanocomposites via Direct Exfoliation: A Green Methodology

Cited by 13 publications

References 54 publications

Correction of MHS Viscosimetric Constants upon Numerical Simulation of Temperature Induced Degradation Kinetic of Chitosan Solutions

Correction of MHS Viscosimetric Constants upon Numerical Simulation of Temperature Induced Degradation Kinetic of Chitosan Solutions

Effect of expandable and expanded graphites on the thermo-mechanical properties of polyamide 11

Preparation of chitosan grafted graphite composite for sensitive detection of dopamine in biological samples

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