Nanocomposites from Polycaprolactone (PCL)/Soy Protein Isolate (SPI) Blend with Organoclay

New biobased, ecofriendly nanocomposites were prepared from polycaprolactone (PCL)/soy protein isolate (SPI) blend (80/20 wt/wt) with organically modified clay, by melt compounding. X-ray diffraction and transmission electron microscopy analysis revealed that an intercalated nanocomposite was formed and the silicate layers of the clay were uniformly dispersed at a nanometer scale in matrix polymer. There was great enhancement of both tensile and dynamic mechanical properties in the nanocomposite. A rheological study revealed that the nanocomposite exhibits strong shear-thinning behavior in the melted state, and a percolated network of clay particles was formed in the melted state.     

Synthesis and characterization of elastomeric polyurethane and PU/clay nanocomposites based on an aliphatic diisocyanate

This investigation reports preparation of polyurethane and polyurethane/clay nanocomposites based on polyethylene glycol, isophorone diisocyanate (IPDI), an aliphatic diisocyanate and 1,4‐ Butanediol as chain extender by solution polymerization. In this case PU/clay nanocomposites were prepared via ex‐situ method using 1, 3, and 5 wt % of Cloisite 30B. Thermogravimetric analysis showed that the maximum decomposition temperature (T_max) of the PU/clay nanocomposite is much higher than the pristine PU. The tensile properties improved upon increasing the organoclay (Cloisite 30B) content upto 3 wt %, and then decreased to some extent upon further increasing the nanoparticle loading to 5 wt %. Optical properties of the nanocomposites were studied by UV‐vis spectrophotometer. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) were used to study the morphology of the nanocomposites. It was observed that with the incorporation of 3 wt % nanoclay the crystallinity in PU nanocomposite increases, then diminishes with further loading. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3328–3334, 2013     

Poly(vinyl alcohol) nanocomposites with different clays: Pristine clays and organoclays

Poly(vinyl alcohol) (PVA)/clay nanocomposites were synthesized using the solution intercalation method. Na ion‐exchanged clays [Na⁺–saponite (SPT) and Na⁺–montmorillonite (MMT)] and alkyl ammonium ion‐exchanged clays (C₁₂–MMT and C₁₂OOH–MMT) were used for the PVA nanocomposites. From the morphological studies, the Na ion‐exchanged clay is more easily dispersed in a PVA matrix than is the alkyl ammonium ion‐exchanged clay. Attempts were also made to improve both the thermal stabilities and the tensile properties of PVA/clay nanocomposite films, and it was found that the addition of only a small amount of clay was sufficient for that purpose. Both the ultimate tensile strength and the initial modulus for the nanocomposites increased gradually with clay loading up to 8 wt %. In C₁₂OOH–MMT, the maximum enhancement of the ultimate tensile strength and the initial modulus for the nanocomposites was observed for blends containing 6 wt % organoclay. Na ion‐exchanged clays have higher tensile strengths than those of organic alkyl‐exchanged clays in PVA nanocomposites films. On the other hand, organic alkyl‐exchanged clays have initial moduli that are better than those of Na ion‐exchanged clays. Overall, the content of clay particles in the polymer matrix affect both the thermal stability and the tensile properties of the polymer/clay nanocomposites. However, a change in thermal stability with clay was not significant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3208–3214, 2003     

Blended Epoxy/Polyester Polymer Nanocomposites: Effect of “Nano” on Mechanical Properties

The inter-cross-linked networks of unsaturated polyester (UP) toughened epoxy blends were developed. Montmorillonite (MMT) clay was dispersed into the same system to prepare blended epoxy/UP/clay nanocomposites in different weight ratios viz. 0%, 1%, 2%, 3% and 5%. Mechanical properties like tensile strength (TS), impact strength (IS) and interlaminar shear strength (ILSS) were characterized for the above nanocomposites. Blended nanocomposites were fabricated by high shear mechanical mixing followed by ultra-sonication process to get homogeneous mixing under the aid of in situ polymerization. Mechanical properties were studied as per ASTM standards. Data obtained from mechanical property studies indicated that the introduction of UP into epoxy resin improved the impact strength to an appreciable extent. Impact strength (IS) and tensile strength (TS) were significantly improved and optimized at 3 wt. % clay content when compared with neat blend (0 wt. % clay) composites. The homogeneous morphologies of the UP toughened epoxy and epoxy/UP/clay nanocomposite systems were ascertained using scanning electron microscope (SEM) studies.     

Mechanical,thermal, and barrier properties of nanocomposites based on poly(butylene succinate)/thermoplastic starch blends containing different types of clay

Nanocomposites based on blends of poly(butylene succinate) (PBS) and thermoplastic cassava starch (TPS) were prepared using a two‐roll mill and compression molding, respectively. Two different types of clay, namely sodium montmorillonite (CloisiteNa) and the organo‐modified MMT (Cloisite30B) were used. The morphological and mechanical properties of the nanocomposite materials were determined by using XRD technique and a tensile test, respectively. Thermal properties of the composite were also examined by dynamic mechanical thermal analysis and thermal gravimetric techniques. Barrier properties of the nanocomposites were determined using oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) tests. From the results, it was found that by adding 5 pph of the clay, the tensile modulus and the thermal properties of the blend containing high TPS (75 wt %) changed significantly. The effects were also dependent on the type of clay used. The use of Cloisite30B led to a nanocomposite with a higher tensile modulus value, whereas the use of CloisiteNa slightly enhanced the thermal stability of the material. OTR and WVTR values of the blend composites containing high PBS ratio (75 wt %) also decreased when compared to those of the neat PBS/TPS blend. XRD patterns of the nanocomposites suggested some intercalation and exfoliation of the clays in the polymer matrix. The above effects are discussed in the light of different interaction between clays and the polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1114‐1123, 2013     

Effects of ultrasound on the synthesis and properties of polyurethane foam/clay nanocomposites

Polyurethane foam (PUF)/clay nanocomposites were synthesized with clay modified by polymeric 4,4′‐diphenylmethane diisocyanate (PMDI) with the application of ultrasound. Transmission electron micrographs showed that the interlayer distance increased for the polyurethane (PU)/clay nanocomposites where ultrasound was applied. The results of the transmission electron microscopy and X‐ray measurements suggest that the application of ultrasound to the clay modification with PMDI improved the efficiency of the clay modification by the effective breakup of the clay agglomerates and intercalation of the silicate layers. In the mechanical tests of the PUF/clay nanocomposites, the flexural and tensile strengths of the PUF/clay nanocomposites showed the maximum value at 3.0 wt % clay content based on PMDI. These results suggest that the increases in the flexural and tensile strengths were perhaps due to the uniform dispersion of the clay by the application of ultrasound. At the same modified clay content, the fire resistance properties were increased for the PUF/clay nanocomposites with the application of ultrasound compared to the PUF/clay nanocomposites without the application of ultrasound. The cell size and thermal conductivity were decreased for the PUF/clay nanocomposites with the application of ultrasound compared to the PUF/clay nanocomposite without the application of ultrasound. Because of these results, we suggest that the smaller cell size and lower thermal conductivity of the PUF/clay nanocomposites were mainly due to the enhanced dispersion of the clay by the application of ultrasound to the mixture of PMDI and clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3764–3773, 2006     

Reaction kinetics and characteristics of polyurethane/clay nanocomposites

The reaction behavior and physical properties of polyurethane (PU)/clay nanocomposite systems were investigated. Organically modified clay was used as nanofillers to formulate the nanocomposites. Differential scanning calorimetry was used to study the reaction behavior of the PU/clay nanocomposite systems. The reaction rate of the nanocomposite systems increased with increasing clay content. The reaction kinetic parameters of proposed kinetic equations were determined by numerical methods. The glass transition temperatures of the PU/clay nanocomposite systems increased with increasing clay content. The thermal decomposition behavior of the PU/clay nanocomposites was measured by using thermogravimetric analysis. X‐ray diffractometer and transmission electronic microscope data showed the intercalation of PU resin between the silicate layers of the clay in the PU/clay nanocomposites. A universal testing machine was used to investigate the tensile properties of the PU/clay nanocomposites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1641–1647, 2005     

Synthesis and characterization of epoxy based nanocomposites

Epoxy‐clay nanocomposites were synthesized to examine the effects of the content and type of different clays on the structure and mechanical properties of the nanocomposites. Diglycidyl ether of bisphenol‐A (epoxy) was reinforced by 0.5–11 wt % natural (Cloisite Na⁺) and organically modified (Cloisite 30B) types of montmorillonite. SEM results showed that as the clay content increased, larger agglomerates of clay were present. Nanocomposites with Cloisite 30B exhibited better dispersion and a lower degree of agglomeration than nanocomposites with Cloisite Na⁺. X‐ray results indicated that in nanocomposites with 3 wt % Cloisite 30B, d‐spacing expanded from 18.4 Å (the initial value of the pure clay) to 38.2 Å. The glass transition temperature increased from 73°C, in the unfilled epoxy resin, to 83.5°C in the nanocomposite with 9 wt % Cloisite 30B. The tensile strength exhibited a maximum at 1 wt % modified clay loading. Addition of 0.5 wt % organically modified clay improved the impact strength of the epoxy resin by 137%; in contrast, addition of 0.5 wt % unmodified clay improved the impact strength by 72%. Tensile modulus increased with increasing clay loading in both types of nanocomposites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1081–1086, 2005     

Properties of Waterborne Polyurethane/Clay Nanocomposite Adhesives

A series of waterborne polyurethane (WBPU)/clay nanocomposite dispersions using two different organically modified clays, namely Cloisite 15A and Cloisite 30B, were prepared. It was found that the properties of WBPU/clay nanocomposites were highly dependent on both the clay content and the clay surface characteristic (hydrophilic/hydrophobic). A WBPU/clay nanocomposite dispersion with a higher clay content showed a less negative zeta potential. A lower zeta potential for dispersion with Cloisite 30B compared to Cloisite 15A was observed indicating a higher stability of the dispersion. The tensile strength, Young's modulus and adhesive strength of WBPU/clay nanocomposite containing Cloisite 30B were also higher than those of nanocomposite containing Cloisite 15A. The optimum clay contents, with respect to these properties, for nanocomposites with Cloisite 15A and Cloisite 30B were found to be 2 wt% and 3 wt%, respectively.     

Effects of graphene nanosheets on the dielectric,mechanical, thermal properties,and rheological behaviors of poly(arylene ether nitriles)

Poly(arylene ether nitriles) (PEN) containing various contents of graphene nanosheets (GNs) was prepared via solution‐casting method and investigated for their dielectric, mechanical, thermal, and rheological properties. For PEN/GNs nanocomposite with 5 wt % GNs, the dielectric constant was increased to 9.0 compared with that of neat PEN (3.1) and dielectric losses of all nanocomposites were in the range of 0.019–0.023 at 1 kHz. The tensile modulus and strength were increased about 6 and 14% with 0.5% GNs, respectively. The fracture surfaces of the all PEN/GNs nanocomposites revealed that GNs had good adhesion to PEN matrix. The thermal properties of the nanocomposites showed significant increase with increasing GN loading. For 5 wt % GNs‐reinforced PEN nanocomposite, the temperatures corresponding to a weight loss of 5 wt % (T_d5%) and 30 wt % (T_d30%) increased by about 20 and 13°C, respectively. Rheological properties of the PEN nanocomposites showed a sudden change with the GN fraction and the percolation threshold was about 1 wt % of GNs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of organic vermiculite/polymethylmethacrylate nanocomposite featuring excellent mechanical and thermal properties via ultrasonic in situ polymerisation

To improve the dispersion of organically modified vermiculite (OVMT) in polymethylmethacrylate (PMMA), the method of ultrasonic in situ polymerization was introduced, and a series of OVMT/PMMA nanocomposites were successfully prepared. The structure, morphology, and mechanical and thermal properties of as-prepared sample had been investigated. Results showed that the assistance of ultrasonic irradiation could be beneficial for the good homogeneous dispersion and strong interfacial interaction of OVMT in PMMA. Consequently, the obtained nanocomposites showed better mechanical and thermal properties than those prepared without the assistance of ultrasonic irradiation. When the OVMT content was 3 wt.%, the nanocomposite prepared by ultrasonic in situ polymerization exhibited the Young's modulus, tensile strength, elongation at break and degradation temperatures for 5% and 50% weight loss of 1177 MPa, 65 MPa, 14%, 219.82ºC and 373.91ºC, respectively. These results suggested the great potential application of ultrasonic in situ polymerization for the synthesis of polymer/clay nanocomposite.     

Nanocomposites based on poly(butylene adipate‐co‐terephthalate) and montmorillonite

Nanocomposites based on biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) and layered silicates were prepared by the melt intercalation method. Nonmodified montmorillonite (MMT) and organo‐modified MMTs (DA‐M, ODA‐M, and LEA‐M) by the protonated ammonium cations of dodecylamine, octadecylamine, and N‐lauryldiethanolamine, respectively, were used as the layered silicates. The comparison of interlayer spacing between clay and PBAT composites with inorganic content 3 wt % measured by X‐ray diffraction (XRD) revealed the formation of intercalated nanocomposites in DA‐M and LEA‐M. In case of PBAT/ODA‐M (3 wt %), no clear peak related to interlayer spacing was observed. From morphological studies using transmission electron microscopy, the ODA‐M was found to be finely and homogeneously dispersed in the matrix polymer, indicating the formation of exfoliated nanocomposite. When ODA‐M content was increased, the XRD peak related to intercalated clay increased. Although the exfoliated ODA‐M (3 wt %) nanocomposite showed a lower tensile modulus than the intercalated DA‐M and LEA‐M (3 wt %) composites, the PBAT/ODA‐M composite with inorganic content 5 wt % showed the highest tensile modulus, strength, and elongation at break among the PBAT composites with inorganic content 5 wt %. Their tensile properties are discussed in relation to the degree of crystallinity of the injection molded samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 386–392, 2005     

Investigation on the Mechanical and Thermal Properties of Intercalated Epoxy/Layered Silicate Nanocomposites

Epoxy resin/layered silicate nanocomposites with various clay contents were prepared. The structural studies showed the intercalation of epoxy polymer chains into the clay galleries. The adhesion analysis of nanocomposite coating films on metallic substrates showed the excellent adhesion of epoxy-based nanocomposite coatings on iron plates, especially in lower clay loadings. According to the hardness test results, the organoclay minerals caused the increasing of the hardness of epoxy nanocomposites. The thermal properties of nanocomposites were evaluated by means of DSC and TGA analysis. The tensile and compression strengths of cured epoxy/clay systems were also investigated.     

Effect of clay on mechanical and gas barrier properties of blown film LDPE/clay nanocomposites

Low density polyethylene (LDPE)/clay nanocomposites, which can be used in packaging industries, were prepared by melt‐mix organoclay with polymer matrix (LDPE) and compatibilizer, polyethylene grafted maleic anhydride (PEMA). The pristine clay was first modified with alkylammonium salt surfactant, before melt‐mixed in twin screw extruder attached to blown‐film set. D‐spacing of clay and thermal behavior of nanocomposites were characterized by Wide‐Angle X‐ray Diffraction (WAXD) and differential scanning calorimetry (DSC), respectively. WAXD pattern confirmed the increase in PEMA contents exhibited better dispersion of clay in nanocomposites. Moreover, DSC was reported the increased PEMA contents caused the decrease in degree of crystallinity. Mechanical properties of blown film specimens were tested in two directions of tensile tests: in transverse tests (TD tests) and in machine direction tests (MD tests). Tensile modulus and tensile strength at yield were improved when clay contents increased because of the reinforcing behavior of clay on both TD and MD tests. Tensile modulus of 7 wt % of clay in nanocomposite was 100% increasing from neat LDPE in TD tests and 17% increasing in MD tests. However, elongation at yield decreased when increased in clay loading. Oxygen permeability tests of LDPE/clay nanocomposites also decreased by 24% as the clay content increased to 7 wt %. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

An investigation of melt rheology and thermal stability of poly(lactic acid)/ poly(butylene succinate) nanocomposites

A systematic investigation of the rheological and thermal properties of nanocomposites prepared with poly(lactic acid) (PLA), poly(butylene succinate) (PBS), and organically modified layered silicate was carried out. PLA/PBS/Cloisite 30BX (organically modified MMT) clay nanocomposites were prepared by using simple melt extrusion process. Composition of PLA and PBS polymers were fixed at a ratio of 80 to 20 by wt % for all the nanocomposites. Rheological investigations showed that high clay (> 3 wt %) contents strongly improved the viscoelastic behavior of the nanocomposites. Percolation threshold region was attained between 3 and 5 wt % of clay loadings. With the addition of clay content for these nanocomposites, liquid‐like behavior of PLA/PBS blend gradually changed to solid‐like behavior as shown by dynamic rheology. Steady shear showed that shear viscosity for the nanocomposites decreased with increasing shear rates, exhibiting shear‐thinning non‐Newtonian behavior. At higher clay concentrations, pseudo‐plastic behavior was dominant, whereas pure blend showed almost Newtonian behavior. Thermogravimetric analysis revealed that both initial degradation temperature (at a 2% weight loss) and activation energy of thermal decomposition nanocomposite containing 3 wt % of C30BX were superior to those of other nanocomposites as well as to those of PLA/PBS blend. Nanocomposite having 1 wt % of C30BX did not achieve expected level of thermal stability due to the thermal instability of the surfactant present in the organoclay. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Application of the taguchi approach to investigate the effects of clay content and saponification parameters on the tensile properties of poly(vinyl alcohol)/clay nanocomposites

Poly(vinyl alcohol) (PVA)/montmorillonite nanocomposites were prepared via solution polymerization. The nanocomposites were formed either by first hydrolyzing poly(vinyl acetate) (PVAc) to PVA and then preparing the PVA/clay, or by initially preparing PVAc/clay and then hydrolyzing the matrix to PVA. The morphology of the nanocomposites was examined by X‐ray diffraction and transmission electron microscopy, which suggested the proper dispersion of silicate layers within the PVA matrix. The influences of some variables including method of preparation, clay content, and time and temperature of saponification on the tensile properties (elastic modulus, stress and elongation at break) of the nanocomposite samples were investigated by using the Taguchi experimental design approach. The results indicated that the tensile properties of the nanocomposites improved as clay content, and the temperature and time of saponification increased. Effect of each factor on the ultimate properties of as prepared nanocomposites are discussed in detail. The analysis of variance (ANOVA) showed that the method of preparation did not influence the ultimate tensile properties of the nanocomposite samples. Thermal degradation of the nanocomposites was studied by thermogravimetric analysis, which showed that their thermal stability was higher than that of virgin polymer. J. VINYL ADDIT. TECHNOL., 19:276–284, 2013. © 2013 Society of Plastics Engineers     

Morphology and properties of PVC/clay nanocomposites via in situ emulsion polymerization

PVC/Na⁺–montmorillonite (MMT) nanocomposites were prepared via a simple technique of emulsion polymerization at several different MMT clay concentrations. X‐ray diffraction and transmission electron microscopy studies revealed the formation of a mixture of intercalated and exfoliated nanostructure. Tensile testing results showed that the tensile modulus of the nanocomposites increased with the addition of clay, while the tensile strength decreased little. The notched impact strength of the nanocomposites was also improved. For systems containing clay in the range of 2.1 to 3.5 wt %, the impact strength was almost two times as large as that of pure PVC. However, those mechanical properties began to decrease with the continuously increasing amount of clay. The fracture surface of pure PVC and the nanocomposites was observed by scanning electron microscope. Thermal properties of the nanocomposites were found to increase as a result of clay incorporation. The glass transition temperatures of the PVC/clay nanocomposites were nearly identical to that of pure PVC. The Vicat softening points exhibited a progressively increasing trend with the clay content added. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 277–286, 2004     

Comparative effect of metallocene and Ziegler‐Natta polypropylene on the exfoliation of montmorillonite and hectorite clays to obtain nanocomposites

The present study was carried out on the effect of molecular weight and polydispersity of polypropylene (PP) obtained via Ziegler‐Natta or metallocene catalysis on the formation of nanocomposites with montmorillonite and mineral and synthetic hectorite. The formation of the nanocomposites was achieved by the melt‐mix method. X‐ray diffraction, transmission electron microscopy, and analysis of mechanical properties showed that, using PP obtained via metallocene catalysis (polydispersity ～ 2), it is possible to achieve improved formation of nanocomposites compared with PP obtained via Ziegler‐Natta catalysis (polydispersity ～ 4). It was also found that the molecular weight of the PP affects the tendency toward clay exfoliation and consequently the properties of the nanocomposites. Montmorillonite type clay was evaluated at 1%, 3%, and 5% by weight in the nanocomposite. The nanocomposite with 1 wt % clay was found to have better mechanical properties compared with the nanocomposite containing 3 wt % and 5 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 698–706, 2007     

Influence of processing condition and carbon nanotube on mechanical properties of injection molded multi‐walled carbon nanotube/poly(methyl methacrylate) nanocomposites

In this work, multi‐walled carbon nanotubes (MWCNT) and poly(methyl methacrylate) (PMMA) pellets were compounded via corotating twin‐screw extruder. The produced MWCNT/PMMA nanocomposite pellets were injection molded. The effect of MWCNT concentration, injection melt temperature and holding pressure on mechanical properties of the nanocomposites were investigated. To examine the mechanical properties of the MWCNT/PMMA nanocomposites, tensile test, charpy impact test, and Rockwell hardness are considered as the outputs. Design of experiments (DoE) is done by full factorial method. The morphology of the nanocomposites was performed using scanning electron microscopy (SEM). The results revealed when MWCNT concentration are increased from 0 to 1.5 wt %, tensile strength and elongation at break were reduced about 30 and 40%, respectively, but a slight increase in hardness was observed. In addition, highest impact strength belongs to the nanocomposite with 1 wt % MWCNT. This study also shows that processing condition significantly influence on mechanical behavior of the injection molded nanocomposite. In maximum holding pressure (100 bar), the nanocomposites show highest tensile strength, elongation, impact strength and hardness. According to findings, melt temperature has a trifle effect on elongation, but it has a remarkable influence on tensile strength. In the case of impact strength, higher melt temperature is favorable. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43738.     

Fracture behavior of thermoplastic polyolefin/clay nanocomposites

A thermoplastic polyolefin (TPO) containing 70 wt % styrene–ethylene–butadiene‐styrene‐g‐maleic anhydride and 30 wt % polypropylene and its nanocomposites reinforced with 0.3–1.5 wt % organoclay were prepared by melt mixing followed by injection molding. The mechanical and fracture behaviors of the TPO/clay nanocomposites were investigated. The essential work of fracture (EWF) approach was used to evaluate the tensile fracture behavior of the nanocomposites toughened with elastomer. Tensile tests showed that the stiffness and tensile strength of TPO was enhanced by the addition of low loading levels of organically modified montmorillonite. EWF measurements revealed that the fracture toughness of the TPO/clay nanocomposites increased with increasing clay content. The organoclay toughened the TPO matrix of the nanocomposites effectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008