Organically Modified Montmorillonite Content Research Articles

Effects of Quercetin and Organically Modified Montmorillonite on the Properties of Poly(butylene adipate-co-terephthalate)/Thermoplastic Starch Active Packaging Films.

The poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) film stands out owing to its acceptable price, low impact on the environment, and excellent mechanical properties. The main objective of this study was to improve the antioxidant properties of the PBAT/TPS film by incorporation of quercetin (Q) through the extrusion blow process. Another specific objective was to incorporate the organically modified montmorillonite (OMMT) to prolong the release of Q and improve the poor barrier properties of the PBAT/TPS/Q film. The films were analyzed in terms of their morphology, mechanical properties, gas and water barrier properties, and antioxidant and anti-UV properties. Optimization of the OMMT content resulted in a fiber-like, co-continuous morphology of the PBAT/TPS/Q film. The incorporation of quercetin enhanced the antioxidant and anti-UV properties of the PBAT/TPS film, while OMMT improved the mechanical properties, ultraviolet barriers, and gas and water barrier properties. The results show that the films incorporating Q and OMMT provided the oxygen and water barrier by up to 94 and 54%, respectively. Also, the amount of polymer required for 50% 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition is as low as 0.03 g, and the UV transmission rate was reduced by about 50%. Moreover, PBAT/TPS/Q/OMMT films successfully delayed the decay of the banana and blueberry due to their excellent antioxidant properties and suitable water vapor permeability.

Thermal and mechanical characterization of OMMT nano clay treated ABS parts via acetone deposition technique

Presently, the Additive Manufacturing (AM) technique being used for the fabrication of end use products, but its application is restricted due to lack integrity in the surface quality because of its layer upon layer building technique. Hence, further improvement in the AM process are depends on the post processing of 3D printed parts and advancements in the materials being processed by AM technique. In recent years, use of nanoclay has gained considerable attraction due to its superior quality compared to pristine material. Montmorillonite nanoclay has versatile nanoparticles and has potential to enhance the part properties. This work discusses the utilization of organically modified montmorillonite (OMMT) nanoclay for the post treatment of the FDM 3D printed Acrylonitrile Butadiene Styrene (ABS) parts via chemical deposition technique. In this work, compatibility of OMMT with ABS was investigated. ABS parts were fabricated by commercial FDM machine and further, nanoparticles were deposited over the printed parts through by acetone bathing. OMMT in varying amount (2, 4, and 6 wt%), and immersion time (30, 50, and 70 Sec) were selected as the compatibilizer. The treated parts were evaluated for mechanical and thermal properties. The microstructure of treated parts was observed by optical microscope and analyzed by low angle XRD. The specimen treated with 4% nanoclay with 70 sec immersion time showed the better surface smoothness and also increased tensile & flexural strength and elastic & flexural modulus of 38.85 MPa & 48.63 MPa and 2.9 GPa & 1.8 GPa respectively. The parts treated with 6% OMMT nanoclay with 70 sec immersion time showed least (4.48 × 10–5C−1) expansion coefficient. It is also observed that, Tg value also increases from 101 to 106 0C with increase of OMMT content from 2 to 6 wt%. The surface treatment approach showed a competent way to improve the thermal and mechanical properties of FDM parts.

Surface Laser-Marking and Mechanical Properties of Acrylonitrile-Butadiene-Styrene Copolymer Composites with Organically Modified Montmorillonite.

In this study, organically modified montmorillonite (OMMT) was prepared by modifying MMT with a cationic surfactant cetyltrimethylammonium bromide (CTAB). The obtained OMMT of different loading contents (1, 2, 4, 6, and 8 wt %) was melt-blended with poly(acrylonitrile-co-butadiene-co-styrene) (ABS) to prepare a series of ABS/OMMT composites, which were laser marked using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser beam of 1064 nm under different laser current processes. X-ray diffraction (XRD), color difference spectrometer, optical microscope, water contact angle tests, scanning electron microscope (SEM), and Raman spectroscopy were carried out to characterize the morphology, structure, and properties of the laser-patterned ABS composites. The effects of the addition of OMMT and the laser marking process on the mechanical properties of ABS/OMMT composites were investigated through mechanical property tests. The results show that the obtained ABS/OMMT composites have enhanced laser marking performance, compared to the ABS. When the OMMT content is 2 wt % and the laser current intensity is 9 A, the marking on ABS composites has the highest contrast (ΔE = 36.38) and sharpness, and the quick response (QR) code fabricated can be scanned and identified with a mobile app. SEM and water contact angle tests showed that the holes, narrow cracks, and irregular protrusion are formed on the composite surface after laser marking, resulting in a more hydrophobic surface and an increased water contact angle. Raman spectroscopy and XRD indicate that OMMT can absorb the near-infrared laser energy, undergo photo thermal conversion, and cause the pyrolysis and carbonization of ABS to form black marking, and the crystal structure itself does not change significantly. When the 2 wt % of OMMT is loaded, the tensile strength, elongation at break, and impact strength of ABS/OMMT are increased by 15, 20, and 14%, respectively, compared to ABS. Compared with the unmarked ABS/OMMT, the defects including holes and cracks generated on the surface of the marked one lead to the decreased mechanical property. The desirable combination of high contrast laser marking performance and mechanical properties can be achieved at an OMMT loading content of 2 wt % and a laser current intensity of 9 A. This research work provides a simple, economical, and environmentally friendly method for laser marking of engineering materials such as ABS.

Effect of Polysulfone/Organomontmorillonite Blends on Nanocomposite Membrane Properties

In this study, an organically modified montmorillonite (OMMT) hydrophilic clay was incorporated in PSf through non-solvent induced phase separation fabrication process to improve its properties. Afterwards, hand casting was done and the PSf/OMMT membranes produced were characterized to determine the effect of OMMT addition to its structural, mechanical and thermal properties, and hydrophilicity. Scanning electron microscope (SEM) images of the surfaces showed a denser surface as the OMMT content increases but the pores on the images were not pronounced unlike the SEM images of the cross-section which depicted spherical macrovoids for 1.0% while wider macrovoids were observed for 3.0% and 5.0% OMMT. The mechanical properties of the nanocomposite with clay content up to 3.0% were improved. The glass transition temperatures of the PSf/OMMT nanocomposites were lower than the pure PSf while no significant difference was observed for the melting point. By statistical analysis, the addition and variation of the clay concentrations has no significant effect to the thermal properties. The hydrophilicity of the membranes improved with the increasing OMMT concentration, but was found to be insignificant. The overall data gathered showed that the clay addition had improved characteristics compared to the pure PSf membrane, which implies that PSf/OMMT nanocomposite could be likely used in filtration applications.

A facile strategy for preparing Gemini surfactant‐modified montmorillonite and its effect on the morphology and mechanical properties of polyethylene/polystyrene

A facile method was proposed to control the morphology and enhance the ultimate mechanical properties of polyethylene/polystyrene (PE/PS) by incorporating Gemini‐surfactant‐ organically modified montmorillonite (OMMT). OMMT was synthesized and incorporated into the immiscible PE/PS to fabricate composites. The effect of OMMT modified with a surfactant of different carbon chain length on the morphology and the final properties of the immiscible PE/PS polymer composites were investigated. FTIR and X‐ray diffraction characterizations revealed OMMT was successfully synthesized. Scanning electron microscopy observation revealed the morphologies of the PE/PS (70/30, w/w)/OMMT composites gradually transformed from “sea‐island” into the co‐continuous structure with the increase of the OMMT loading. The elongation at break of the PE/PS compatibilized with 1.5 wt% of Gemini C10‐MMT can reach as high as 700%. When compared with the PE/PS without OMMT, the flexural strength and modulus of the PE/PS/OMMT composites also have a remarkable enhancement with OMMT content. The flexural modulus of the PE/PS/OMMT composites with 1.5 wt% Gemini C10‐MMT was increased by 22%. POLYM. COMPOS., 40:3254–3263, 2019. © 2018 Society of Plastics Engineers

Synergistic effects of organically modified montmorillonite on the flame-retardant and smoke suppression properties of transparent intumescent fire-retardant coatings

A series of novel montmorillonite polyphosphate (OPEA) flame retardants were successfully synthesized by chemical grafting of cyclic phosphate ester acid (PEA) with different contents of organically modified montmorillonite (OMMT). Their chemical structures were confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). Five types of transparent fire-retardant coatings applied to plywood boards were prepared by mixing melamine formaldehyde resin with PEA or OPEAs. The transparency analysis reveals that chemical grafting of PEA on the surface of OMMT imparts a high degree of transparency to the resulting fire-retardant coatings due to the uniform dispersion and completely exfoliated states of the MMT platelets in the coatings, as determined from X-ray diffraction patterns and transmission electron microscopy images. The fire protection tests show that the introduction of OMMT decreases the mass loss, char index, and flame spread rating of the coatings, concomitant with an increase in the intumescent factor. The cone calorimeter and smoke density tests reveal that incorporation of OMMT remarkably decreases the heat release and smoke production of the coatings, which is ascribed to a more thermally stable, compact and intumescent char layer formed during combustion, judging from digital photographs and scanning electron microscopy images. Further, the synergistic flame-retardant and smoke suppression effects of OMMT in the coatings depend on the content of OMMT, and excessive OMMT will decrease the synergistic effects. The thermo-gravimetric analysis shows that the thermal stability and residual weight of the coatings increase efficiently with increasing OMMT content. The FTIR and elemental analysis demonstrate that the incorporation of OMMT generates more phosphorus-rich cross-linked char and aromatic char in the condensed phase, thus effectively reducing the heat release, smoke production, and mass loss of the coatings.

Polypropylene/organically modified‐grafted mica/organoclay hybrid nanocomposites: Preparation, characterization, and mechanical properties

Polypropylene (PP) was reinforced using both an organically modified‐grafted mica (OMGM) and an organically modified montmorillonite (OMMT) as debonding rigid nanoparticles to improve its impact resistance with the advantage of increasing its Young's modulus and crack growth resistance. For this purpose, mica was organically modified using diacetone acrylamide, a double bond‐ended modifier. To improve further the polymer/nanoparticle interfacial interactions and delamination of layered particles, PP graft maleic anhydride was grafted on the modified mica. Various amounts of OMMT, 0–3 wt% along with 1 wt% OMGM were used to reinforce the PP matrix. The effect of OMMT content on the crystallinity degree, fracture morphology and mechanical properties of resultant hybrid nanocomposites was investigated. The results showed that the incorporation of 1 wt% OMGM and 0.5 wt% OMMT resulted in the highest impact resistance (68%) and fracture toughness (5.7%) when compared with neat PP. In addition, the elastic modulus and yield stress were increased 12 and 14.5%, respectively. Transmission electron microscopy exhibited a fairly good dispersion of smaller OMMT and longer OMGM tactoids in the resultant hybrid nanocomposite. A slower crack growth rate was observed for the hybrid nanocomposite because of the barrier property of the silicate layers against the crack propagation when compared with the neat PP. However, increasing of the OMMT content caused the nanoparticle agglomeration and lowering the impact resistance in the resultant hybrid nanocomposites. POLYM. COMPOS., 40:1718–1730, 2019. © 2018 Society of Plastics Engineers

The effects of the location of organoclay on the structure and mechanical properties of compatibilized polypropylene/polyamide‐12 ternary nanocomposites

Ternary nanocomposites (NCs) were obtained by melt‐mixing maleic anhydride‐modified polypropylene (gPP) with previously prepared polyamide‐12 (PA12)/organically modified montmorillonite (OMMT) NCs. During melt‐mixing, OMMT migrated from the PA12 phase to the gPP/PA12 interphase. Moreover, a critical concentration of OMMT was found to saturate the interphase and, at higher contents, the excess OMMT migrated to the gPP matrix. When compared with the unfilled gPP/PA12 blends, the addition of OMMT caused a change in the microstructure. The average size of the PA12 dispersed particles in the NCs was found to be independent of the OMMT content. At OMMT contents below the critical concentration, that is, when the OMMT located at the interphase, Young's modulus remained practically unchanged and the ductile nature of the ternary NCs maintained. However, at higher OMMT contents, Young's modulus increased linearly and the NCs became brittle, due to the presence of OMMT in the gPP matrix. POLYM. ENG. SCI., 58:830–838, 2018. © 2017 Society of Plastics Engineers

Effect of montmorillonite on the flame-resistant and mechanical properties of intumescent flame-retardant poly(butylene succinate) composites

Organically modified montmorillonite (OMMT) was used as synergist to enhance the flame-retardant and mechanical properties of poly(butylene succinate)/intumescent flame retardant (PBS/IFR) composites. The flame-retardant, thermal degradation and combustion properties of PBS and its flame-retardant composites were characterized by limiting oxygen index (LOI) test, vertical burning (UL-94) test, thermogravimetric analysis, cone calorimeter and scanning electron microscopy, respectively. The results indicate that PBS/IFR composites exhibit excellent flame retardance when OMMT is at an appropriate content. PBS/IFR composite with 20 wt% IFR and 1.5 wt% OMMT has an LOI of 40.1% and can pass the UL-94 V0 rating. The synergistic effect between OMMT and IFR on the flame-retardant properties of PBS depends on the content of OMMT, and excessive OMMT diminish this synergistic effect. The possible flame-retardant mechanism of OMMT on PBS/IFR composite is proposed. The results of mechanical test also indicate that OMMT can effectively increase the notched impact strength of PBS/IFR composites.

Characterization of clay nanoparticle-containing poly(vinylidene fluoride–trifluoroethylene) copolymer for piezoelectric sensors

Abstract Organically modified montmorillonite (OMMT) was added to a poly(vinylidene fluoride–trifluoroethylene) P(VDF-TrFE) copolymer at different concentrations (0–3 wt%) to increase its piezoelectric and mechanical properties. Additionally, three different treatments of heating-cooling, electrical poling, and pressing were used to enhance the β -phase fraction in P(VDF-TrFE)/OMMT (PVTO) composite films. Furthermore, various experimental tests (tensile, creep, and electromechanical) were carried out to assess the feasibility of PVTO film sensors for health monitoring of composite structures. From the results, it was proved that the effect of OMMT on the formation of β -phase in P(VDF-TrFE) was caused mainly by the ion-dipole interactions between P(VDF-TrFE) and OMMT. The sequential process of “heating-cooling-pressing-electrical poling” (heating: 140 °C for 24 h, cooling: −10 °C, pressing: 30 MPa for 15 min, electrical poling: 80 MV/m for 30 min) was the most effective way to maximize the β fraction in PVTO. PVTO sensors successfully survived in a carbon/epoxy laminate, generating electrical signals of 1.6, 1.8, 2, and 4 V for PVTO with an OMMT content of 0, 1, 2, and 3 wt%, respectively, under a periodic compressive force of 177 kPa.

Multifunctional zirconium oxide doped chitosan based hybrid nanocomposites as bone tissue engineering materials

This paper reports the development of multifunctional zirconium oxide (ZrO2) doped nancomposites having chitosan (CTS), organically modified montmorillonite (OMMT) and nano-hydroxyapatite (HAP). Formation of these nanocomposites was confirmed by various characterization techniques such as Fourier transform infrared spectroscopy and powder X-ray diffraction. Scanning electron microscopy images revealed uniform distribution of OMMT and nano-HAP-ZrO2 into CTS matrix. Powder XRD study and TEM study revealed that OMMT has partially exfoliated into the polymer matrix. Enhanced mechanical properties in comparison to the reported literature were obtained after the addition of ZrO2 nanoparticle into the nanocomposites. In rheological measurements, CMZH I–III exhibited greater storage modulus (G′) than loss modulus (G″). TGA results showed that these nanocomposites are thermally more stable compare to pure CTS film. Strong antibacterial zone of inhibition and the lowest minimum inhibition concentration (MIC) value of these nanocomposites against bacterial strains proved that these materials have the ability to prevent bacterial infection in orthopedic implants. Compatibility of these nanocomposites with pH and blood of human body was established. It was observed from the swelling study that the swelling percentage was increased with decreasing the hydrophobic OMMT content. Human osteoblastic MG-63 cell proliferations were observed on the nanocomposites and cytocompatibility of these nanocomposites was also established. Moreover, addition of 5wt% OMMT and 5wt% nano-HAP-ZrO2 into 90wt% CTS matrix provides maximum tensile strength, storage modulus, aqueous swelling and cytocompatibility along with strong antibacterial effect, pH and erythrocyte compatibility.

Effect of organically modified montmorillonite (OMMT) on biodegradation of PS:PLA and PS:PLA:OMMT using Phanerochaete chrysosporium

The environmental issues of synthetic polymers have been resolved using biodegradation under controlled conditions. The degradation study of polymeric composites of (a) polystyrene (PS) and poly(lactic acid) (PLA) (PS:PLA), and (b) PS:PLA filled with organically modified montmorillonite (OMMT) (PS:PLA:OMMT) was carried out using Phanerochaete chrysosporium. PLA was synthesized using l‐lactic acid under controlled ultrasound cavitation technique, dried and added to a solution of PS. Surface of montmorillonite (MMT) was modified using column chromatographic technique to improve d‐spacing up to 31.5 Å. The sheets of PS:PLA and PS:PLA:OMMT were subjected to degradation study in minimal medium using P. chrysosporium micro‐organism under controlled conditions up to 28 days. The growth of micro‐organism and fractures inside the polymer matrix before and after degradation was observed using scanning electron microscope. Change in extracellular protein content, biomass production, and % degradation with respect to time of incubated samples have been also studied. It was found that the PS:PLA:OMMT (at 5 phr OMMT content) and PS:PLA (at 30% PLA) composites show an increment in degradation. The presence of OMMT leads to faster degradation of PS:PLA:OMMT nanocomposites, which decreases in mechanical property by 30% of PLA and 5 wt% of OMMT content. POLYM. COMPOS., 38:1292–1301, 2017. © 2015 Society of Plastics Engineers

Organically modified montmorillonite polymer nanocomposites for stereolithography building process

Novel photopolymerizable nanocomposite formulations, able to photopolymerize with a dual curing mechanism (cationic and radical), were developed, characterized and used in the stereolithography (SL) process for the construction of 3D objects with a very simple geometry. The influence of the presence of organically modified montmorillonite (OM) nanoparticles on the reactivity of the photopolymerizable liquid mixtures was firstly analyzed, as function of the amount of nanofiller, by photocalorimetric analysis (p‐DSC). The basal distance of OM before and after mixing with the photocurable formulation was characterized by X‐ray diffraction. Composites with higher content of OM show an intercalated structure. An exfoliated structure was instead observed in the composites with the lowest OM content, after photocuring in the SL apparatus. These results were also confirmed by the morphological analysis performed by SEM. The glass transition temperature of nanocomposites, photocured by stereolithography, was finally measured by TMA and DSC techniques, confirming that the photocurable formulation loaded with the lowest amount of OM presents improved properties than the unloaded formulation. Copyright © 2014 John Wiley & Sons, Ltd.

Utilization of natural montmorillonite modified with dimethyl, dehydrogenated tallow quaternary ammonium salt as reinforcement in almond shell flour–polypropylene bio-nanocomposites

The main goal of this work was to evaluate the technical feasibility of almond shell flour (ASF) as wood substitute in the production of wood–plastic composites (WPCs). The effects of organically modified montmorillonite (OMMT), as reinforcing agent, on the mechanical and physical properties were also investigated. In order to improve the poor interfacial interaction between the hydrophilic Lignocellulosic material and hydrophobic polypropylene matrix, maleic anhydride grafted polypropylene (MAPP) was added as a coupling agent to all the composites studied. In the sample preparation, OMMT and ASF contents were used as variable factors. The morphology of the specimens was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The results of mechanical properties measurements indicated that when 3wt.% OMMT were added, tensile and flexural properties reached their maximum values. At high level of OMMT loading (5wt.%), increased population of OMMT lead to agglomeration and stress transfer gets blocked. The addition of OMMT filler decreased the water absorption and thickness swelling of composites. SEM study approved the good interaction of the almond shell flour with the polymer as well as the effectiveness of OMMT in improvement of the interaction. TEM study revealed better dispersion of silicate layers in WPCs loaded with 3wt.% of OMMT. The improvement of physico-mechanical properties of composites confirmed that OMMT has good reinforcement and the optimum synergistic effect of OMMT and ASF was achieved at the combination of 3 and 50wt.%, respectively. The findings indicated that almond shell as agro-waste material is a valuable renewable natural resource for composite production and could be utilized as a substitute for wood in composite industries.

Effects of the loading levels of organically modified montmorillonite on the flame‐retardant properties of asphalt

ABSTRACTThe flame‐retardant properties of asphalt for some building applications are very important. In this study, we mainly focused on the influence of organically modified montmorillonite (OMMT) on the flame‐retardant and other properties of asphalt in a large content range and explored suitable contents of OMMT for modified asphalts. Modified asphalts with different contents of OMMT from 2 to 15 wt % were prepared by melt blending. The X‐ray diffraction results revealed that the intercalated structure was formed in the OMMT‐modified asphalt. Rubber processing analysis results indicated the formation of a filler–network structure in the OMMT‐modified asphalt. The limiting oxygen index and cone calorimetry results suggested that OMMT could be used as efficient and ideal flame retardants of asphalt. The results also reveal that excess OMMT contents (i.e., >10 wt %) depredated the flame‐retardant performance of the modified asphalt. We analyzed the mechanism by taking into account of the features of the modified agent for OMMT. The experimental data showed that the viscosity, softening point, and penetration index of the OMMT‐modified asphalt increased with increasing OMMT content, but the ductility decreased slightly when the OMMT content was not beyond 7 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 10.1002/app.40972.

Influence of nano‐organomontmorillonite on the viscoelasticity of the poly(trimethylene terephthalate)/glass fiber/organomontmorillonite hybrid nanocomposites materials

The influences of organically modified montmorillonite (OMMT) on the viscoelasticity of poly(trimethylene terephthalate)/glass fiber/OMMT (PTT/GF/OMMT) hybrid nanocomposite materials at liquid, elastic and glassy states, respectively, were investigated by using the rotational rheometer and dynamic mechanical analyzer (DMA). The viscoelasticity results suggest that OMMT has many important influences on the structure, modulus and toughness of the hybrid nanocomposite materials. At melton state, the shear‐thinning phenomena of the hybrid composite melts become remarkable with increasing OMMT content. At low frequency, the shear storage modulus (G′) and shear loss modulus (G″) of the melts increase with increasing OMMT content. The melt's elastic response increases by OMMT, and OMMT improves the creep resistance of the melts; in addition, the stress relaxation of the hybrid composite melts become slow with increasing OMMT content, and the stress leavings becomes much higher with increasing OMMT content. At glassy state, the storage modulus of the hybrid nanocomposites increases with increasing OMMT content, while the materials' loss modulus increases first and then decreases with increasing OMMT content; therefore, OMMT nanosheets have reinforcement effect on the composites, and it also has definite toughening effect on the hybrid composite when the OMMT content is no >2 wt%. At rubbery state, the hybrid composites show lower decreasing storage modulus but have lower cold‐crystallization ability than that of pure PTT and PTT/GF composite. POLYM. COMPOS., 35:795–805, 2014. © 2013 Society of Plastics Engineers

Transport of organic solvents through natural rubber/nitrile rubber/organically modified montmorillonite nanocomposites

The article describes the transport phenomenon of some commonly used laboratory organic solvents which differ in their solubility parameter value through polymer blend nanocomposites membrane prepared by melt mixing. The three solvents that were used are hexane, toluene and xylene which differed widely in their solubility parameter values. The motivation for the study was to know the effect of solubility parameter on the diffusion transport properties of NR/NBR (natural rubber/nitrile rubber) blends. The solvent uptake, diffusion, sorption and permeation constants were investigated and were found to decrease with organically modified montmorillonite (OMt) content at lower loading. The mode of transport through NR/NBR nanocomposites was found to be anomalous. The difference in solubility parameter value greatly influenced the transport properties. The dependence of various properties on OMt content was supported by morphological analysis data. The effect of blend ratio, solvent size and OMt loading on the diffusion of aromatic and aliphatic solvents through NR/NBR blend systems were investigated. The swelling coefficient values also decreased upon the addition of fillers indicating the presence of hindered path for solvents to diffuse into the polymer matrix. The better reinforcement at lower filler loading was confirmed from the cross-link density values and mechanical properties. The transport data obtained were applied to mathematical models for predicting the diffusion behaviour through nanocomposite membranes and to elucidate the physical mechanism of transport. .

Shrinkage and mechanical properties of unsaturated polyester reinforced with clay and core–shell rubber

Glassy unsaturated polyester (UP) resin was reinforced using an organically modified montmorillonite (OMMT) and toughened with core–shell rubber (CSR) particles. The nanostructure, morphology, and deformation mechanism of composite specimens were studied by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and reflected optical microscopy (ROM). An intercalated nanostructure with partial exfoliation was observed in the UP reinforced by various amounts of OMMT. Locally clustered but globally good CSR particle dispersion in the UP matrix was evident in UP toughened with 5 and 10 wt% CSR particles. Simultaneous presence of OMMT and CSR particles in UP/OMMT/CSR hybrid composites was found to cause partial phase separation with bigger rubber particle agglomerates and lower clay-intergallery height increase. The effects of OMMT and CSR contents on volume shrinkage, impact fracture energy, fracture toughness, and compressive yield strength of UP were investigated. The introduction of OMMT of up to 3 wt% into the UP matrix lowered volume shrinkage to some extent, while further addition increased the shrinkage slightly. In the hybrid nanocomposites, the volume shrinkage decreased to a minimum level of 5.2 % with increases in OMMT level. The impact fracture energy of UP improved with increasing the OMMT level of up to 3 wt%, whereas its further addition decreased the impact fracture energy slightly due to the clay particle agglomeration. The hybrid composites with OMMT level below 3 wt% showed higher impact fracture energy compared to the reinforced UP specimens with the same OMMT levels. Interestingly, a synergism in the fracture toughness (KIC) was observed in the hybrid composite containing 1 wt% OMMT and 10 wt% CSR particles. The presence of OMMT as reinforcement in the hybrid composites could compensate the lowering of the compressive yield strength caused by low-modulus CSR particles. The clay–rubber particle interaction in the hybrid systems seems to increase the threshold of shear deformation of the UP matrix to some extent.

Morphology and mechanical properties of EVA/OMMT nanocomposite foams

Nanocomposite foams based on ethylene vinyl acetate (EVA) copolymer had been prepared by melt blending EVA with the addition of organically modified montmorillonite (OMMT). The clay interlayer spacing was characterized by x-ray diffraction (XRD). The morphology of the foamed samples was studied using transmission electron microscopy and the cell microstructure was characterized by scanning electron microscope. The cell size distribution of the foamed samples was discussed. The effect of OMMT content in the foamed samples on the cellular structure and mechanical properties had been investigated. It had been shown that the OMMT layer could be used as a heterogeneous nucleation agent to decrease the cell size. The uniformity of cell structure of the foamed samples was improved and the physical properties of EVA/OMMT nanocomposite foams were enhanced by the addition of OMMT.

Preparation and Properties of Organically Modified Montmorillonite/Nitrile Rubber Nanocomposites

A series of organically modified montmorillonite (OMMT)/nitrile rubber (NBR) nanocomposites were prepared by a simple mechanical-mixing method. The structures of OMMT and the dispersion of OMMT in the rubber matrix were detected by X-ray diffraction (XRD). The mechanical properties of the NBR/OMMT nanocomposites were characterized, and the tribological behaviors of the nanocomposites were evaluated on a ring-block (MRH-3) wear tester. The results showed that the OMMT was homogeneously dispersed in the NBR matrix. The tensile strength of the OMMT/NBR nanocomposites increased with increasing OMMT contents. Both the coefficient of friction (COF) and wear of the nanocomposites decreased remarkably with increasing OMMT content. In addition, the influence of the applied load on the tribological properties of the nanocomposites is discussed. It is expected that the research may be of aid in the rational design and use of solid, self-lubricating nanocomposites under different loading states.