Polymer Clay Nanocomposites Research Articles

Tensile modulus of clay‐reinforced system supposing the interphase effectiveness for load transferring

AbstractIn this work, we focus on the minimum interfacial shear modulus (Sc) and interfacial shear modulus (Si) controlling the efficiency of interphase zone in polymer clay nanocomposites, since the stress transferring through interphase section handles the stress bearing of samples. The roles of “Sc” and “Si” in the effective thickness and concentration of interphase zone are clarified. Moreover, a model based on Kolarik system is developed for modulus of clay‐reinforced nanocomposites, which reflects the efficiency of interphase zone. The experimental data of tensile modulus for many samples display good matching with the predictions of the advanced model. Also, all model parameters properly manipulate the nanocomposite's modulus. Thick clay (t > 4 nm) cannot generate the interphase zone in the samples. A poor “Sc,” high “Si,” and thin clay improve the modulus of nanocomposites, but very high “Sc,” extremely poor “Si,” or thick clay cause a poor nanocomposite. A high value of Sc = 0.21 GPa deteriorates the reinforcing efficiency of clay in nanocomposites. Furthermore, low Si < 35 GPa produces a poorer nanocomposite than the polymer matrix. Additionally, complete exfoliation of thin clay (t = 1 nm) causes 900% improvement in the nanocomposite's modulus.

Economic Evaluation on the Production of Poly-DADMAC and Sepiolite Nanocomposite

Some agricultural wastes are not suitable for direct disposal to standard sewage treatment plants and pre-treatment is required to avoid clogging by colloidal materials. One of the pre-treatment stages is coagulation and flocculation. In several studies, the mixture of polymer and clay fulfills the properties of coagulant and flocculant materials. A mixture of poly-DADMAC polymer and sepiolite clay can be used as a coagoflocculant at the same time. This study aims to analyze whether a project to manufacture clay polymer nanocomposites is feasible or not. By taking into account various perspectives including engineering and economic perspectives, this project is considered prospective to be carried out. This is indicated by the increase in the Profitability Index (PI) value of 5.33658 in the third year from -0.00975 which was the PI value the previous year. In twenty-four hours, the project can produce approximately 8.25 tonnes of adsorbent. The total profit earned in one year reaches 719,738.04 USD when run under ideal conditions. Apart from the results of the economic analysis mentioned, this project is also very effective in terms of time because it is simple and the raw materials needed are abundant

Parametric investigation of effective elastic properties of exfoliated polymer/clay nanocomposites using a developed mean-field model

A theoretical model is developed to describe the effective elastic modulus of the exfoliated polymer-clay nanocomposites (PCNs). The clay layers are assumed as rectangular cuboid, which are randomly dispersed in the composite. The geometric and mechanical properties of the clay layer, the interphase layer, and the matrix have been considered to analyze the effect of microstructural parameters on the effective strength of PCNs. The predictions of the presented model for experimental data are compared with the Halpin-Tsai model. Furthermore, the experimental elastic modulus and predicted behavior from the theoretical model of the mechanical properties of PCNs are in reasonable agreement.

Preparation and characterization of quaternary ammonium salt and 3-aminopropyltriethoxysilane-modified sericite mica

AbstractModified sericite mica was prepared by combining the intercalation of cetyltrimethylammonium bromide (CTAB) through ion exchange and surface modification of 3-aminopropyltriethoxysilane (KH550) with the following steps: high-temperature activation of sericite mica, acid activation, sodium modification, LiNO3 treatment, the ion-exchange intercalation of the cetyltrimethylammonium cation (CTA+) and surface modification of KH550. High-temperature activation was the most critical step for the modified sericite mica, and the number of hydroxyl groups of mica under high temperature directly affected the surface modification of KH550. The effects of various activation temperatures on the surface modification of sericite mica were investigated. The structure of activated sericite mica was intact when activation temperature was 600°C or 700°C, and the surface modification of sericite mica was not affected. The structure of activated sericite mica was partially destroyed at 800°C. The optimal temperature for activating sericite mica was 700°C. The structure and morphology of modified sericite mica were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Brunauer–Emmett–Teller (BET) analysis and loose bulk volume. The KH550 could not only chemically graft onto the surface of sericite mica, but also enter into the interlayer through electrostatic attraction after its end amino group was protonated. The interlayer spacing of modified sericite mica increased to 3.22 nm, indicating that it might be an excellent layered silicate for preparing clay–polymer nanocomposites.

Cohesive Zone Modeling of the Elastoplastic and Failure Behavior of Polymer Nanoclay Composites

Cohesive zone model (CZM) is commonly used to deal with the nonlinear zone ahead of crack tips in materials with elastoplastic deformation behavior. This model is capable of predicting the behavior of crack initiation and growth. In this paper, CZM-based finite element analysis (FEA) is performed to examine the effects of processing parameters (i.e., the clay nanoparticle volume fraction and aspect ratio) in the mechanical behaviors of a polymeric matrix reinforced with aligned clay nanoparticles. The polymeric matrix is treated as an ideal elastoplastic solid with isotropic hardening behavior, whereas the clay nanoparticles are simplified as stiff, linearly elastic platelets. Representative volume elements (RVEs) of the resulting polymer nanoclay composites (PNCs) are adopted for FEA with the clay nanoparticle distributions to follow both stack and stagger configurations, respectively. In the study, four volume fractions (Vf = 2.5%, 5%, 7.5% and 10%) and four aspect ratios (ρ = 5, 7.5, 10, and 20) of the clay nanoparticles in the PNCs are considered. Detailed computational results show that either increasing volume fraction or aspect ratio of the clay nanoparticles enhances the effective tensile strength and stiffness of the PNCs. The progressive debonding process of the clay nanoparticles in the polymeric resin was predicted, and the debonding was initiated in the linearly elastic loading range. The numerical results also show that PNCs with stagger nanoparticle configuration demonstrate slightly higher values of the engineering stress than those based on the stack nanoparticle configuration at both varying volume fractions and aspect ratios of the clay nanoparticles. In addition, CZM-based FEA predicts a slightly lower stress field around the clay particles in PNCs than that without integration of CZM. The present computational studies are applicable for processing PNCs with controllable mechanical properties, especially the control of the key processing parameters of PNCs, i.e., the volume fraction and aspect ratio of the clay nanoparticles.

Mathematical and finite element analysis estimations of the reinforcement effect on Young's modulus of polymer membrane/montmorillonite clay nanocomposites

AbstractThis work attempts to estimate the effect of the reinforcement percentage on Young's modulus for membranes of polymer‐clay nanocomposites (PCNs). Models tried to simulate different contents of the reinforcement for experimentally obtained PCNs with nanometric montmorillonite clays (MMT) incorporated into a polynorbornene dicarboximide matrix. The analyses were carried out modeling through discrete element method (DEM) and finite element analysis (FEA) volume fractions from 0.01 to 0.025 of elliptical MMT nano‐platelets with aspect ratios = 0.2 (1000 × 500 nm) and thicknesses of 1 nm. These models were generated using as starting point the morphology and distribution of the reinforcements observed in scanning electron microscopy for experimental PCNs. Estimations were compared to predictions obtained by Rule of Mixtures and other mathematical models. Results showed that the elastic modulus of the nanocomposites significantly rises as MMT volume fraction increases. Besides, the use of DEM‐FEA generated the predictions closest to the experimental values, with relative errors lower than 10%. For the other models, the errors were significantly high, even reaching 100%. This shows the importance of DEM‐FEA to obtain a more accurate model of a real composite and a better estimation of its mechanical behavior.

Surface Charges Control the Structure and Properties of Layered Nanocomposite of Cellulose Nanofibrils and Clay Platelets.

The interfacial bonding and structure at the nanoscale in the polymer–clay nanocomposites are essential for obtaining desirable material and structure properties. Layered nanocomposite films of cellulose nanofibrils (CNFs)/montmorillonite (MTM) were prepared from the water suspensions of either CNFs bearing quaternary ammonium cations (Q-CNF) or CNFs bearing carboxylate groups (TO-CNF) with MTM nanoplatelets carrying net surface negative charges by using vacuum filtration followed by compressive drying. The effect of the ionic interaction between cationic or anionic charged CNFs and MTM nanoplatelets on the structure, mechanical properties, and flame retardant performance of the TO-CNF/MTM and Q-CNF/MTM nanocomposite films were studied and compared. The MTM nanoplatelets were well dispersed in the network of TO-CNFs in the form of nanoscale tactoids with the MTM content in the range of 5–70 wt %, while an intercalated structure was observed in the Q-CNF/MTM nanocomposites. The resulting TO-CNF/MTM nanocomposite films had a better flame retardant performance as compared to the Q-CNF/MTM films with the same MTM content. In addition, the effective modulus of MTM for the TO-CNF/MTM nanocomposites was as high as 129.9 GPa, 3.5 times higher than that for Q-CNF/MTM (37.1 GPa). On the other hand, the Q-CNF/MTM nanocomposites showed a synergistic enhancement in the modulus and tensile strength together with strain-to-failure and demonstrated a much better toughness as compared to the TO-CNF/MTM nanocomposites.

Nanoscale Thin Film Corrosion Barriers Enabled By Multilayer Polymer Clay Nanocomposites

Ultrathin nanocomposite films fabricated by layer-by-layer (LbL) assembly are an emerging class of coatings with remarkable barrier performance. Here, we examine LBL polymer-clay nanocomposite (PCN) coatings that afford anti-corrosion properties comparable to those exhibited by more traditional films that are orders of magnitude thicker. PCN barrier thin films comprised of up to 40 bilayers of polyethyleneimine (PEI) and exfoliated laponite (LAP), montmorillonite (MMT), or vermiculite (VMT) clay platelets were coated onto steel plates using a scalable LBL dip-coating process. A combination of electrochemical impedance spectroscopy and ex-situ electron and vibrational spectroscopy were used to evaluate coating performance during exposure in 0.6 M NaCl for up to 7 days. A PEI/VMT crosslinked coating of only 250 nm thick slowed the corrosion rate of mild steel by three orders of magnitude (Rct = 106 vs. 103 Ω-cm2) after seven days in 0.6 M NaCl. This performance exceeded the reported performance of other LBL coatings along with much thicker multilayer composite coatings and several conventional pretreatments on mild steel under similar test conditions. The exceptional performance is attributed to the effective barrier properties imparted by a high loading (>80 wt%) of orientated, high aspect ratio (2000:1) platelet layers in a nanobrick wall morphology. Substitution of VMT with lower aspect ratio clay platelets of either MMT (400:1) or LAP (30:1) showed that coated steel corrosion rates and apparent coating permeability scales with platelet size following LAP > MMT >> VMT. Thus, this study has for the first time shown that platelet aspect ratio is a primary means of improving the performance LbL nanocomposite coatings which is in line with the expected behavior of conventional nanocomposites. Given film debonding from the substrate was observed as a common failure mode during exposure for all coating types, replacement of the PEI polymer component with a more debonding-resistant polymer may be an additional pathway to further improve LbL PCN anticorrosion performance.

Mechanical, thermal and dynamic-mechanical studies of functionalized halloysite nanotubes reinforced polypropylene composites

Mechanical, dynamic-mechanical and thermal performance of polypropylene (PP) composites which are composed of (3-Aminopropyl) triethoxysilane (APTES) functionalized Halloysite nanotubes (HNTs) were investigated. Functionalization of HNTs was confirmed by the presence of amine stretching peaks in the FTIR spectrum. A decrease in the agglomeration and high dispersion of APTES-HNTs across the PP matrix was confirmed by scanning electron micrographs (SEM). The mechanical properties of APTES-HNT-PP polymer composites were superior over their unmodified counterparts. Tensile properties such as maximum strength, Young’s modulus and impact strength were significantly enhanced by 28%, 45% and 60% respectively, with 6 wt% incorporation of surface-modified HNTs into PP matrix. A drastic improvement of stiffness and thermal stability of composites was noted with the incorporation of APTES modified HNTs into PP polymer. Differential scanning calorimetry (DSC) analysis showed a total increase of 22% in the crystallinity of clay polymer nanocomposite after filled with surface-modified HNTs. Overall, the outcome of this research confirms the modification of the surface of HNTs with a silane coupling agent, which enhances the mechanical and thermal performance of PP composites incorporated HNTs.

Investigations on thermo-mechanical properties of organically modified polymer clay nanocomposites for packaging application

Eco-friendly packing polymer materials are in the spotlight but, lack of new biodegradable polymers either natural or synthetic is yet to establish the market more competitively. So, in the present work, clay as a nano-filler is embedded and organically modified in some synthetic and natural polymers which are well established commercially to enhance their biodegradability. The impact of clay on the properties of synthetic polymers namely, poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVAc) and natural polymer cellulose acetate butyrate (CAB) was studied. Results from differential scanning calorimetric (DSC) showed a decrease in the glass transition temperature of organically modified polymer clay nanocomposites (PCC) than pure polymers. Scanning electron microscopy (SEM) displayed a uniform surface with small-sized crystallites distributed on the polymer surface. X-ray diffraction (XRD) spectra revealed the formation of enhanced intercalated structures in PCC. Furthermore, FTIR studies showed that the interlayer bonding (Si–O bands) of pure clay is deformed in PCCs. The tensile strength of PCC increased with an increase in organo-clay loading. This unique mechanical behavior is due to the agglomeration of organo-clay particles. Finally, the biodegradation studies revealed enhanced hydrolytic degradation in PCC than pure polymers. Hence, these PCCs are environmentally friendlier than their pure synthetic polymers without significant compromise in their properties, which makes it suitable for packaging industries.

Effects of critical interfacial shear strength between polymer and nanoclay on the Pukanszky's “B” interphase factor and tensile strength of polymer nanocomposites

This paper aims to develop the “B” interphase parameter and Pukanszky model for tensile strength of polymer clay nanocomposites assuming critical interfacial shear strength (τc) providing the stress transferring between polymer and nanoparticles. The clay properties express the “τc” and both “τc” and interfacial shear strength (τ) develop the effective thickness, strength and volume fraction of interphase region as well as the effective volume fraction of clay in nanocomposites. The effective terms are applied to expand the “B” interphase parameter and Pukanszky equation. The experimental data of tensile strength for some samples and the parametric investigations validate the developed equations for “B” and tensile strength of nanocomposites. All parameters consistently control the “B” and tensile strength. Low critical interfacial shear strength, high interfacial strength, thick interphase, high interfacial shear strength, high aspect ratio (length per thickness) of clay and a small number of clay in the stacks produce a high “B” and improve the tensile strength of nanocomposites. The absence of interphase section in nanocomposites largely decreases the “B” and very thin interphase deteriorates the strengthening efficiency of nanoclay in nanocomposites.

Study on the gear performance of polymer-clay nanocomposites by applying step and constant loading schemes and image analysis

The efficiency of polymer nanocomposites for gear applications is evaluated in this paper. Poly(butylene terephthalate) (PBT) and montmorillonite (MMT) were employed as the polymer matrix and nanoreinforcement, respectively. Gear tests were conducted under 6 and 11 Nm constant torques, determined via step-loading approach. Image processing was employed to calculate gear tooth wear, identify wear patterns, and explore failure mechanisms. The inclusions of MMT reduced tooth surface temperature and wear, at identical durations, relative to neat PBT. The average gear lifespan increased up to 107% and 79% at 6 and 11 Nm loads, respectively, with clay addition. Tooth profile deviation was suppressed for PBT/MMT gears, in contrast to neat PBT, at both applied loads. At 6 Nm, fatigue-induced pitch cracking was predominant for both pristine and nanocomposite gears, while the failure mode at 11 Nm was altered from thermal bending for pure PBT to crack-induced fracture for PBT/MMT gears. The microstructural evaluation of worn teeth indicated the transition of wear mechanism from adhesive for pure PBT to abrasive with smoother worn surface for PBT/MMT gears. Digital image correlation (DIC) was applied to obtain the strain distribution of deformed gear teeth and study its correlation with the applied torque and material composition.

Investigation of the Physico-Chemical Absorption Characterizations of Jute Polymer Clay Nanocomposites as a Function of Chemical Treatments

In this study, jute polyethylene clay nanocomposites were developed using hot press technique. The hydrophilic nature of fiber and nanoclay exhibited poor interfacial interaction to hydrophobic polymer matrix. In order to enhance the interfacial interaction among fiber, polymer, and nanofillers, the chemically treated jute (with benzenediazonium salt, propionic anhydride, and 3-isocyanatopropyltriethoxy silane) and organically modified nanoclay were used for the manufacturing of nanocomposites in this study. The effect of chemical treatments and nanoclay addition on the improvement of absorption characterizations of prepared nanocomposites against water and few chemical reagents have been investigated. It has been observed that the treated jute composites showed higher improvement in absorption properties than raw jute composite and silane treated jute composite found highest value. In addition, nanoclay filled composites showed higher improvement than composite without nanoclay and MMT-1.31PS nanoclay loaded nanocomposite exhibited highest improvement among five types of MMT nanoclay used in this work. The fabricated nanocomposites were resistant to all chemicals used except carbon tetrachloride.

Sodium montmorillonite concentration effect on Bis-GMA/TEGDMA resin to prepare clay polymer nanocomposites for dental applications

The aim of this work was to evaluate the effect of the addition of sodium montmorillonite (Na+Mt) on the flexural strength, flexural modulus, degree of conversion, steady state shear viscosity and complex viscosity of the Bis-GMA (2,2-bis-[4-(methacryloxypropoxy)-phenyl] propane)/TEGDMA (ethane-1,2-diylbis(oxy)) bis (ethane-2,1-diyl) bis(2-methylacrylate) resin. Two types of clay polymer nanocomposites (CPN) were prepared, the first one by using sodium montmorillonite as received (Na+Mt) and the second one by adding sodium montmorillonite previously dispersed in water (Na+Mt/H2O). Sodium montmorillonite was added at different contents: 0.1, 0.2, 0.3, 0.4 parts per hundred of resin (phr) to Bis-GMA/TEGDMA resin for each type of CPN. A Bis-GMA/TEGDMA resin, without sodium montmorillonite, was used as control. Two-way ANOVA and Tukey's test were applied for statistical analysis. Comparisons were performed using a significance level of α = 0.05. Statistical analysis revealed that the addition of sodium montmorillonite as received or dispersed in water, had no effect on flexural strength (p = .886), flexural modulus (p = .809) and degree of conversion of resin (p = .742). Nevertheless, the content of sodium montmorillonite significantly influenced the flexural strength (p = .004) and flexural modulus (p < .001) of the two types of CPN. Flexural strength was increased when 0.1, 0.2 and 0.3 phr of Na+Mt or Na+Mt/H2O was used. Flexural modulus increased when 0.3 and 0.4 phr of Na+Mt or Na+Mt/H2O were added to resin. X-ray diffraction measurements showed that polymer chains were successfully introduced in the interlayer space of the clay mineral producing polymer intercalation. Scanning electron microscopy showed a rough surface for both CPN groups evaluated which evidenced electrostatic interactions between the clay mineral and the polymer matrix. Rheological behavior evidenced the physical interaction between clay mineral layers and polymer matrix. The incorporation up to 0.3 phr of sodium montmorillonite improved the mechanical and chemical properties of the Bis-GMA/TEGDMA resin.

Synthesis and Characterization of Polycaprolactone(PCL)/Organo-Montmorillonite(O-MMT) Blendvia Solvent Casting

Polycaprolactone (PCL) is a hydrophobic, semi-crystalline polymer that has been broadly applied in long term implants, drug release applications, and in the tissue engineering field due to its availability, relatively inexpensive price and suitability for modification. Organo-montmorillonite (O-MMT) clay has been extensively used for various polymer-nanocomposite studies and widely used as adsorbent due to its high specific surface area. Most polymer clay nanocomposites are involved in biomedical applications such as in drug delivery systems and wound healing. In this study, O-MMT was incorporated to PCL via solvent casting, which resulted into film membranes that were characterized to identify its surface morphology, chemical structure, wettability, mechanical property, pore size, and antibacterial properties upon its varying concentrations. The SEM and FTIR results indicated the presence of both PCL and O-MMT within the membrane. The mechanical properties of the film membranes showed an improvement upon reaching an optimal point. An increase in pore size was determined relative to its hydrophilicity. The film membrane showed an antibacterial activity only at the higher concentrations of the O-MMT using the S. aureus strain. As such, the results showed that there is an improvement in the mechanical, wettability, water absorption and antibacterial properties of the PCL with the incorporation of the O-MMT, making it a viable candidate dressing material for wound healing.

Thermal Conductivity Enhancement in Polymer-Clay Nanocomposite Using Casting Techniques

Nowadays, there is a need for efficiency and miniaturization in electronic products. However, in the chip level, heat dissipation can limit the performance of these gadgets. Semiconductor industries addressed this thermal management challenge by using thermal interface material. Previous studies have shown that polymer-clay nanocomposite has an enhanced thermal conductivity which can be used as a thermal interface material. In this study, the aim was to determine the effect of casting techniques on the microstructure and thermal conductivity of the polymer-clay nanocomposites. Solution intercalation method was used in fabricating the 5vol% polymer-clay nanocomposite. Organo-modified montmorillonite (MMT) was dispersed in unsaturated polyester (UP) matrix by means of high frequency ultrasonication and formed using two casting techniques; mold casting and tape casting. Results showed a slight increase in the thermal conductivity coefficient of the tape-casted samples at 2.99 W/m-K compared to the mold-casted samples at 2.87 W/m-K. Transmission electron microscopy (TEM) and x-ray diffraction (XRD) results exhibited dispersed microstructure for both casting techniques. Polymer intercalation of ~16% increase in d-spacing of clay for mold-casted samples and with a ~20% increase in d-spacing of clay for tape-casted samples were observed. With these microstructure modifications, the increase in the thermal conductivity coefficient of the tape-casted samples can be attributed to the shear force employed by the tape casting technique.

Development and characterization of organoclay filled polyetherimide nanocomposites for anticorrosive coatings

Abstract Polyetherimide (PEI)/organically modified Fluorohectorite (OFH) nanocomposite were prepared by dispersing OFH in PEI matrix. The structural as well as morphological characteristics of the nanocomposites were investigated using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The thermal and mechanical properties of the PEI nanocomposites were found to be significantly improved by the incorporation of organically modified flurohectorite nano clay into the PEI matrix. The water uptake of the nanocomposites was investigated in detail as a function of clay content and it was minimum for composites with 3 wt% of filler. The anticorrosion properties of clay polymer nanocomposite (CPN) coatings were evaluated by means of various electrochemical methods which include Electrochemical Impedance Spectroscopy (EIS) and Open Circuit Potential Measurements (OCP). The results obtained from various analyses showed that the PEI/OFH nanocomposites coatings possess better anticorrosion properties.

Effects of critical interfacial shear modulus between polymer matrix and nanoclay on the effective interphase properties and tensile modulus of nanocomposites

Many researchers have investigated the tensile modulus of polymer nanocomposites considering the interphase aspects, but have not considered the minimum interphase modulus that reinforces the nanocomposites. In this research, the critical interfacial shear modulus between polymer and nanoclay (Sc) in nanocomposites is determined mathematically to highlight its effects on the effective interphase properties. In addition, a model for the tensile modulus of polymer clay nanocomposites is developed by considering the clay size, clay morphology, interphase properties, “Sc” and interfacial shear modulus (Si). The predictions of the developed model are compared with experimental data for several samples. Additionally, the model’s calculations for different ranges of all parameters are validated. Good agreement is observed between the calculations and experimental values, validating the accuracy of the proposed model. A poor “Sc” and a high “Si” along with thin and large clay can positively control the efficiency of the interphase region and the modulus of the nanocomposites. A clay thickness (t) of 1 nm and clay length (l) of 11 μm increased the modulus of the polymer matrix by 120%, but for t > 4 nm, or t > 3 nm and l < 4 μm, there was only a 10% improvement in the nanocomposite modulus.

Influence of the dispersing agents to obtain polymer–clay nanocomposites processed in two-steps using thermokinetic mixer

Polymer nanocomposite performance depends not only on the compatibility between nanoparticles and polymer matrix, but also the sequence in which the nanoparticle is incorporated into the polymer and the compounding device applied. In this study, we report the morphology, oxygen permeability, thermal and mechanical properties of the polypropylene nanocomposites change due to the use of a thermokinetic mixer when specific preparation steps are followed based on the dispersing agents used. Two organically modified clays and dispersing agents were applied: montmorillonite and hydrotalcite; hydrogenated hydrocarbon resin and poly (propylene-g-maleic anhydride) as compatibilizer with different maleic anhydride content. For the nanocomposites containing montmorillonite, poly (propylene-g-maleic anhydride), with low maleic anhydride content and the hydrocarbon resin prepared using the thermokinetic mixer, a more efficient clay dispersion was achieved. As a result, an increase in mechanical stiffness (57% in the Young modulus), higher thermal stability and a decrease in oxygen permeability (58%) were obtained. However, samples prepared with hydrotalcite achieved a better distribution and dispersion by preparing directly on a twin-screw extruder. Wherein, higher mechanical stiffness (36% in the Young modulus) with reduction in the oxygen permeability (52%) was reached when poly (propylene-g-maleic anhydride) with low maleic anhydride content and the hydrocarbon resin were present. These results point to that by using the dispersing agents in combined with a proper mixing system is possible to improve polyolefin nanocomposite properties, increasing the range of application in the packaging industry.

Preparation and characterisation of green clay-polymer nanocomposite for heavy metals removal

ABSTRACTNatural polymer Moringa oleifera seed as coagulant and bentonite clay as adsorbent were used for preparing novel composite coagulant. Results obtained from FTIR, SEM, TEM and P-XRD show that the bentonite clay and M. oleifera seed biopolymers physico-chemically interact with each other during the preparation of clay-polymer composite. The FTIR results show that the major functional groups present in bentonite clay and M. oleifera seed are integrated at nano levels in the novel composite to remove heavy metals from aqueous systems. The coagulo-adsorption using clay-polymer composite may be used for the adsorption of heavy metals ions from the aqueous systems. It becomes possible due to the structural characteristics of the clay crystallites together with the functional attraction of the biopolymer and it results in the formation of clay-polymer metal complexes. The clay-polymer nano-composite of M. oleifera seed and bentonite clay showed considerable cadmium, chromium and lead removal property.