Organo-montmorillonite Research Articles

Surface properties of in situ organo-montmorillonite modified wood flour and the influence on mechanical properties of composites with polypropylene

In this study, wood flours (WFs) were modified by sodium-montmorillonite (Na-MMT) and didecyl dimethyl ammonium chloride (DDAC) in two steps to form organo-montmorillonite (OMMT) inside WFs at different OMMT concentrations (0.25, 0.5, 0.75 and 1%, respectively). The surface properties of WFs were investigated as an approach to understand the compatibility of WF/polypropylene (PP) composites. The mechanical properties of the composites were also tested. The results showed that: (1) OMMT modification did not influence the surface morphologies of WFs; (2) owing to the covering of OMMT on WF surface, with increasing OMMT concentration, the surface free energies of WFs increased with both increases of dispersive and polar components, and the surface hydroxyl groups of WF decreased, suggesting good compatibility with non-polar PP; (3) the flexural and tensile strength were correlated with the dispersive component fraction. Significant improvements in flexural and tensile strength were found at OMMT concentration of 0.5%. With increase of OMMT concentration, the flexural and Young's modulus increased. However, the impact strength decreased.

Effect of organic modifier type of montmorillonite on the poly (butyl acrylate-co-methyl methacrylate)/montmorillonite nanocomposite

Nanocomposites based on poly(BA-co-MMA) and organo-montmorillonite (OMt) were synthesized by semi batch emulsion polymerization. OMt was used directly after the organic modification of sodium montmorillonite (Mt). By this way, dispersion of OMt in emulsion polymerization was improved. OMts were prepared by organic modification of Resadiye Mt (bentonite) with five different quaternary ammonium salts (QAS) to observe the effect of structural difference on the poly(butyl acrylate-co-methyl methacrylate) nanocomposites. The affinity of OMts towards organic liquids was observed via swelling test in toluene and butyl acrylate (BA)-methyl methacrylate (MMA) mixture. OMt content in the nanocomposite as well as the effect of QAS structure and dosage was investigated. Good dispersion of OMt in copolymer films was obtained as demonstrated by X-ray diffraction and partially exfoliated OMt structure was determined through transmission electron microscope. Final nanocomposites had 47 wt% solids contents. Nanocomposite containing 2.3 wt% OMt modified with two 18 carbons alkyl chain at excess QAS amount resulted in higher increments of thermal, mechanical, barrier properties and glossiness for coating applications.

The non-micellar template model for porous clay heterostructures: A perspective from the layer charge of base clay

In this paper, the effect of layer charge (LC) of base clay on the structural properties of porous clay heterostructures (PCHs) was studied. Three natural montmorillonites (Mt) with different LC and a series of reduced-charge Mt were used in the synthesis of PCH to discuss the non-micellar template model for PCH from the perspective of base clay. The PCH samples are the intergrowth of a porous silica-intercalated clay and an amorphous silica component. The XRD and TEM studies revealed that the d001-values of PCH samples prepared from natural Mt (simply as “natural PCH” for short) were larger than 3nm. The interstratified structures in PCH samples from reduced-charge Mt (simply as “reduced-charge PCH” for short) were the result of the collapse of interlayer spaces caused by the inhomogeneous LC reduction. The organic carbon contents (fOC) of organo-montmorillonite (OMt) were negatively correlated with the bulk silica contents (fSiO2-b) of the corresponding PCH samples. For the natural PCH, the extra spaces from decreased surfactant within interlayer were occupied by amorphous silica in the pillaring reaction. The decreased specific surface area (SSA), porosity and the invariant dominant pore size (1.3–1.4nm) of PCH suggested that blocking the pore channels in the interlayer spaces with increased silica was more pronounced than propping the layers permanently apart and building porous structures. Based on the effect of organic template and base clay on the structural properties in our previous and present work, Mt-based PCH probably is a type of porous materials with invariant pore size.

Research on the Application Properties of Tpe/Ommt as Mold Materials

The aim of this work was to select one type of polymer as an alternative to room-temperature-vulcanizated silicone rubber (RTV) which was used in the preparation of rubber molds. Thermoplastic elastomer (TPE) and its organo-montmorillonite (OMMT) filled composites were chosen as candidates. Their structure and properties were researched and compared. The properties such as tensile strength, elongation at break, dimensional stability, and thermal stability were studied. The composite with 1 wt% OMMT showed the highest tensile strength and elongation at break, 10.9 MPa and 1313.6%, which was 172.5% and 30.3% higher than that of pure RTV. In addition, this TPE composite exhibited excellent thermal and dimensional stability. At room temperature, the coefficient of linear expansion (COLE) and coefficient of volume expansion (COVE) of the TPE/OMMT-1 wt% was 2.3×10−5 and 7.2×10−4, respectively. This was 87% and 86% lower compared to that of pure RTV, 1.7×10−4 and 5.1×10−3. This dimensional stability was superior to the pure RTV, indicating this composite can be used as an alternative to RTV as mold material to improve the texture fineness of the culture stone. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used in the investigation of the microtopography of the TPE composites. It was revealed that the layered silicates exhibited partial exfoliation with the addition of 1 wt% OMMT in the matrix.

Organo-montmorillonite supported titania nanocomposite synthesized by using poly(methyl methacrylate) grafted cellulose as template and its application in photodegradation

We report a study on the synthesis of a nanocomposite that contains anatase titania (TiO2) particles, organo-montmorillonite (OMMT) and cellulose-g-poly(methyl methacrylate) (cellulose-g-PMMA), and the application of the nanocomposite as a photocatalyst in degradation of 2,4-dichlorophenol (2,4-DCP). The nanocomposite was characterized by Fourier-transform infrared spectra, X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The photocatalytic activity of the nanocomposite was evaluated by the photoreaction of 2,4-DCP. We compared the photocatalytic activity of the nanocomposite in the presence or absence of OMMT, PMMA and TiO2. The photocatalytic activity of the nanocomposite was also compared with commercial TiO2 nanoparticles. The synthetic nanocomposite exhibits the highest photocatalytic activity. After the fourth time recycling, the nanocomposite still maintains more than 90 % of its photocatalytic activity.

Preparation of Poly(phenylene oxide)/Polyamide-6 Nanocomposites with High Tensile Strength and Excellent Impact Performance

Organo-montmorillonite (OMMT) was introduced into SEBS-g-MA toughened poly(phenylene oxide)/polyamide-6 (PPO/PA6) blends simply by melt extrusion. The effects of OMMT on morphology, rheology, and mechanical behaviors of toughened PPO/PA6 nanocomposites were studied by scanning electron microscope, transmission electron microscope, capillary rheometer and mechanical tests. The addition of OMMT could decrease the size of dispersed PPO domains in PA6 matrix and melt viscosity of the toughened PPO/PA6 nanocomposites. Besides, exfoliated OMMT also brought significant improvement of tensile properties and heat deflection temperature (HDT), simultaneously. For nanocomposites with exfoliated OMMT, OMMT induced more core–shell toughening particles with the optimized size, and thus, elastomer-OMMT synergistic toughening was achieved in the PPO/PA6 nanocomposites. Consequently, PPO/PA6 nanocomposites with high tensile strength, excellent impact performance, improved HDT, and good processability were obtained.

Flame retardance property of shape-stabilized phase change materials

Flame retardance of shape stabilized phase change materials (SSPCM) based on paraffin, high density polyethylene (HDPE) and styrene–butadiene–styrene copolymer (SBS) was investigated. The effects of organomontmorillonite (OMMT), expanded graphite (EG) and crosslinking of the polymer matrix were evaluated by means of horizontal burning test, thermogravimetric analysis (TGA) and cone calorimeter. The results showed that the addition of EG and OMMT increased the burning time greatly. The treatment temperature of EG also played an important role owing to the different pore sizes and expansion ratios. When the polymer matrix was crosslinked by tert-butyl hydroperoxide (TBHP), the burning time was further prolonged. TGA results indicated that the vaporization and thermo-oxidation temperature increased and the decomposition of the polymer matrix was hindered in flame retardant SSPCM. The cone calorimeter test demonstrated that the peak heat release rates (PHRR) of flame retardant SSPCM decreased by up to 72.7%, and the formation of CO2 and CO decreased significantly. The horizontal burning tests implied that the best flame retardant performance was achieved in SSPCM containing OMMT/EG/TBHP which has the longest burning time and large amount of char residue. The flame retardant mechanism was also discussed.

Joint Effect of Compatibilizer and Organo-Montmorillonite on Compatibilization of Polyamide-6/Poly(phenylene oxide) Blend: Morphology and Properties

Compatibilizer (styrene–maleic anhydride copolymer, SMA) and organo-montmorillonite (OMMT) were introduced into immiscible polyamide-6 (PA6)/ poly(phenylene oxide) (PPO) blend to obtain quaternary nanocomposites simply by melt extrusion. OMMT tactoids formed in PA6/PPO/OMMT ternary blend would become smaller or disappear with the addition of SMA. Besides, viscosity of SMA compatibilized PA6/PPO blend decreased a lot with the addition of OMMT. Based on these results, a mechanism for joint effect of SMA and OMMT in compatibilizing PA6 and PPO was proposed. We further studied water absorption and tensile properties of the nanocomposites, which were in consistent with the proposed mechanism.

Thermal stability of organo‐montmorillonite‐modified wood flour/poly(lactic acid) composites

In this research, wood flour (WF) was modified using sodium–montmorillonite (Na‐MMT) at four different concentrations (0.5, 1.0, 2.0, and 4.0 wt%, respectively) and didecyl dimethyl ammonium chloride (DDAC) in a two‐step process to form organo‐montmorillonite (OMMT) inside the WF or attached to the WF surface. The thus‐modified WF was then mixed with poly(lactic acid) (PLA) to produce WF/PLA composites. The thermal stability of these composites with respect to their resistance against both thermal deformation and thermal decomposition was characterized by stress relaxation, differential scanning calorimetry (DSC), and thermogravimetric (TG) analysis. Besides, the activation energies for thermal decomposition of the composites were calculated. The results showed the following: (1) The modification of WF by OMMT improved the resistance against thermal deformation of the composites at appropriate OMMT loadings (lower than 1 wt% in this study). However, after introducing excessive OMMT, the enhancements in thermal stability diminished. Composite containing WF modified by 0.5 wt% of OMMT showed the optimal thermal deformation stability in this study, reflected in the highest values of thermal properties such as the glass transition temperature, melting temperature, crystallization temperature, and slowest stress relaxation rate. (2) OMMT showed a negative effect on the resistance against thermal decomposition. Namely, OMMT accelerated the thermal decomposition of the composites, probably by the easier degradation of the organic surfactant used for the WF modification. However, this behavior might be favorable for achieving fire retardancy. POLYM. COMPOS., 37:1971–1977, 2016. © 2015 Society of Plastics Engineers

Effect of organo-montmorillonite on mechanical properties of bismaleimide composites reinforced by glass fibre and carbon fibre

Organo-montmorillonite (OMMT) modified bismaleimide (BMI) nanocomposites were used as the matrix of glass fibre and carbon fibre reinforced composites. The effects of OMMT on the mechanical properties of BMI resin and fibre composites were investigated. Fourier transform infrared spectroscopy (FT-IR) analysis revealed that there exist interactions between OMMT and resin, which is useful for the delamination and dispersion of the silicate layers within the BMI matrix. Owing to the incorporation of OMMT, the impact strength, flexural strength and modulus of BMI resin were substantially improved. Moreover, the interlaminar shear strength (ILSS), flexural strength and modulus of fibre composites were enhanced. Scanning electron microscopy (SEM) photographs exhibited that the destruction modes of fibre composites were changed from interfacial destruction into the matrix destruction after the introduction of OMMT. In addition, it was found that the interfacial adhesion of glass fibre composite was improved more significantly than that of carbon fibre composite.

Characterization and properties of organo-montmorillonite modified lignocellulosic fibers and their interaction mechanisms

In this study, cellulose fiber/flour (CF) and lignin flour (LF) separated from poplar wood flour (WF) as well as xylan as a representative of hemicellulose flour (HF), were modified with organo-montmorillonite (OMMT) through a two-step method.

Combination of montmorillonite and a Schiff-base polyphosphate ester to improve the flame retardancy of ethylene-vinyl acetate copolymer

Abstract Different flame retardant ethylene-vinyl acetate copolymer (EVA) formulations were prepared to evaluate the synergistic effect between organo-montmorillonite (OMMT) and a Schiff-base polyphosphate ester (PAB) on the combustion behavior of EVA. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed that montmorillonite platelets selectively dispersed in the PAB phase. EVA/PAB/OMMT(80/15/5) had better thermal stability and flame retardancy than EVA/PAB(80/20), as indicated by the results of thermogravimetric analysis (TGA), limited oxygen index (LOI), vertical burning test (UL-94) and microscale combustion colorimeter (MCC), showing a synergism between OMMT and PAB. For example, the onset decomposition temperature (T 5%) increased from 233°C to 296°C, the char residue at 600°C increased from 6.6% to 11.0%, and the peak heat release rate (PHRR) decreased from 718.1 W/g to 706.6 W/g. This is caused by the silicoaluminophosphate (SAPO) structure formed by reactions between the phosphoric acid generated from PAB and OMMT.

A comparison of various ionic surfactant modifiers used in in situ synthesis of organo-montmorillonite inside wood flour

In this study, organo-montmorillonite (OMt) was in situ synthesized inside the wood flour (WF) by using sodium-montmorillonite (Na+-Mt) and ionic surfactant modifiers as raw materials. Six different surfactants, including didecyl dimethyl ammonium chloride (DDAC), dodecyl dimethyl benzyl ammonium chloride (BAC), hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfonate (SDS), sodium dodecyl benzene sulfonate (SDBS), and sodium stearate (SSTA) were selected for a comparative analysis. The thus-modified WF samples were characterized. Their hygroscopicities and mechanical properties were tested. The results showed that: (1) in most groups, Na+-Mt transformed to OMt and uniformly distributed in WF cell wall, forming intercalated structures; (2) in most groups, OMt reduced the hygroscopicity of WF as well as improved the modulus of elasticity and hardness significantly; (3) DDAC and SDS were the best cationic and anionic surfactant modifiers in modified Na+-Mt, respectively. Compared with the anionic surfactant modified groups, cationic ones were better.

Preparation and properties of natural rubber/organo-montmorillonite: from lab samples to bulk material

<p>Focusing on application aspects of the rubber nanocomposites and the production and testing of industrial-sized samples, this study was performed in two phases. First, natural rubber (NR)/organo-montmorillonite (OMMT) nanocomposites containing 2–14 phr OMMT were prepared on a laboratory-sized two-roll mill. The vulcanization behavior and mechanical properties of NR/OMMT composites were compared with a referent NR compound containing 60 phr carbon black (N330) as a reinforcing filler. The x-ray diffraction (XRD) analyses showed a predominant intercalated structure for all OMMT nanocomposites. As a result, the organoclay behaved as an effective reinforcement for NR, even at loadings as low as 2 phr. This nanocomposite exhibited an improvement in tensile strength of 29% and in elongation at break of 61% in comparison with the referent NR/N330 compound. With the estimated optimal filler content, in the second phase, bulk NR/OMMT-5/steel samples were successfully produced for dynamic testing. The dynamic moduli were investigated by the method of forced vibrations. Compared to the NR/N 330 samples, NR/OMMT-5 samples showed improved hysteresis, with very low dissipating energy per cycle and significantly reduced Mullins effect.</p>

Ultrasound assisted continuous‐mixing for the preparation of PP/SEBS/OMMT ternary nanocomposites

ABSTRACTPolypropylene (PP)/polystyrene‐block‐poly(ethylene‐co‐butylenes)‐block‐polystyrene (SEBS)/organo‐montmorillonite (OMMT) nanocomposites of varying concentrations of maleic anhydride‐grafted polypropylene (PP‐g‐MA) were prepared by continuous mixing assisted by ultrasonic oscillation. The structure and morphology of nanocomposites were investigated by X‐ray diffraction (XRD), transmission electron microscopy, and scanning electron microscopy. It was found that both PP‐g‐MA and ultrasonic oscillation could enhance the intercalation and exfoliation of OMMT in PP matrix. Meanwhile, the formation of PP could be induced by ultrasonic irradiation at a power of more than 540 W. Rheological properties including complex viscosity, storage, and loss modulus of nanocomposites were increased after adding PP‐g‐MA or ultrasonic treatment. The results of mechanical properties showed that PP‐g‐MA could improve the tensile strength and tensile modulus of nanocomposites, but with the sacrifice of impact strength. This problem could be improved by ultrasound due to the reduced particle size of SEBS. However, the mechanical properties would be reduced by ultrasonic treatment with higher intensity due to the polymer degradation. Therefore, the synergistic effect of both compatibilizer and ultrasound should account for the balance between toughness and stiffness of PP/SEBS/OMMT ternary nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41202.

Clean production of CTAB-montmorillonite: formation mechanism and swelling behavior in xylene

Organo-montmorillonite (OMt) with high swellability in a hydrophobic medium such as xylene was successfully prepared. The process was realized by clean and simple modification of Ca2+-montmorillonite (Ca2+-Mt) with cetyltrimethylammonium bromide (CTAB) dispersed in very small amounts of water and ethanol. In the process, there were no needs for the steps of a Na+-exchange reaction and washing. The mechanisms of formation of OMt and its swellability in xylene were investigated. The distribution of cetyltrimethylammonium (CTA+) cations and CTAB molecules adsorbed in the interlayer spaces, CTAB molecules adsorbed on the external surfaces and free CTAB molecules in the resultant OMt products was determined by the thermogravimetric (TG) and differential thermogravimetry (DTG) of the washed and unwashed OMt. The arrangement models of CTA+ cations in the interlayer spaces were deduced from powder X-ray diffraction (XRD) patterns and Fourier transform infrared (FT-IR) spectra. The results suggested that CTA+ cations and CTAB molecules adsorbed in the interlayer spaces and CTAB molecules adsorbed on the external surfaces of OMt played a role in the modification of Ca2+-Mt by ion exchange, hydrophobic interactions and van der Waals forces. Addition of ethanol into the preparation mixture was favorable for binding more CTA+ cations and CTAB molecules in the interlayer spaces of OMt and enhanced dispersion of clay particles. A maximal 64.0% colloid yield in xylene for the OMt sample, which was higher than that of the commercial OMt produced by a multistep process, was achieved. The formation of good gel-like structure of OMt in xylene depended on proper distribution of CTAB molecules and CTA+ cations on the external and internal surfaces of OMt, ordered arrangements of CTA+ cations in the interlayer spaces of OMt and the small sizes of dispersed OMt particles. A large volume of the networks of OMt particles in xylene was formed by edge-to-edge, face-to-face and face-to-edge between neighboring Mt particles and multifacial linking.

Preparation and Dimensional Stability of Organo-Montmorillonite (O-MMT) Treated Unsaturated Polyester Hybrid Composites Filled with Keratin Fiber

O-MMT treated unsaturated polyester based hybrid composites were prepared using keratin fiber obtained from chicken feathers. Fibers of similar dimension were selected to fabricate composites through hand lay-up method. The preparation and dimensional stability properties of keratin fiber as reinforcements in composites is outlined in this paper. Varying O-MMT contents in nancomposites is performed to investigate the effects on the dimensional stability (water absorption and thickness swelling) of the composites. Results indicated that increasing fiber content deteriorates dimensional stability of the composites and composites. However, improvements in dimensional stability of the keratin fibercomposites were observed with O-MMT. O-MMT treatment reduces the water absorption and thickness swelling, especially at 5wt% of O-MMT concentrationat all range of fiber content. At 5wt% concentration of O-MMt, 10wt% keratin fiber content marks the lowest water absorption and thickness swelling with rate of 0.65% and 1.93%, respectively. Adopting 10wt% of keratin fiber at 5wt% of O-MMT can be utilized for application requiring high dimensional stability.

Synthesis of Organo-Montmorillonite/Sodium Alginate Graft Poly(Acrylic Acid -Co-2-Acrylamido-2-Methyl-1-Propane Sulfonic Acid) Superabsorbent Composite and Its Adsorption Studies

A new superabsorbent composite based on the natural material sodium alginate (SA) was synthesized by intercalation graft polymerization of SA, acrylic acid (AA), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and organo-montmorillonite (OMMT) using ammonium persulfate (APS) as an initiator and N,N'-methylenebisacrylamide (MBA) as a cross linker. The composite was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), and was used to remove heavy metal ions such as Pb2+, Ni2+ and Cu2+ from aqueous solutions. Maximum adsorption capacities for Pb2+, Ni2+ and Cu2+ were 1485, 303 and 294 mg/g respectively. It was found that the adsorption of Pb2+ was consistent with both the Langmuir and the Freundlich model, while that of Ni2+ and Cu2+ was in accordance with the Langmuir model. Mechanisms for the adsorption process were speculated upon. It revealed that chelation was dominant for the adsorption of Pb2+, while ion-exchange played an important role for adsorption of Ni2+ and Cu2+. The superabsorbent composite had good reuse performance in wastewater treatment.

Thermal and Mechanical Properties of Ultra High Molecular Weight Polyethylene Fiber Reinforced High-Density Polyethylene Homocomposites: Effect of Processing Condition and Nanoclay Addition

A new method to prepare single-polymer high-density (HDPE)-ultra high molecular weight polyethylene (UHMWPE) fiber (PE-PE homocomposites) composed and also PE-PE homocomposites containing HDPE organo montmorillonite clay (OMMT) nanocomposites as a matrix (PE nanohomocomposites) was used. Owing to the major importance of fiber impregnation by the matrix and its effect on the adhesion of matrix/fiber and, consequently, the mechanical properties of the composite, a combination of powder impregnation and film stacking methods, utilizing compression molding, were used for manufacturing the PE-PE homocomposites and PE nanohomocomposites. In addition, PE nanohomocomposites with the matrix containing different amounts of nanoclay were prepared to investigate the effect of the clay on the interfacial and mechanical properties of the PE-PE nanohomocomposites. Several different processing conditions were examined to determine the best conditions for manufacturing of the PE-PE homocomposite and PE nanohomocomposites and it was concluded that 40 bar and 10 min of compression molding resulted in the highest overall mechanical properties. The PE-PE homocomposites and PE-PE nanohomocomposites showed identical trends for the relationship between the effects of processing conditions and mechanical properties. Mechanical results demonstrated that clay platelets could increase the interfacial strength by improving physical entanglements between fiber and matrix through better cocrystallization.

Physical, mechanical, and thermal properties of micronized organo-montmorillonite suspension modified wood flour/poly(lactic acid) composites

In this study, micronized organo-montmorillonite (OMMT) suspension was prepared with sodium-montmorillonite (Na-MMT), didecyl dimethyl ammonium chloride, and dispersant polyethylene glycol 1000 by a ball-milling process. Then, wood flours (WFs) were impregnated with prepared OMMT suspension at a concentration of 0.5, 1.0, 2.0, or 4.0%. WFs were characterized by X-ray diffraction and scanning electron microscopy. The hygroscopicity of WF was investigated by a vapor adsorption method. WFs were, respectively, blended with poly (lactic acid) (PLA) to produce WF/PLA composites. Thereafter, physical, mechanical, and thermal properties of the composites were tested. The results showed that a great amount of OMMT attached on the surface of WF, partly penetrating into the microstructure of WF. Owing to the hydrophobicity of OMMT, the vapor adsorption of OMMT-modified WF decreased. The composite which was produced by WF treated with 0.5% OMMT suspension, showing an increment in the physical, mechanical, and thermal properties. However, OMMT should not be overloaded. Otherwise, the accumulation of OMMT might cause poor interfacial adhesion between WF and PLA matrix. POLYM. COMPOS., 36:731–738, 2015. © 2014 Society of Plastics Engineers