Effect of montmorillonite on the crystallization and thermal degradation of poly(propylene-co- ethylene-co-1-butene) nanocomposites

2016 ◽  
Vol 30 (6) ◽  
pp. 741-761 ◽  
Author(s):  
Verónica Riechert ◽  
Marcelo D Failla ◽  
Lidia M Quinzani
Keyword(s):  
Polymeric Nanocomposites ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
X Ray ◽  
Clay Concentration ◽  
Activation Energy Of Crystallization ◽  
Organophilic Montmorillonite ◽  
Poly Propylene ◽  
Nucleating Effect

Polymeric nanocomposites based on poly(propylene- co-ethylene- co-1-butene) (PEBC) were elaborated by melt mixing using an organophilic montmorillonite (o-MMT) and maleated PEBC (PEBCg) as compatibilizer. The effect of clay concentration, PEBCg:o-MMT ratio, and grafting degree of the compatibilizer were studied. X-ray diffraction and scanning electron microscopy show formation of partially intercalated structures in all compatibilized composites with well-distributed small tactoids. According to the differential scanning calorimetry results, the anhydride groups of the compatibilizer have a marginal nucleating effect, while the o-MMT causes a slight decrease in the crystallization temperature of the polymer. PEBC presents the largest activation energy of crystallization ( Eα), while the composites show lower Eα than their matrices. It is also observed that the rate of degradation of PEBC is not affected by the presence of PEBCg. The nanoclay, on the other hand, retards the decomposition process of the polymeric matrix in about 40°C and augments its rate of degradation approximately four times.

Study of Morphology Membrane of Polymeric Nanocomposites Obtained by Phases Inversion

2014 ◽  
Vol 775-776 ◽  
pp. 498-503 ◽  
Author(s):  
Keila Machado Medeiros ◽  
Taciana Regina de Gouveia Silva ◽  
Dayanne Diniz Souza Morais ◽  
Luana Rodrigues Kojuch ◽  
Edcleide Maria Araújo ◽  
...  
Keyword(s):  
Polymer Nanocomposites ◽  
Phase Inversion ◽  
Structural Modification ◽  
Bentonite Clay ◽  
Polymeric Nanocomposites ◽  
X Ray Diffraction ◽  
Nanocomposite Membranes ◽  
Scanning Calorimetry ◽  
Selective Layer ◽  
X Ray

In this work, were obtained nanocomposite membranes polyamide66/Paraíba bentonite clay, treated with a quaternary ammonium salt in order to make it organophilic. The membranes were prepared as thin films using the technique of phase inversion from the nanocomposites obtained by solution. The membranes were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM). By means of X-ray diffractogram, it was revealed that the membranes remained organically treated clay presented exfoliated and/or partially exfoliated structure. From curves of DSC and TG, it was observed that membrane of PA66 with 3% w/w of with treatment clay showed higher thermal stability compared with the same content of clay without treatment. From the SEM photomicrographs, there was a selective layer (skin filter) on top and one porous layer at the bottom of all membranes studied. Moreover, it was verified that the presence of clay provided a significant structural modification in the membranes of polymer nanocomposites.

scholarly journals Surface Modification of Sodium Montmorillonite Nanoclay by Plasma Polymerization and Its Effect on the Properties of Polystyrene Nanocomposites

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Rosa Idalia Narro-Céspedes ◽  
María Guadalupe Neira-Velázquez ◽  
Luis Fernando Mora-Cortes ◽  
Ernesto Hernández-Hernández ◽  
Adali Oliva Castañeda-Facio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Plasma Polymerization ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Sodium Montmorillonite ◽  
X Ray ◽  
Montmorillonite Nanoclay ◽  
Scanning Electron

Sodium montmorillonite nanoclay (Na+-MMT) was modified by plasma polymerization with methyl methacrylate (MMA) and styrene (St) as monomers and was denominated as Na+-MMT/MMA and Na+-MMT/St, respectively. This plasma modified nanoclay was used as reinforcement for polystyrene (PS) nanocomposites that were prepared by melt mixing. Pristine and modified Na+-MMT nanoclay were analyzed by the dispersion in various solvents, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results confirmed a change in hydrophilicity of the modified Na+-MMT, as well as the presence of a polymeric material over its surface. The pristine PS/Na+-MMT and modified PS/Na+-MMT/MMA and PS/Na+-MMT/St nanocomposites were studied with X-ray diffraction (XRD), differential scanning calorimetry (DSC), and TGA, as well as mechanical properties. It was found that the PS/Na+-MMT/St nanocomposites presented better thermal properties and an improvement in Young’s modulus (YM) in compared to PS/Na+-MMT/MMA nanocomposites.

scholarly journals Effect of Mg contents on the mechanical proprieties and precipitation kinetics in Al–3.3 wt.% Cu alloy

2018 ◽  
Vol 23 (4) ◽  
pp. 335-345
Author(s):  
Messaoud Fatmi ◽  
A. Ouali ◽  
Amar Djemli ◽  
Tayeb Chihi ◽  
M A Ghebouli ◽  
...  
Keyword(s):  
Discontinuous Precipitation ◽  
Precipitation Reaction ◽  
Precipitation Kinetics ◽  
Transformation Kinetics ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Cu Alloy ◽  
Discontinuous Precipitation Reaction ◽  
Activation Energy Of Crystallization

The effect of additional Mg on the microstructure, mechanical properties, and transformation kinetics during aging in Al–3.3 wt.% Cu alloy was studied. The compositions and microstructure were examined by X-ray diffraction, Differential scanning calorimetry (DSC) and scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The results show that the Mg in the Al–Cu alloy mainly precipitated to the grain boundaries during the process of transformation and formed a ternary Al2CuMg metallic compound and the rate of discontinuous precipitation reaction decreases with increasing concentration of Mg. The activation energy of crystallization was evaluated by applying the Kissinger equation.

Studies on the Preparation, Characterization and Solubility of -Cyclodextrin-Roxythromycin Inclusion Complexes

2009 ◽  
Vol 2 (2) ◽  
pp. 523-530
Author(s):  
D. Nagasamy Venkatesh ◽  
S. Karthick ◽  
M. Umesh ◽  
G. Vivek ◽  
R.M. Valliappan ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Inclusion Complexes ◽  
Phase Solubility ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ir Studies ◽  
Poorly Soluble ◽  
Poorly Soluble Drug

Roxythromycin/ β-cyclodextrin (Roxy/ β-CD) dispersions were prepared with a view to study the influence of β-CD on the solubility and dissolution rate of this poorly soluble drug. Phase-solubility profile indicated that the solubility of roxythromycin was significantly increased in the presence of β-cyclodextrin and was classified as AL-type, indicating the 1:1 stoichiometric inclusion complexes. Physical characterization of the prepared systems was carried out by differential scanning calorimetry (DSC), X-ray diffraction studies (XRD) and IR studies. Solid state characterization of the drug β-CD binary system using XRD, FTIR and DSC revealed distinct loss of drug crystallinity in the formulation, ostensibly accounting for enhancement of dissolution rate.

scholarly journals A review of nanotechnology with an emphasis on Nanoplex

2015 ◽  
Vol 51 (2) ◽  
pp. 255-263
Author(s):  
Rupali Nanasaheb Kadam ◽  
Raosaheb Sopanrao Shendge ◽  
Vishal Vijay Pande
Keyword(s):  
Drug Delivery ◽  
Drug Delivery Systems ◽  
Drug Loading ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Conventional Drug ◽  
Anionic Drugs ◽  
Oppositely Charged ◽  
The Brain

<p>The use of nanotechnology based on the development and fabrication of nanostructures is one approach that has been employed to overcome the challenges involved with conventional drug delivery systems. Formulating Nanoplex is the new trend in nanotechnology. A nanoplex is a complex formed by a drug nanoparticle with an oppositely charged polyelectrolyte. Both cationic and anionic drugs form complexes with oppositely charged polyelectrolytes. Compared with other nanostructures, the yield of Nanoplex is greater and the complexation efficiency is better. Nanoplex are also easier to prepare. Nanoplex formulation is characterized through the production yield, complexation efficiency, drug loading, particle size and zeta potential using scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and dialysis studies. Nanoplex have wide-ranging applications in different fields such as cancer therapy, gene drug delivery, drug delivery to the brain and protein and peptide drug delivery.</p>

scholarly journals Diethylstilbestrol Modifies the Structure of Model Membranes and Is Localized Close to the First Carbons of the Fatty Acyl Chains

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 220
Author(s):  
Alessio Ausili ◽  
Inés Rodríguez-González ◽  
Alejandro Torrecillas ◽  
José A. Teruel ◽  
Juan C. Gómez-Fernández
Keyword(s):  
Membrane Surface ◽  
Water Layer ◽  
Fatty Acyl ◽  
31P Nmr Spectroscopy ◽  
Relaxation Rates ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Acyl Chains ◽  
Dynamics Simulations

The synthetic estrogen diethylstilbestrol (DES) is used to treat metastatic carcinomas and prostate cancer. We studied its interaction with membranes and its localization to understand its mechanism of action and side-effects. We used differential scanning calorimetry (DSC) showing that DES fluidized the membrane and has poor solubility in DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) in the fluid state. Using small-angle X-ray diffraction (SAXD), it was observed that DES increased the thickness of the water layer between phospholipid membranes, indicating effects on the membrane surface. DSC, X-ray diffraction, and 31P-NMR spectroscopy were used to study the effect of DES on the Lα-to-HII phase transition, and it was observed that negative curvature of the membrane is promoted by DES, and this effect may be significant to understand its action on membrane enzymes. Using the 1H-NOESY-NMR-MAS technique, cross-relaxation rates for different protons of DES with POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) protons were calculated, suggesting that the most likely location of DES in the membrane is with the main axis parallel to the surface and close to the first carbons of the fatty acyl chains of POPC. Molecular dynamics simulations were in close agreements with the experimental results regarding the location of DES in phospholipids bilayers.

scholarly journals Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zaiqiang Feng ◽  
Mingqi Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Velocity ◽  
Sintered Density ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
High Velocity Compaction ◽  
Sintered Temperature

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

scholarly journals Extraction of Boron from Ludwigite Ore: Mechanism of Soda-Ash Roasting of Lizardite and Szaibelyite

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 533 ◽  
Author(s):  
Xin Zhang ◽  
Guanghui Li ◽  
Jinxiang You ◽  
Jian Wang ◽  
Jun Luo ◽  
...  
Keyword(s):  
Sodium Carbonate ◽  
Energy Dispersive Spectrometer ◽  
Low Grade ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selective Activation ◽  
X Ray ◽  
Shed Light ◽  
Soda Ash ◽  
Scanning Electron

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, lizardite and szaibelyite were prepared and their soda-ash roasting behaviors were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analyses, in order to shed light on the soda-ash activation of boron within ludwigite ore. Thermodynamics of Na2CO3-MgSiO3-Mg2SiO4-Mg2B2O5 via FactSage show that the formation of Na2MgSiO4 was preferential for the reaction between Na2CO3 and MgSiO3/Mg2SiO4. While, regarding the reaction between Na2CO3 and Mg2B2O5, the formation of NaBO2 was foremost. Raising temperature was beneficial for the soda-ash roasting of lizardite and szaibelyite. At a temperature lower than the melting of sodium carbonate (851 °C), the soda-ash roasting of szaibelyite was faster than that of lizardite. Moreover, the melting of sodium carbonate accelerated the reaction between lizardite with sodium carbonate.

scholarly journals Mechanochemical treatment of Serbian kaolin clay to obtain high reactive pozzolana

2013 ◽  
Vol 78 (4) ◽  
pp. 579-590 ◽  
Author(s):  
Aleksandra Mitrovic ◽  
Miodrag Zdujic
Keyword(s):  
Hardened Steel ◽  
Pozzolanic Activity ◽  
Mechanochemical Treatment ◽  
Kaolin Clay ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Milling Parameters ◽  
Milling Medium ◽  
The Given

Mechanochemical treatment of Serbian kaolin clay was carried out in a planetary ball mill using two different milling media, hardened steel or zirconia vials and balls. The samples obtained with various milling times were characterized by the particle size laser diffraction (PSLD), X-ray diffraction (XRD), differential scanning calorimetry/thermogravimetry (DTA/TGA) and Fourier-transform infrared (FTIR) analyses. Mechanochemical treatment induced amorphization of the kaolinite phase accompanied by dehydroxylation. It was found that for the given milling parameters, amorphization mainly took place in the milling period up to 15 min, and was completed after about 30 min of milling for both milling media used. The pozzolanic activities were determined by the Chapelle method. Milling in the hardened steel milling medium had no significant influence on pozzolanic activity, even though there was accumulated iron contamination. For both milling media, pozzolanic activity of 0.79 was obtained for the samples milled for 15 min and it remained almost unchanged with prolonged milling. The determined pozzolanic activity values are close to these of commercial metakaolinite or metakaolinite obtained by the calcination of the same clay, therefore, indicating possibility for obtaining high reactive pozzolana by mechanochemical treatment of Serbian kaoline clay.

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