Organo-modified Montmorillonite Research Articles

Structure and Mechanical Properties of iPP-Based Nanocomposites Crystallized under High Pressure.

The unique nonparallel chain arrangement in the orthorhombic γ-form lamellae of isotactic polypropylene (iPP) results in the enhancement of the mechanical properties of γ-iPP. Our study aimed at the investigation of the mechanical properties of γ-iPP nanocomposites with 1-5 wt.% multiwall carbon nanotubes (MWCNT) and 5 wt.% organo-modified montmorillonite prepared by melt-mixing and high-pressure crystallization. Neat iPP and the nanocomposites were crystallized under high pressures of 200 MPa and 300 MPa, and for comparison under 1.4 MPa, in a custom-built high-pressure cell. The structure of the materials was studied using WAXS, SAXS, DSC, and SEM, whereas their mechanical properties were tested in plane-strain compression. Under a small pressure of 1.4 MPa, polymer matrix in all materials crystallized predominantly in the α-form, the most common monoclinic form of iPP, whereas under high pressure it crystallized in the γ-form. This caused a significant increase in the elastic modulus, yield stress, and stress at break. Moreover, due to the presence of MWCNT, these parameters of the nanocomposites exceeded those of the neat polymer. As a result, a 60-70% increase in the elastic modulus, yield stress, and stress at break was achieved by filling of iPP with MWCNT and high-pressure crystallization.

Montmorillonite Exfoliation in LLDPE and Factors Affecting Its Orientation: From Monolayer to Multi-Nano-Layer Polymer Films.

The motivations of the present work are to investigate the exfoliation of montmorillonite within a linear low-density polyethylene matrix and to control its orientation during the cast extrusion process. The first part is focused on the exfoliation of the montmorillonite through the melt extrusion process. The accuracy and relevance of each method used to determine the exfoliation state of montmorillonite have been examined, thanks to X-ray diffraction, transmission electronic microscopy, and rheology. All these methods have presented limitations, but the combination of all leads to a better estimation of the exfoliation state. Finally, the orientation of the montmorillonite is quantified systematically by X-ray texture analysis and correlated with process parameters to discern which one is affecting their orientation. The results have demonstrated an enhancement of the "in-plane" orientation of the montmorillonite with the exfoliation, especially at high concentration and when combined with cast extrusion. Finally, in the multi-nano-layer polymer film configuration, the reduction of the individual layers 29 nm thickness leads to some orientation improvements. However, these improvements are almost at the same level as the concentration effect in a monolayer system. This work gives an overview of all the parameters needed to achieve a significant organo-modified montmorillonite "in-plane" orientation.

PREPARATION AND FLAME RETARDANT APPLICATION OF CLAY POLYURETHANE NANOCOMPOSITES

In recent years, clay-based organic thermosetting polyurethane polymer nanocomposites have more attracted attention in academia and industries because they exhibit different properties from conventional materials. In this study, we investigated novel thermoplastic Polyurethane (TPU) by adding nanoparticles of clay as a fire-retardant property. By employing an in-situ polymerization technique with a 2:1 ratio of tolylene 2,4-diisocyanate (TPI) and polyethylene glycol (PEG2000), the NCO terminated TPU prepolymer was created. Cloisite 25A (C25A), an organo-modified montmorillonite clay, was utilized to provide sufficient compatibility with the PEG/TPI matrix. The synthesized nanocomposite was examined using thermogravimetric analysis (TGA), SEM analysis, and X-ray diffraction (XRD). FTIR analysis provides information on functional groups. Compared to pure polyurethane, the nanocomposites showed superior thermal stabilities, as determined by thermogravimetric analysis (TGA). The results from X-ray diffraction and Scanning Electron Microscopy confirm the successful formation of an exfoliated polymer clay nanocomposite under all conditions, evidenced by the absence of the distinct peak (2θ = 4.79º) corresponding to the d-spacing of the organoclay. The relationship between clay loading and TPU matrix type and the mechanical characteristics of nanocomposites was examined. As the amount of clay in the Young's TPU/Cl25A nanocomposites grew, so did their tensile strength and modulus. The fire-retardant experiment was studied by a cone colorimeter. There have been notable advancements in the fire-retardant qualities, including smoke, CO output, and heat release rate. Comparing polyurethane integrated with 5-weight percent organoclay to ordinary polyurethane polymer, a noteworthy 53% reduction was observed.

Effect of low-pressure plasma treatment on the thermal behaviour of organo-modified montmorillonite nanoclay

The thermal behaviour of nanoclay can be considered an important factor in obtaining high-performance polymer nanocomposite. Thus, the current study aims to investigate the effect of plasma treatment on the thermal stability of two organically modified nanoclays, Cloisite 30B (C30B) and Nanomer I.34TCN (I.34TCN), compared with pristine NaMMT.The nanoclays were studied and characterised using Thermogravimetric Analysis (TGA). TGA was used to measure the weight loss of the plasma-treated and untreated nanoclays (C30B, I.34TCN, and NaMMT nanoclays) over a 30-630 C temperature range.Based on TGA results, the decomposition of all plasma-treated nano clays (C30B, I.34TCN and pristine NaMMT) was shifted to a lower temperature than in the untreated ones at all those stages. Thus, plasma treatment was successfully used as a convenient method to alter the chemical structure and surface morphology of MMT nanoclays for better thermal behaviour and filling distribution.This hypothesis can be corroborated by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) for a better understanding of the structural and surface changes that occurred due to the plasma action, which can provide an interpretation of the changes in the thermal behaviour of nanoclays.The plasma treatment, therefore, can improve the thermal stabilisation of the nanocomposite powders for the LS fabricated parts and even for the surrounding powder for the recovery process. Plasma-treated nano clay, therefore, can be used to reinforce polymers with an expectation of increasing the thermal stability of the resultant composites. Thus, the plasma-treated composite can be fabricated for laser sintering applications in fields that require high thermal stability.The surface modification of nanoclay powders via plasma treatment can be used as a convenient method to alter the chemical structure and surface morphology for better thermal behaviour and filling distribution.

Multinanolayered PA6/Cloisite and PE/PA6/Cloisite composites: Structure, mechanical and barrier properties

Economic and environmental challenges are driving development towards more efficient and lighter materials. Polyethylene (PE) and polyamide (PA6) are among the most used polymers and their assembly in multilayer make them efficient protective materials. The aim of this work is to design new multilayer composite films based on polyethylene and polyamide with high barrier properties. A coextrusion process with layer multiplier elements (LME) made it possible to carry out 100 μm-thick multilayer films containing 5 up to 1025 layers. Loaded PE/PA6 multilayer films were made by incorporating Cloisite particles (organo-modified montmorillonite – C30B) at 5 wt% into the PA6 layers. For comparison PA6 films with and without fillers were also made by using the same coextrusion process. The structural and thermal properties of all multilayer films were correlated with the water and gas barrier properties. A good dispersion of exfoliated C30B in the PA6 phase was observed even for the thinnest confined layers of PA6 in PE/PA6 multilayers (∼90 nm). We showed the complexity of the multinanolayer structures involving interphases as well as the complexity of the transfer mechanisms. The serial model used for predicting permeability highlighted some significant improvements of the gas barrier properties of confined PA6 layers. The barrier effect on all the multilayer films was, however, limited due to the “on-edge” orientation of the crystalline phases and structural defects induced during the coextrusion process. Despite this, the confinement of nanofillers in PA6 multilayers and in PA6 layers of PE/PA6 multilayers allowed to increase the barrier properties of multilayers.

Time- and temperature-dependent mechanical and rheological behaviours of injection moulded biodegradable organoclay nanocomposites

Injection moulded specimens were produced from biodegradable poly(butylene succinate) (PBS)/organomodified montmorillonite (OMMT) nanocomposites, after melt compounding in different compositions. WAXD studies demonstrated that the OMMT formed similar intercalation levels in the 2.5–10 w/w% additive ratio range. It was also proved by rotational rheometry that the nanoclay stacks form physical network above 5 w/w% concentration, which significantly influence the viscoelastic properties of the melt. The value of zero shear viscosity also changed accordingly, starting to increase above 5 w/w% nanoclay content. The OMMT content reduced the creep sensitivity measured in molten state.X-ray and DSC investigations showed that OMMT inhibits the crystallisation of PBS, resulting in a decrease in crystallinity at higher nanoclay ratios. As a result, the room temperature creep increased with the OMMT ratio.The Young's modulus linearly increases in the entire concentration range exceeding 1.2 GPa at 10 w/w% nanoclay content. The value of yield strength does not change significantly (35–40 MPa), but the strain at yield – which characterises stiffness – and the notched Izod impact strength already decrease at 2.5 w/w% OMMT content, but further increasing the nanoclay content has minor effect. However, the nanocomposite with 10 w/w% OMMT can be a real alternative to polypropylene (PP) and high-density polyethylene (HDPE) injection moulded products based on its mechanical properties.To characterise the effect of OMMT on dynamic mechanical properties, the S (Stiffening effectiveness), L (Loss effectiveness) and D (Damping effectiveness) indices were introduced to quantitatively describe the nanoclay effect intensity in each temperature range.

Polymer-silicate composites based on ultra-high molecular weight polyethylene and organo-modified montmorillonite

In this paper, the influence of organo-modified montmorillonite (oMMT) on the properties and structure of ultra-high molecular weight polyethylene (UHMWPE) are studied. The technology of preliminary mechanical activation of oMMT in a planetary mill was proposed. The structure and morphology of oMMT before and after mechanical activation in a planetary mill were investigated using scanning electron microscopy and IR spectroscopy. It was found that preliminary mechanical activation leads to dispersion and increase in the porosity of oMMT. Heat treatment at the temperature of the composite material processing does not lead to the destruction of organic modifiers. Studies of the mechanical properties of polymer-silicate composites have revealed that the introduction of preliminary mechanically activated oMMT contributes to the increase of tensile and compressive strength of the composite material based on ultra-high molecular weight polyethylene.

UV-cured gel polymer electrolytes based on poly (ethylene glycol) and organo-modified nanoclays for lithium ions batteries

Next-generation electrolytes for Lithium Ion Batteries (LIBs) must provide increased durability, reliability, safety, and scalability to meet the even more stringent technical requirements of crucial industries such as e-mobility. A promising strategy to merge these technical needs is the development of easy-to-prepare gel polymer electrolytes (GPEs) able to ensure satisfactory conductivity, high stability, and reduced flammability. In this study, we propose the preparation of novel nanocomposite GPEs through one-pot in-situ photo-polymerization (UV-curing), which turns out to be of great interest due to its low-cost, solvent-free and energy-saving characteristics. Poly (ethylene glycol) dimethacrylate (PEG-DMA) was used as hosting polymer matrix, while 1 M Lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) in ethylene carbonate/dimethyl carbonate (EC/DMC) was used as electrolyte solution. Organo-modified montmorillonite (fMt, intercalated with CTAB) was synthesized and tested as a nanofiller. Both materials and GPEs were characterized by a combination of experimental techniques including FTIR, XRD, SEM, and DMA. Noteworthy, a thorough and systematic study of the lithium-ion transport properties in the prepared GPEs was carried out using pulsed-field gradient nuclear magnetic resonance (PFG-NMR) and electrochemical impedance spectroscopy (EIS). This preliminary study demonstrated the gP-fMt combines ease of preparation and excellent safety (i.e., thermomechanical stability up to 250 °C and nonflammability) with satisfactory lithium transport properties.

Composition controllable multifunctionality of PVDF/PMMA/BaTiO3/OMMT based ternary and quaternary hybrid polymer nanocomposites

State-of-the-art engineered multifunctional nanocomposites composed of different polymer matrices and functional nanomaterials are in high industrial demand for advances in all-solid-state flexible device technologies. Within this framework, the host matrices of poly(vinylidene fluoride) (PVDF) and its blend with poly(methyl methacrylate) (PMMA), and the barium titanate (BaTiO3) and organo-modified montmorillonite (OMMT) clay mixed nanomaterial dispersed ternary PVDF/x wt% (BaTiO3+OMMT) and quaternary (PVDF+PMMA)/x wt% (BaTiO3+OMMT) hybrid polymer nanocomposites (HPNCs) are prepared through ultrasonicated homogenized solution casting method. The XRD patterns and FTIR transmittance spectra confirmed the composition dependent crystal phases of the PVDF and the heterogeneous polymer-polymer and polymer-nanomaterial interactions in these HPNC materials. The DSC measurements explained a huge alteration in the PVDF crystallite melting temperatures and also the degree of crystallinity of different HPNC materials. The UV–Vis absorbance of these hybrid materials depends strongly on their composition design and demonstrated dual energy band gaps attributed to host polymer matrices and the nanofillers. The dielectric permittivity dispersion in the broadband frequency range of 20 Hz − 1 GHz explains the contribution of several polarizations and relaxation processes in these complex composites, at 27 °C. Appreciably high dielectric permittivity (4 to 7) in the 20 Hz − 1 MHz range and low permittivity at the ultra high radio frequencies confirmed the promising nanodielectric characteristics of these hybrid materials. The interesting structure-property relationship, tunable energy band gaps, a wide range of composition controllable dielectric permittivity, and frequency dependent electrical conductivity revealed the usefulness of these HPNCs in making flexible-type innovative optoelectronic, capacitive energy storage, and microelectronic devices.

Optical characterization of PVDF/PMMA/OMMT hybrid polymer nanocomposite films for futuristic optoelectronic devices

Hybrid polymer nanocomposite (HPNC) films based on poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend (80/20 wt/wt%) host matrix and organo-modified montmorillonite (OMMT) nanoclay filler (concentrations 0.0, 2.5, 5.0, and 10 wt%) are prepared by the homogenized solution casting method. The X-ray diffraction (XRD) and scanning electron microscopic (SEM) studies revealed the formation of intercalated and exfoliated OMMT structures in the prepared composites. The detailed optical characterization of these HPNC films is carried out with measurements of absorbance spectra by employing a dual beam ultraviolet-visible (UV-Vis) spectrophotometer of wavelength range 200–800 nm. The varying amounts of dispersed OMMT into the PVDF/PMMA blend matrix leads to a gradual decrease in the direct energy band gap of the host matrix from 5.12 eV to 4.54 eV and also shows semiconductive characteristics of 3.83 eV wide band gap at higher nanofiller concentrations. The band gap values of these HPNC films are compared and discussed with other composites of different polymer blend matrices dispersed with a variety of nanofillers. The increase of OMMT concentrations enhanced the range of refractive index (1.85–2.65), extinction coefficient (1.14–10.69 × 10–4), optical range dielectric permittivity (3.44–7.07), and optical conductivity (1.32–17.14 × 1011 s−1) of these HPNC films, at a fixed wavelength of 500 nm, which further changes largely with the alteration in wavelength of incident photons. The nanofiller concentration controllable optical parameters of these PVDF/PMMA/OMMT based HPNCs reveal that they could be promising performance and multipurpose optical materials in the advances of futuristic flexible-type optoelectronic devices.

Broadband dielectric behaviour and structural characterization of PVDF/PMMA/OMMT polymer nanocomposites for promising performance nanodielectrics in flexible technology advances

Characterization of broadband dielectric behaviour of polymer nanocomposites (PNCs) is vital for the exploration of efficient nanodielectrics as energy storage, flexible dielectric substrates, and insulators in a wide range of advanced electronic device technologies. Accordingly, herein, PNC films based on poly(vinylidene fluoride) (PVDF)/ poly(methyl methacrylate) (PMMA) blend matrix (80/20 wt/wt%) dispersed with 0, 2.5, 5, and 10 wt% organo-modified montmorillonite (OMMT) nanoclay are developed by state-of-the-art homogenized solution casting method. These PVDF/PMMA/OMMT compositions based flexible PNC films are characterized in detail by employing a scanning electron microscope (SEM) equipped with energy dispersive x-ray (EDX) device, x-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectrometer, differential scanning calorimeter (DSC), inductance-capacitance-resistance (LCR) meter, and impedance/material analyzer (IMA). The SEM microimages, XRD traces, and FTIR spectra evidenced appreciable homogeneity and surface morphology, intercalated and exfoliated OMMT structures, and the α, β and γ-phase crystallites of the PVDF in these complex semicrystalline PNCs. The DSC thermograms confirmed a significant alteration in the melting temperature and degree of crystallinity of the PVDF crystallites with the increased amount of OMMT in the 80PVDF/20PMMA blend host matrix. The broadband dielectric dispersion spectra over the frequency range of 20 Hz−1 GHz explained the contribution of interfacial polarization in the complex dielectric permittivity at lower experimental frequencies, whereas at higher frequencies permittivity is ruled by dipolar polarization in these composites at 27 °C. The dielectric loss angle tangent and electric modulus spectra revealed an intense structural dynamics relaxation process in the upper radio frequency region. The influence of OMMT concentration on the dielectric permittivity and electrical conductivity is explored. The detailed dielectric and electrical characterization of these innovative semicrystalline composites with important structural and thermal properties revealed their immense potential as high-performance nanodielectrics for highlighting current applications of broadband frequency range electrical and electronic device technologies.

Designing Antioxidant and Antimicrobial Polyethylene Films with Bioactive Compounds/Clay Nanohybrids for Potential Packaging Applications

In the present work, direct incorporation of bioactive compounds onto the surface and interlayer of nanoclays before their incorporation into the final polymeric film was conducted, based on a green methodology developed by our group that is compatible with food packaging. This will lead to the higher thermal stability and the significant reduction of the loss of activity of the active ingredients during packaging configuration. On this basis, the essential oil (EO) components carvacrol (C), thymol (T) as well as olive leaf extract (OLE), which is used for the first time, were incorporated onto organo-modified montmorillonite (O) or inorganic bentonite (B) through the evaporation/adsorption method. The prepared bioactive nanocarriers were further mixed with low-density polyethylene (LDPE), via melt compounding, in order to prepare films for potential use as fresh fruit and vegetable packaging material. Characterization of the bioactive nanocarriers and films were performed through XRD, TGA, tensile, antimicrobial and antioxidant tests. Films with organically modified montmorillonite loaded with carvacrol (OC), thymol (OT) and olive leaf extract (OOLE) at 5% wt. showed better results in terms of mechanical properties. The films with polyethylene and organically modified montmorillonite loaded with carvacrol or thymol at 20% wt. (PE_OC20 and PE_OT20), as well as with olive leaf extract at 5 or 10 %wt., clay:bioactive substance ratio 1:0.5 and 10% compatibilizer (PE_OOLE5_MA10 and PE_OOLE10_MA10) exhibited the highest antioxidant activity. The resulting films displayed outstanding antimicrobial properties against Gram-negative Escherichia coli (E. coli) with the best results appearing in the films with 10% OC and OT.

Bitumen improvement with bio-oil and natural or organomodified montmorillonite: Structure, rheology, and adhesion of composite asphalt binders

The use of nanoscale particles and modifiers from renewable raw materials are modern approaches to improving the properties of existing materials. This paper examines the combined application of montmorillonite nanoparticles (10–30%) and bio-oil (5–20%) to improve the properties of bitumen binder. A study of the rheological and wetting properties of bitumen has shown that the addition of 10% bio-oil alone maximizes the adhesion of bitumen to silicate surface without a noticeable deterioration in the fluidity of its melt. Due to bitumen’s hydrophobicity and bio-oil’s hydrophilicity, montmorillonite was considered in two variants: hydrophilic (natural) and hydrophobic (organomodified). Hydrophilic particles form submillimeter aggregates in the bitumen medium, reduce its viscosity at low content and high temperatures, and shift the solid–liquid transition point towards lower temperatures. In addition, these particles increase the bitumen’s stiffness upon cooling, its cohesion and adhesion, but slightly worsen the low-frequency elasticity. Hydrophobic clay affects the bitumen’s properties more strongly, which is due to its exfoliation to nanoscale particles. This clay causes the gelling of bitumen binder at high concentrations over a wide temperature range, significantly improving its elasticity, stiffness, cohesion, and adhesion. Hydrophobic particles are better suited to produce a high-quality binder but make it highly viscous.

Absorption Performances of PLA-Montmorillonite Nanocomposites Thin Films in Salisbury and Rozanov Configurations: Influence of Aging and Mechanical Recycling.

The present paper aims to address the crucial concern of pollution induced by growing plastic waste and electromagnetic interference (EMI). Nanocomposites combining poly(lactic acid) (PLA) and organo-modified montmorillonite (OMMT) are synthesized and compression molded into thin films. A first set of samples, referred as virgin, was kept as is, while a second set of samples were photochemically, thermally and hydrolytically aged before mechanical recycling via extruding and second compression molding, resulting in the so-called recycled composite. The electromagnetic (EM) properties with a focus on microwave absorption performances of virgin and recycled samples are compared for various thicknesses and weight concentrations of OMMT in PLA matrix. The EM performances are gauges by Rozanov and Salisbury structures that consist in one- and two-layer stacks of composite films back-coated by a metal foil. Characterization in Rozanov configuration shows an average absorption index over the Ka band of 29.3% and 21.1% for, respectively, virgin and recycled PLA reinforced with 4 wt.% OMMT. An optimization of the film thickness is proposed; up to 61.85% and 80% of absorption with a thickness of 1.4 mm and 3.75 mm, respectively, is reached with a metal back-coated rPLA-4%OMMT film. Characterization in Salisbury configuration gives advantage to the recycled structure with an average absorption of 49.6% for a total thickness of 1.4 mm. The requirements of EMI shielding are met by PLA-OMMT composites with a certain benefit of recycling process on EM performance.

Active and pH-Sensitive Nanopackaging Based on Polymeric Anthocyanin/Natural or Organo-Modified Montmorillonite Blends: Characterization and Assessment of Cytotoxicity.

Polymeric anthocyanins are biologically active, pH-sensitive natural compounds and pigments with beneficial functional, pharmacological and therapeutic properties for consumer health. More recently, they have been used for the manufacture of active and pH-sensitive ("intelligent") food nanopackaging, due to their bathochromic effect. Nevertheless, in order for polymeric anthocyanins to be included either as a functional food or as a pharmacological additive (medicinal food), they inevitably need to be stabilized, as they are highly susceptible to environmental conditions. In this regard, nanopackaging has become a tool to overcome the limitations of polymeric anthocyanins. The objective of this study was to evaluate their structural, thermal, morphological, physicochemical, antioxidant and antimicrobial properties, as well as their responses to pH changes, and the cytotoxicity of blends made from polymeric anthocyanins extracted from Jamaica flowers (Hibiscus sabdariffa) and natural or organo-modified montmorillonite (Mt), as active and pH-sensitive nanopackaging. This study allowed us to conclude that organo-modified Mts are efficient pH-sensitive and antioxidant nanopackaging systems that contain and stabilize polymeric anthocyanins compared to natural Mt nanopackaging and stabilizing polymeric anthocyanins. However, the use of these polymeric anthocyanin-stabilizing organo-modified Mt-based nanopackaging systems are limited for food applications by their toxicity.

Investigation of self-healing properties of nanoclay-modified asphalt binder using two-piece healing test

Asphalt's self-healing properties demonstrate the capability to partially or even fully restore the damage caused by external loads, which could be improved using innovative modifying materials. In this study, the impact of nanoclays on asphalt performance grading (PG), complex shear modulus, and self-healing properties are investigated on a laboratory scale. The intrinsic healing phenomenon of the analyzed binders is measured using a two-piece healing test. Prepared by high shear mixing, the modified binders containing different dosages of two types of organo-modified montmorillonites were evaluated in this paper. In addition to the Superpave PG, the dispersion method's effectiveness was analyzed using a scanning electron microscope. This study indicates that nanoclays improve the high-temperature performance grade of the binder, while they do not hinder the low-temperature performance. Finally, nanoclay-modified binders showed higher shear strength and improved self-healing properties compared to the unmodified binder.

Bio-films based on alginate/modified clay through spray drying: Mechanical, rheological, morphological, and transport properties for potential use as active food packaging

In this study, encapsulated modified montmorillonite with alginate (MMT-TBZC16/Alg) content and its incorporation into the biopolymer on morphological, mechanical, rheological, and transport properties of bio-based films based on chitosan were analyzed. The spray-drying approach was used to create organo-modified montmorillonite with alginate as a biopolymer. These encapsulating materials were then described and used as reinforcing agents for chitosan in the second step of this investigation to produce new reinforced biofilms with improved performance. This study aimed to study the effect of the addition of encapsulated organo-montmorillonite into the chitosan solution on the mechanical, rheological, and transport properties of the elaborated films. Films reinforced with encapsulated modified montmorillonite were characterized using Fourier transform infrared spectroscopy (FTIR), Water vapor transmission rate (WVTR) as well as mechanical and rheological properties. Adding encapsulated reinforcing agents to chitosan-based films is an option for improving mechanical and water barrier qualities. These results suggest that the developed MMT-TBZC16/Alginate-based chitosan films with higher performances could be used in designing potential packaging films.

Effect of adding organo-modified montmorillonite nanoclay on the performance of oil-well cement paste in CO2-rich environments

This work studies the influence of incorporating organo-modified montmorillonite (OMMT) nanoclay in class G cement pastes on chemical and mechanical resistance in CO2-rich environments. Cement paste specimens, with and without added nanoclay (0.5%, 1%, 2% in wt.), were submitted to degradation tests in CO2-saturated water and wet supercritical CO2, at 90 °C and 15 MPa. Scanning electron microscopy, X-ray diffraction, computed X-ray microtomography, pycnometry, Vickers microhardness measurements, and compressive strength tests were used to evaluate the effect of the OMMT nanoclay on the cement paste properties. The addition of 0.5% OMMT nanoclay increased the specific density and the compressive strength of hardened cement paste and decreased chemically modified layer as a result of CO2 attack. However, these effects became less evident with increasing OMMT nanoclay content. Additionally, the Vickers microhardness and compressive strength results suggest that OMMT nanoclay can prevent the high precipitation of carbonates that influences the diffusion of CO2 into cement paste.

Preparation and characterization of novel glycidyl methacrylate/clay nanocomposites

The impact of the type and amounts of nanofiller on the features of the glycidyl methacrylate-co-ethylene glycol dimethacrylate (GMA-co-EGDMA)/organomodified montmorillonite (OMt) nanocomposites that were prepared by in situ radical suspension polymerization, was examined. Cloisite 30B and Cloisite 25A were used in this study as nanofillers, in amounts of 2 and 10 wt.%. The structure, morphology, thermal stability and porosity of the initial GMA-co-EGDMA copolymer and their nanocomposites were examined by ATR-FTIR analysis, wide angle X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), thermogravimetric analysis (TG) and mercury porosimetry. It has been established that both clay nanofillers were successfully incorporated into the structure of the initial copolymer, simultaneously on their surface and also on cross-sectional area. Prepared samples with 2 wt.% have predominantly exfoliated, while samples with 10 wt.% have some tactoids-aggregates structure of the OMt layers. Thermogravimetric analysis revealed that after ~ 30 % of degradation, all nanocomposites become more thermal stable than the initial copolymer. The obtained results indicate that porosity parameters can be easily modified with the addition of clay nanofillers and thus prepared nanocomposites adjusted to specific purposes.

The effect of OMMT reinforcement and annealing treatment on mechanical and thermal properties of Polyurethane Copolymer nanocomposites

This study focuses on a new fabrication of nanocomposite based on Polyurethane Copolymer (PUC) intercalated with organo-modified montmorillonite nanoparticles (OMMT), via an efficient combination of solution mixing and melt blending processes. The combination of solution mixing and melt interaction processes produced PUC/OMMT nanocomposites with enhanced properties. The OMMT filled PUC was characterised by TEM and tensile test. The effect of thermal treatment process was also studied due to subsequent microphase separation of PUC resulting from microdomain miscibility. TEM observation recognised a decent dispersion state of OMMT within PUC, owing to their exfoliated and intercalated structure. This morphology was greatly influenced by induced thermal treatment. The dynamic mechanical thermal analysis (DMTA) revealed that storage modulus and glass transition temperature of the nanocomposites increased with OMMT incorporation. The tensile modulus and tensile strength of nanocomposites showed an improvement with the addition of OMMT.