High performance epoxy resin nanocomposites containing both organic montmorillonite and castor oil-polyurethane

Summary Epoxy resin/polyurethane interpenetrating polymer network nanocomposites with various contents of organophilic montmorillonite (oM-EP/PU nanocomposites) were prepared by a sequential polymeric technique and an in situ intercalation method. X-ray diffraction(XRD), and transmission electronic microscopy(TEM) analysis showed that organophilic montmorillonite (oMMT) disperses uniformly in epoxy resin/polyurethane interpenetrating networks(IPNs), and the intercalated or exfoliated microstructures of oMMT are formed. Differential scanning calorimetry(DSC) test proved that oMMT promotes the compatibility of EP phase and PU phase, and glass transition temperature(T_g) of oM-EP/PU nanocomposites improves with increasing oMMT content. Mechanical properties tests and thermal gravity analysis (TGA) indicated that oMMT and the IPNs of EP and PU exhibit synergistic effect on improving mechanical and thermal properties of pure EP. The mechanism of toughing and reinforcing of oM-EP/PU nanocomposites was further discussed by scanning electronic microscope(SEM).     

Synthesis,characterization and properties of organoclay‐modified polyurethane/epoxy interpenetrating polymer network nanocomposites

organoclay‐modified polyurethane/epoxy interpenetrating network nanocomposites (oM‐PU/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polyurethane and epoxy resin (PU/EP) which had been prepared by a sequential polymerization technique. Wide‐angle X‐ray diffraction (WAXD) and transmission electronic microscopy (TEM) analysis showed that the interpenetrating process of PU and EP improved the exfoliation and dispersion degree of oMMT. The effects of the NCO/OH ratio (isocyanate index), the weight ratio of PU/EP and oMMT content on the phase structure and the mechanical properties of the oM‐PU/EP nanocomposites were studied by tensile testing and scanning electronic microscopy (SEM). Water absorption tests showed that the PU/EP interpenetrating networks and oMMT had synergistic effects on improvement in the water resistance of the oM‐PU/EP nanocomposites. Differential scanning calorimetry (DSC) analysis showed that PU was compatible with EP and that the glass transition temperature (T_g) of the oM‐PU/EP nanocomposites increased with the oMMT content up to 3 wt%, and then decreased with further increasing oMMT content. The thermal stability of these nanocomposites with various oMMT contents was studied by thermogravimetric analysis (TGA), and the mechanism of thermal stability improvement was discussed according to the experimental results. Copyright © 2005 Society of Chemical Industry     

Synthesis and characterization of polyurethane/epoxy interpenetrating network nanocomposites with organoclays

Summary Novel nanocomposites with varying contents of organophilic montmorillonite (oMMT) were prepared by intercalating oMMT to interpenetrating polymer networks (IPNs) of polyurethane and epoxy resin (PU/EP). The PU/EP networks and the oMMT modified PU/EP IPNs nanocomposites were studied with Fourier transform infrared spectrometry, scanning electronic microscopy, transmission electronic microscopy, wide-angle X-ray diffraction, water absorption and tensile test. The results show that oMMT and the IPNs of polyurethane and epoxy resin exhibit synergistic effect on the phase structure and morphology of the IPNs nanocomposites. The addition of oMMT to the PU/EP IPNs matrix provides two fold benefits to the properties of the IPNs nanocomposites. oMMT has not a distinct effect on chemical structure of PU/EP IPNs but promotes the compatibility and phase structure of the IPNs, and the forced compatibility of PU and EP in interpenetrating process improves the dispersion degree of oMMT. Both the mechanical properties and water resistance of the PU/EP IPNs nanocomposites are superior to those of the pure PU/EP IPNs.     

Morphologies and properties of epoxy resin/layered silicate–silica nanocomposites

A new nanofiller containing layered organo‐modified montmorillonite (oMMT) and spherical silica (SiO₂) was prepared by an in situ deposition method and coupling agent modification. Fourier transform infrared spectrometry, X‐ray diffraction and transmission electron microscopy show that there are interactions between oMMT and SiO₂, and the spherical SiO₂ particles are self‐assembled on the edge of oMMT layers, forming a novel layered–spherical nanostructure. An epoxy resin (EP)/oMMT–SiO₂ nanocomposite was obtained by adding oMMT–SiO₂ to EP matrix. Morphologies and mechanical and thermal properties of the new ternary nanocomposite were investigated. For purposes of comparison, the corresponding binary nanocomposites, i.e., EP modified with either oMMT or SiO₂, were also tested. The results for the mechanical properties show that oMMT obviously improves the strength of EP, and SiO₂ enhances the toughness of EP, but oMMT–SiO₂ exhibits a synergistic effect on toughening and reinforcing of EP. The toughening and reinforcing mechanism is explained by scanning electron microscopy. In addition, the thermal resistance of EP/oMMT–SiO₂ is better than that of EP/SiO₂, but it is worse than that of EP/oMMT. Copyright © 2006 Society of Chemical Industry     

Preparation and properties of polyurethane/montmorillonite nanocomposites cured under room temperature

The polyurethane/C₁₆C₁₈‐MMT (the montmorillonite modified with cetyloctadecyldimethyl ammonium bromide) nanocomposites were synthesized by intercalative polymerization and cured under room temperature. The d‐spacing and the dispersion of the C₁₆C₁₈‐MMT in the nanocomposites were measured by X‐ray Diffraction (XRD) and Transmission Electron Microscope (TEM). The mechanical and thermal properties of the nanocomposites were measured by Universal Testing System, Electric Anti‐fold Instrument, Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). It was found out that introducing C₁₆C₁₈‐montmorillonite (MMT) in the polyurethane (PU) displayed good mechanical properties and thermal stability. Rheology behavior in liquid state showed that the addition of the C₁₆C₁₈‐MMT to PU resulted in low gel time and high viscosity. POLYM. COMPOS. 27:470–474, 2006. © 2006 Society of Plastics Engineers.     

Surface modification of Cr2O3 nanoparticles with 3-amino propyl trimethoxy silane (APTMS). Part 1: Studying the mechanical properties of polyurethane/Cr2O3 nanocomposites

The surface of Cr₂O₃ nanoparticles was modified with various amounts of 3-amino propyl trimethoxy silane (APTMS). Thermal gravimetric analysis (TGA), turbidimeter and Fourier transform infrared (FTIR) spectroscopy were utilized in order to investigate APTMS grafting on the nanoparticles. Then, polyurethane nanocomposites were prepared using various loadings of silane modified Cr₂O₃ nanoparticles. The nanoparticles dispersion in the coating matrix was studied by a field emission scanning electron microscopy (FESEM). Dynamic mechanical thermal analysis (DMTA) and tensile test were utilized in order to investigate the mechanical properties of the nanocomposites. Results obtained from FTIR, TGA and turbidimeter measurements revealed that the organic functional groups of the silane were successfully grafted on the surface of the nanoparticles. The mechanical properties of the polyurethane were significantly enhanced using 2 wt% Cr₂O₃ nanoparticles modified with 0.43 g silane/5 g pigment compared with other samples.     

Preparation of novel hydrophobic magnetic Fe3O4/waterborne polyurethane nanocomposites

Magnetic Fe₃O₄/waterborne polyurethane nanocomposites were synthesized based on waterborne polyurethane (WPU) and amino-functionalized Fe₃O₄ by in situ polymerization. The Fe₃O₄ nanoparticle was found to be uniformly distributed in Fe₃O₄/WPU nanocomposites with linear or crosslinked structure. In addition, the formation mechanism and magnetic conduction mechanism of stable inorganic–organic nanocomposites were discussed. The experimental results showed that the thermal stability, magnetic, and mechanical properties of magnetic Fe₃O₄/waterborne polyurethane nanocomposites were improved by amino functionalized Fe₃O₄. Furthermore, the defoaming property of the emulsion and the hydrophobic property of magnetic Fe₃O₄/waterborne polyurethane nanocomposites were improved by the 1-hexadecanol-terminated prepolymer. What more, polycaprolactone (PCL)-based Fe₃O₄/WPU nanocomposites have excellent mechanical properties (The tensile strength is over 30 MPa, the elongation rate is above 300%.) and magnetic properties. Magnetic Fe₃O₄/waterborne polyurethane nanocomposites will be used in the field of hydrophobic and microwave absorbent materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48546.     

Rectorite/thermoplastic polyurethane nanocomposites. II. Improvement of thermal and oil‐resistant properties

Organ‐rectorite/thermoplastic polyurethane (OREC/TPUR) nanocomposites were synthesized via melt intercalation. The dynamic mechanical properties by dynamic mechanical analysis (DMA), thermal and oil‐resistant properties were investigated. The results show that the storage modulus (E′), loss modulus (E″), and glass‐transition temperature (T_g) of the nanocomposites have an increase to some extent than those of pure TPUR. The thermal stability of nanocomposites was also studied in detail by thermal gravity analysis (TGA), which was higher than that of pristine TPUR matrix when the content of organic REC is at 2 wt %, and the decomposition temperature at 10% weight loss of OREC/TPUR is greatly increased up to 330°C from 315°C. Oil uptake of the composites is also significantly reduced in comparison with TPUR matrix, which is ascribed to the good barrier effect of nanosheets of OREC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1165–1169, 2005     

Development of Functional Polyurethane–ZnO Hybrid Nanocomposite Coatings from Thevetia peruviana Seed Oil

The present article reports eco‐friendly multi‐functional polyurethane–ZnO hybrid nanocomposite coatings obtained from Thevetia peruviana seed oil (TPSO). Initially, the polyols were prepared by treating TPSO with glycerol and the formation was supported by Fourier transform infrared (FT‐IR) and ¹H‐NMR studies. In the next stage, siloxane functionalized ZnO nanoparticles were added to the polyol mixture in different weight percentages (0, 1 and 2 %) and then treated with excess 4,4′‐diisocyanatodicyclohexylmethane (H₁₂MDI) in order to synthesize isocyanate terminated polyurethane nanocomposites. The polyurethane hybrids were then casted as thin films and cured under atmospheric moisture. After complete curing they were characterized by using FT‐IR, ¹H‐NMR, ¹³C‐NMR, X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, and dynamic mechanical thermal analysis techniques. The hybrid nanocomposites showed superior thermo‐mechanical and anti‐corrosive properties compared to pristine polyurethane. Also, due to the presence of nano ZnO in the polyurethane matrix, the composite coatings are showing excellent resistance towards various bacterial and fungal stains.     

The Influence of Crysnanoclay Addition on Mechanical and Thermal Properties of Thermoplastic Polyurethane Elastomeric with Polycarbonate Nanocomposites

A series of crysnanoclay-loaded thermoplastic polyurethane (TPU) elastomer/polycarbonate (PC) nanocomposites have been prepared using twin screw extruders. The physicomechanical properties such as tensile behaviors, flexural properties and impact strength of the composites have been reported. Significant improvement in tensile modulus and flexural modulus were noticed for nanocomposites. The thermal characteristics of nanocomposites have been determined by thermogravimetric analysis (TGA) techniques. Thermal degradation kinetic parameters such as energy of activation (E_a) have been calculated from TGA thermograms for the nanocomposites using three mathematical models namely; Coats–Redfern, Horowitz – Metzger and Broido's methods and the results are compared. The effect of crysnanoclay on the storage modulus (E′), loss modulus (E″), and damping factor (tan δ) as a function of temperature have been measured by dynamic mechanical analysis (DMA). The storage moduli of nanocomposites have been increased after incorporating crysnanoclay in polymer matrix.     

Preparation and characterization of novel transparent Eu(AA)3-polyurethane acrylate copolymeric materials

The rare earth (RE) salts Eu(AA)₃ (AA: acrylic acid group) and the macromonomers of polyurethane acrylate (MPUA) containing vinyl groups at the end of the chain are prepared for achieving a novel transparent Eu(AA)₃-polyurethane acrylate (Eu-PUA) materials by copolymerization. The structure and properties of the Eu(AA)₃ and the Eu-PUA have been systematically characterized by infrared spectroscopy (FTIR), proton and carbon nuclear magnetic resonance (¹H-NMR, ¹³C-NMR), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and fluorescence spectrophotometer. It is proved that the Eu(AA)₃ have been successfully bonded onto the molecular chains of the polyurethane acrylate and the glass transition temperature (T_g) of the polyurethane acrylate increases at the presence of Eu(AA)₃. In addition, the Eu-PUA materials show favorable thermal stability and transparence. Typically, the fluorescence spectra show that the strongest fluorescence emission peak of the Eu-PUA material appears at 614 nm at the excitation wavelength of 395 nm. This demonstrates that such material can be applied to functional optical materials in the future. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The Effect of WS2 Nanotubes on the Properties of Epoxy-Based Nanocomposites

In this paper we evaluated the effect of embedding inorganic nanotubes (INT) of tungsten disulfide (WS₂) in an epoxy matrix, on the mechanical, thermal and adhesion properties of the resulting nanocomposites. The nanotube content spanned a range of values (0, 0.1, 0.3, 0.5 and 1.0 wt%), and the nanotube incorporation process consisted of a combination of both distributive (magnetic stirring) and dispersive (ultrasonic mixing) methods. The adhesion of the nanocomposites to an aluminum substrate was characterized by both a single lap shear and a T-peel test. The fracture toughness (K _IC) of the nanocomposites was characterized by a standard compact tension (CT) plane-strain fracture test. The thermal properties of the nanocomposites were determined by dynamic mechanical thermal analysis (DMTA). Overall, the addition of INT-WS₂ was found to improve the shear strength and peel properties of the nanocomposite, and to significantly improve its fracture toughness and glass transition temperature. The extent and character of the nanotube–epoxy interaction were examined by electron microscopy, as was the energy dissipation mechanisms during fracture.     

Preparation and characterization of thermoplastic polyurethane/organoclay nanocomposites by melt intercalation technique: Effect of nanoclay on morphology,mechanical, thermal,and rheological properties

Nanocomposites based on thermoplastic polyurethane (TPU) and organically modified montmorillonite (OMMT) were prepared by melt blending. Organically modified nanoclay was added to the TPU matrix in order to study the influence of the organoclay on nanophase morphology and materials properties. The interaction between TPU matrix and nanofiller was studied by infrared spectroscopy. Morphological characterization of the nanocomposites was carried out using X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy techniques. The results showed that melt mixing is an effective process for dispersing OMMT throughout the TPU matrix. Nanocomposites exhibit higher mechanical and thermal properties than pristine TPU. All these properties showed an increasing trend with the increase in OMMT content. Thermogravimetric analysis revealed that incorporation of organoclay enhances the thermal stability of nanocomposites significantly. Differential scanning calorimetry was used to measure the melting point and the glass transition temperature (T_g) of soft segments, which was found to shift toward higher temperature with the inclusion of organoclays. From dynamic mechanical thermal analysis, it is seen that addition of OMMT strongly influenced the storage and loss modulus of the TPU matrix. Dynamic viscoelastic properties of the nanocomposites were explored using rubber process analyzer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Structural,thermal, and mechanical properties of silanized boron carbide doped epoxy nanocomposites

In the presented study, the structural, thermal, and mechanical properties of the nanocomposites were investigated by doping silanized hexagonal boron carbide (h-B₄C) nanoparticles in varying proportions (0.5%, 1%, 2%, 3%, 4%, and 5%) into the epoxy resin by weight. For this purpose, the surfaces of h-B₄C nanoparticles were silanized by using 3-(glycidyloxypropyl) trimethoxysilane (GPS) to improve adhesion between h-B₄C nanoparticles and epoxy matrix. Then, the silanized nanoparticles were added to the resin by ultrasonication and mechanical stirring techniques to produce nanocomposites. The bond structure differences of silanized B₄C nanoparticles (s-B₄C) and nanoparticle doped composites were investigated by using Fourier transform infrared spectroscopy. Scanning electron microscopy and energy dispersion X-ray spectroscopy (SEM-EDS) technique was used to examine the distribution of nanoparticles in the modified nanocomposites. Differential scanning calorimetry and thermogravimetric analysis techniques were used to determine the thermal properties of the neat and s-B₄C doped nanocomposites. The tensile test and dynamic mechanical analysis were performed to determine the mechanical properties. When the experimental results were examined, changes in the bonding structure of the s-B₄C nanoparticles doped nanocomposites and significant improvements in the mechanical and thermal properties were observed. The optimum doping ratio was determined as 2% by weight. At this doping ratio, the T_g, tensile strength and storage modulus increased approximately 18%, 35%, and 44% compared to the neat composite, respectively.     

Synthesis and characterization of a novel thermally stable water dispersible polyurethane and its magnetic nanocomposites

In this work, a novel water dispersible polyurethane (WDPU) was synthesized from the reaction of hydroxyl-terminated polybutadiene (HTPB), 2,2 bis(hydroxymethyl) propionic acid (DMPA), and 1,5-naphthalene diisocyanate (NDI) and its magnetic nanocomposites were prepared by incorporation of modified Fe₃O₄ by 3-aminopropyltriethoxysilane (Fe₃O₄@APTS) nanoparticles (0.5, 1.5, and 3 wt%) via in situ polymerization method. Use of NDI as a high melting point diisocyanate by having the rigid naphthalene structure imparts physical strength as well as thermal stability to the resulted polyurethane. The synthesized WDPU based on NDI was characterized by using Fourier transform infrared spectroscopy (FTIR) technique. In addition, the morphology, mechanical, and magnetic features of the prepared polyurethane nanocomposites were investigated by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM), magnetic force microscopy (MFM), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMTA), and vibrating sample magnetometer (VSM) methods, respectively. Data from DLS experiment showed that the average particles size of the WDPU nanocomposites increased by increasing the nanoparticle contents in comparison with bare WDPU. AFM and MFM analyses indicated that the magnetic nanoparticles (MNPs) were well dispersed in the polyurethane matrices via the formation of covalent bonding between the functionalized magnetic nanoparticles and polymer chains. TGA results demonstrated that adding MNPs increased the temperature of the thermal degradation of the polyurethane nanocomposite. VSM analysis showed that the super paramagnetic behavior of the prepared nanocomposites depended on the Fe₃O₄@APTS nanoparticle content, as well.     

Novel one‐step synthesis of acrylonitrile butadiene rubber/bentonite nanocomposites with (3‐Mercaptopropyl)trimethoxysilane as a compatilizer

Acrylonitrile butadiene rubber (NBR)/bentonite (Bt) nanocomposites were synthesized by an one‐step method in NBR latex with (3‐Mercaptopropyl)trimethoxysilane (MPTMS) as a compatilizer. The nanocomposites were compounded with curing additives and then vulcanized. The prepared vulcanizates were characterized by Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). The curing properties and mechanical properties were also investigated. The thermal properties were studied with thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology was investigated by field emission‐scanning electron microscopy (FE‐SEM). By swelling test, the swelling ratio and the crosslinking density were achieved. The hydrolyzation and condensation of MPTMS was identified by FTIR while the intercalated/exfoliated structure of Bt was determined by XRD. It was evident that the mechanical properties of the nanocomposites were significantly improved compared with the neat NBR. The well‐dispersed bentonite particles and effects of MPTMS were supported by the images from FE‐SEM. The results of TGA showed that the fastest weight‐loss temperature (T_max) was elevated by over 10°C for the nanocomposites compared with the neat NBR, indicating an enhanced thermal stability. By swelling test, the swelling ratio was determined, decreased to 139% for the optimized NBR/MPTMS/Bt nanocomposites compared with 210% for neat NBR. POLYM. COMPOS., 36:1693–1702, 2015. © 2014 Society of Plastics Engineers     

Preparation and characteristics of nitrile rubber (NBR) nanocomposites based on organophilic layered clay

The effect of clay modification on organo‐montmorillonite/NBR nanocomposites has been studied. Organo‐montmorillonite/NBR nanocomposites were prepared through a melt intercalation process. NBR nanocomposites were characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), dynamic mechanical thermal analysis (DMTA) and a universal testing machine (UTM). XRD showed that the basal spacing in the clay increased, which means that the NBR matrix was intercalated in the clay layer galleries. On TEM images, organo‐montmorillonite (MMT) particles were clearly observed, having been exfoliated into nanoscale layers of about 10–20 nm thickness from their original 40 µm particle size. These layers were uniformly dispersed in the NBR matrix. The DMTA test showed that for these nanocomposites the plateau modulus and glass transition temperature (T_g) increased with respect to the corresponding values of pure NBR (without clay). UTM test showed that the nanocomposites had superior mechanical properties, ie strength and modulus. These improved properties are due to the nanoscale effects and strong interactions between the NBR matrix and the clay interface. Copyright © 2003 Society of Chemical Industry     

Preparation,Mechanical and Thermal Properties of Polyurethane/Nanosilica Composites via High Pressure Shearing Methods

Nanosilica particles were dispersed into polymer diols by high pressure shearing homogenizer (HPSH), then polyurethane nanocomposites were prepared via in-situ polymerization of diphenylmethane diisocyanate (MDI) and polymer diols. FTIR analysis indicated that the -NCO groups of MDI had reacted with the hydroxy on the surface of nanosilica during in-situ polymerization. TGA suggested that polyurethane/nanosilica composites obtained by in-situ polymerization had better thermal stability than pure polyurethane. Meanwhile, the tensile and dynamic mechanical properties of the samples prepared by HPSH were superior to those by directly ultrasonic dispersing nanosilica, accompanied by more homogeneous dispersion of nanosilica particles in the polymer matrix.     

Preparation and Characterization of Polyurethane/ZnO Nanoparticle Composites

The polyurethane/ZnO nanoparticle composites were prepared by in situ suspension polymerization. FT-IR results indicated that hydroxy groups on the ZnO nanoparticles reacted with isocyanate groups, which could improve the compatibility between ZnO nanoparticles and polyurethane to give better properties of nanocomposites. The polyurethane/ZnO nanoparticle composites showed the excellent tensile break strength. The effect of the ZnO nanoparticles on the damping properties were investigated by dynamic mechanical thermal analysis (DMTA). The nanoparticles affected the damping behaviors and significantly increased the values of the tan δ. The main reason was the significant formation of “core-shell” structure in the matrix.     

Development of biodegradable cellulose‐g‐poly(butyl acrylate)/kaolin nanocomposite with improved fire retardancy and mechanical properties

The main aim of the work is to convert a low cost renewable biopolymer to a high performance fire‐retardant biomaterial by modification via grafting. Cellulose, a linear and most abundant biomacromolecule, has gained increasing attention for its interesting properties and potential applications in the synthesis of polymer nanocomposites. Cellulose has been grafted with butyl acrylate via emulsifier free emulsion polymerization using in situ developed transition metal complex initiating system: CuSO₄/glycine/ammonium persulfate with and without additive kaolin to prepare nanocomposites and copolymer, respectively. The morphology of so‐prepared grafted nanocomposites was characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, and field emission scanning electron microscopy. The enhancement in thermal behavior and mechanical properties of nanocomposites over copolymer were outstanding. The fire‐retardant properties were evaluated by limiting oxygen index and cone calorimetry test. The biodegradation and water absorbency of the fire‐retardant nanocomposites have been carried out for better commercialization and environmental concern. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45968.