Biodegradable nanocomposites from maleated polycaprolactone/soy protein isolate blend with organoclay: Preparation,characterization, and properties

New biobased, eco-friendly nanocomposites were prepared from maleated polycaprolactone/soy protein isolate blend (50/50 wt/wt) with organo-modified clay by melt compounding. The XRD, TEM, tensile, DMTA, and rheological properties of the nanocomposites were investigated. X-ray diffraction and transmission electron microscopy analysis revealed that the intercalated nanocomposite is formed and the silicate layers of the clay are uniformly dispersed at a nanometer scale in the polymer matrix. There is a great enhancement in tensile and dynamic mechanical properties of the nanocomposites. Rheological study revealed that the nanocomposite exhibits strong shear thinning behavior and clay particles form network in the melted state of the composites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Preparation, mechanical and rheological properties of a thermoplastic polyolefin (TPO)/organoclay nanocomposite with reference to the effect of maleic anhydride modified polypropylene as a compatibilizer

A thermoplastic polyolefin (TPO)/organoclay nanocomposite has been successfully prepared by using maleic anhydride modified polypropylene as a compatibilizer. The nanocomposite was characterized by IR spectra, X-ray diffraction and Transmission Electron Microscope. The nanocomposite exhibited remarkable improvement of tensile and storage modulus over its pristine counterpart. Enhancement of storage modulus (in melted state) and decrease in terminal slope of the nanocomposite (over its pristine equivalent in the frequency sweep experiment) confirms the fact that a strong interaction exists between clay platelet and polymer molecules in the melted state. For both the nanocomposite and its pristine counterpart, strong shear thinning behavior was observed in the melted state (as examined by frequency sweep experiment).     

Effects of silane grafting on the morphology and thermal stability of poly(ethylene terephthalate)/clay nanocomposites

An alkylammonium intercalated montmorillonite (A‐MMT) was modified by edge grafting with 3‐glycidoxypropyltrimethoxysilane. In comparison with poly(ethylene terephthalate) (PET)/A‐MMT, the resultant grafted clay, S‐A‐MMT, exhibited improved miscibility with PET matrix and revealed better dispersion state in the melting compounded PET/S‐A‐MMT nanocomposites. As a result, the PET/S‐A‐MMT nanocomposite had slower degradation rate owing to the enhanced clay barrier effect. Meanwhile, the nanocomposite exhibited lower degradation onset temperature under nitrogen because of the clay catalysis effect, which can be explained by the decreasing degradation reaction energy calculated from Coats–Redfern method of degradation kinetics. In the other hand, nanocomposite with better clay dispersion state exhibited increasing thermal oxidative stability due to clay barrier effect of hindering oxygen to diffuse in, which accorded with the continuous and compact char surface formed during polymer degradation. The clay catalysis and barrier effect of silicate layers were presented directly in isothermal oxidative TGA experiment. Furthermore, the mechanical and crystallization properties of PET/clay nanocomposites were investigated as well. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Intercalation behavior of hydroxylated dendritic polyesters in polymer clay nanocomposites prepared from aqueous solution

Second and fourth generations of hydroxylated dendritic polyesters based on 2,2-bis-methylopropionic acid (bis-MPA) with an ethoxylated pentaerytriol (PP50) core were combined with unmodified sodium montmorillonite clay (Na⁺MMT) in water to generate a broad range of polymer clay nanocomposite films from 0 to 100% wt/wt. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. Intercalation was the dominant state in these nanocomposites. Significant exfoliation was only observed within 0–5% wt/wt of mineral composition range. It was shown that interlayer spacing changed within the composition range 5–95% wt/wt from 0.5 nm to up to 3.5 nm in a step-like fashion with 0.5 nm increments which corresponded to a flattened conformation of confined hyperbranched polymers (HBP). Second and fourth generations exhibited the same layer-by-layer intercalation of completely flattened HBPs. No dependence of interlayer spacings on generation number was found. XRD and TEM revealed the presence of mixed intercalated populations with interlayer spacings at multiples of 0.5 nm.     

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     

Preparation and barrier property of poly(ethylene terephthalate)/clay nanocomposite using clay‐supported catalyst

Poly(ethylene terephthalate) (PET)/clay nanocomposite was prepared by the direct polymerization with clay‐supported catalyst. The reaction degree of catalyst against the cation exchange capacity of clay was 8 wt %. The intercalation of PET chains into the silicate layers was revealed by X‐ray diffraction studies. SEM morphology of the nanocomposite showed a good dispersion of clay‐supported catalyst, ranging from 30 to 100 nm. The intercalated and exfoliated clay‐supported catalyst in PET matrix was also observed by TEM. The improvement of O₂ permeability for PET/clay‐supported catalyst composite films over the pure PET is approximately factors of 11.3–15.6. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4875–4879, 2006     

Physical and dyeing properties of poly(ethylene terephthalate)/montmorillonite nanocomposite filament yarns

This research paper describes the generation of poly(ethylene terephthalate) (PET)/organoclay nanocomposite filaments by melt‐spinning method and investigation of their physical and dyeing properties. Two montmorillonite types of clay were modified using an intercalating agent synthesized and PET/organoclay (85/15 wt/wt) master batches were prepared using a corotating intermeshing twin screw extruder. Afterward, nanocomposite filaments containing different amounts of organoclay (0.5–5 wt%) were produced and dyed with two disperse dyes at atmospheric and high temperature dyeing conditions. Increased clay concentration led to reduced mechanical properties. Nonetheless, PET/organoclay nanocomposite filaments showed enhanced dyeability. POLYM. ENG. SCI., 2013. © Society of Plastics Engineers     

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     

Positive‐working aqueous base developable photosensitive polybenzoxazole precursor/organoclay nanocomposites

Positive‐working aqueous base developable photosensitive polybenzoxazole (PBO) precursor/organoclay nanocomposites have been prepared through the addition of an organoclay to a PBO precursor. The organoclay was formed by a cation exchange reaction between a Na⁺‐montmorillonite clay and an ammonium salt of dodecylamine. The PBO precursor used in this study was a polyhydroxyamide that was prepared from a low‐temperature polymerization of 2′2′‐bis(3‐amino‐4‐hydroxyphenyl) hexafluoropropane and 4,4′‐oxydibenzoyl chloride with an inherent viscosity of 0.3 dL/g. The photosensitive resin/clay formulations were prepared from the precursor with 2,3,4‐tris(1‐oxo‐2‐diazonaphthoquinone‐5‐sulfonyloxy)‐benzophenone photosensitive compound and 3–5 wt % organoclay. The PBO precursor/clay was subsequently thermally cured to PBO/clay at 350°C. Both X‐ray diffraction and transmission electron microscope analyses showed that the organoclay was dispersed in the PBO matrix in a nanometer scale. The thermal expansion coefficient of PBO/clay film, which contained 5 wt % organoclay, was decreased 33% compared to the pure PBO film. The PBO/clay nanocomposite films also displayed higher thermal stability, glass transition temperature, and water resistance than the pure PBO film. The photosensitive PBO precursor/clay nanocomposite showed a line/space pattern with a resolution of 5 μm and its sensitivity and contrast were not affected by the organoclay. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2350–2356, 2005     

Nanoencapsulation of montmorillonite clay within poly(ethylene glycol) nanobeads by electrospraying

The present study describes the preparation and characterization of a novel nanocomposite, based on montmorillonite clay (MMT) encapsulation in poly(ethylene glycol) (PEG) by an electrospraying process. PEG/MMT nanocomposites with MMT contents ranging from 1 to 5 wt % were successfully prepared and characterized in relation to their morphological, spectroscopic, structural, and thermal properties. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy micrographs showed that the PEG nanobeads formed spherical shapes, and with increasing amount of MMT clay, the size of the beads decreased significantly, ranging from 120 to 3.7 nm. The Fourier transform infrared spectroscopy results suggested that there was no significant chemical interaction between PEG and MMT clay. However, the d‐spacing of MMT clay in PEG/MMT increased, a clear indication of the intercalation of PEG in the interlayer spaces of MMT clay. Furthermore, the thermal stability of PEG polymer decreased upon encapsulation of MMT clay in PEG/MMT composites. Nanoindentation results showed that the hardness and Young's modulus of the PEG/MMT composites increased with 3 wt % loading of MMT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45048.     

Characterization of structure and corrosion resistivity of polyurethane/organoclay nanocomposite coatings prepared through an ultrasonication assisted process

In this study, a series of castor oil based polyurethane/organically modified montmorillonite (OMMT) clay nanocomposite coatings have been successfully prepared by effective dispersing of OMMT nano-layers in polyurethane matrix through an ultrasonication assisted process. Effectiveness of ultrasonication process in de-agglomeration of clay stacks in castor oil dispersions was evaluated by optical microscopy and sedimentation test. Structure of nanocomposite coatings was investigated by wide angle X-ray diffraction (WAXD) and Fourier-transform infrared spectroscopy (FT-IR). The anticorrosive properties of nanocomposite coatings were characterized by electrochemical impedance spectroscopy (EIS), Tafel polarization study, water absorption and pull-off adhesion tests. The experimental results showed that PU/OMMT nanocomposite coatings were superior to the neat PU in corrosion protection effects. Also, it was observed that the corrosion protection of polyurethane organoclay nanocomposite coatings is improved as the clay loading is increased up to 3 wt.%.     

Investigation of the corrosion protection behavior of natural montmorillonite clay/bitumen nanocomposite coatings

The influence of clay particles on the corrosion properties of bituminous coating was studied. Different percentages of natural montmorillonite clay (Cloisite Na⁺) were added to emulsified bitumen in water to make 2 wt.%, 3 wt.% and 4 wt.% of clay/bitumen nanocomposite coatings. The coatings were applied on steel 37. Optical microscopy and transmission electron microscopy (TEM) were employed to study the structure of nanocomposite. To investigate the anti-corrosion properties of the coated panels, electrochemical impedance spectroscopy (EIS) was used. The findings indicated that the addition of clay nanolayers improved corrosion resistance of the coatings. Moreover, increasing clay loading up to 4 wt.%, increased the corrosion resistance.     

Thermal,mechanical, and gas barrier properties of ethylene–vinyl alcohol copolymer‐based nanocomposites for food packaging films: Effects of nanoclay loading

For the application of single‐layer food packaging films with improved barrier properties, an attempt was made to prepare ethylene‐vinyl alcohol (EVOH) copolymer‐based nanocomposite films by incorporation of organically modified montmorillonite nanoclays via a two‐step mixing process and solvent cast method. The highly intercalated tactoids coexisted with exfoliated clay nanosheets, and the extent of intercalation and exfoliation depended significantly on the level of clay loadings, which were confirmed from both XRD measurements and TEM observations. It was revealed that the inclusion of nanoclay up to an appropriate level of content resulted in a remarkable enhancement in the thermal, mechanical (tensile strength/modulus), optical, and barrier properties of the prepared EVOH/clay nanocomposite films. However, excess clay loadings gave rise to a reduction in the tensile properties (strength/modulus/elongation) and optical transparency due to the formation of clay tactoids with a larger domain size. With the addition of only 3 wt % clay, the oxygen and water vapor barrier performances of the nanocomposite films were substantially improved by 59 and 90%, respectively, compared to the performances of the neat EVOH film. In addition, the presence of clay nanosheets in the EVOH matrix was found to significantly suppress the moisture‐derived deterioration in the oxygen barrier performance, implying the feasibility of applying the nanocomposite films to single‐layer food packaging films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40289.     

Morphology,deformation behavior and thermomechanical properties of polypropylene/maleic anhydride grafted polypropylene/layered silicate nanocomposites

Nanocomposites polypropylene (PP) with 3 and 7 wt % of clay were prepared by melt mixing. Four types of maleic anhydride grafted PP (MAPP) in broad range of MA groups content (0.3–4 wt %) and molecular weights (MW) were used as polar compatibilizers. The effect of the MAPP kind on both the clay dispersion and miscibility with PP was studied. The mixed intercalated/exfoliated morphologies of nanocomposites in the presence of all studied compatibilizers were revealed by XRD and TEM. The oligomer compatibilizer with 4 wt % of MA groups increases the intercalation ability of polymer into clay galleries but this one has limited miscibility with PP and worsens crystalline structure of polymer matrix. The MAPPs with 0.3–1.3% of MA are characterized by the lower intercalation ability but well cocrystallize with PP. Maximum reinforcing effect is attained using high MW MAPP with 0.6% MA and for nanocomposite with 7 wt % (3.8 vol %) of clay it averages almost 1.7 times relative to neat PP and 1.3 times relative to noncompatibilized composite. Dynamic storage moduli of nanocomposites compatibilized by MAPPs with 0.3–1.3% of MA containing 7 wt % of clay increase up to 1.4–1.5 around 30–75°C and over the whole temperature range remain higher compared with both neat PP and uncompatibilized composite. On the contrary, the oligomer MAPP with 4 wt % of MA groups decreases the thermal–mechanical stability of nanocomposite at high temperature compared with both PP and uncompatibilized composites. The study of nanocomposites flammability showed that creating complex composites containing both layered silicate and relatively small amount of magnesium hydroxide can be a successful approach to reduce the combustibility of PP‐based nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Mechanical properties of the flexible‐type epoxy/clay nanocomposites prepared by slurry method

The bisphenol‐F type flexible epoxy resin, having a good flexibility, was combined with an organo‐ and slurry‐clay. The clay dispersions in the obtained epoxy/clay systems are significantly different depending on the type of clay. Particularly, the epoxy/slurry‐clay system showed a high clay dispersibility into the epoxy matrix and was transparent in spite of the addition of 10 wt % clay. This result means that the swelling of the clay with formamide is effective for the expansion of the basal spacing of the clay. The slurry‐clay nanocomposite (clay content: 5 wt %) showed a 4 times higher fracture energy than the neat epoxy system in the tensile test, though the organo‐clay system (clay content: 5 wt %) was 1.5 times higher. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Dehydration of water–alcohol mixtures by vapor permeation through PVA/clay nanocomposite membrane

An organic/inorganic hybrid nanocomposite membrane, poly(vinyl alcohol)/clay (PVAC), was prepared. The morphology of PVAC nanocomposite membranes were characterized using transmission electron microscopy (TEM), X‐ray diffraction (XRD), and atomic force microscopy (AFM). The crystallinity and surface roughness increases with an increasing clay content in the PVAC nanocomposite membrane. Compared with the pure poly(vinyl alcohol) (PVA) membrane, the hybrid nanocomposite membrane (PVAC) shows an improvement in the thermal stability and the prevention of the water‐soluble property. The oxygen permeability and the water‐vapor permeation rate decreases with an increasing clay content (1–3 wt %) in the PVAC nanocomposite membranes. In addition, the effects of the clay content on the vapor‐permeation performance of an aqueous ethanol solution through the PVAC nanocomposite membranes was also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3632–3638, 2003     

Preparation of polyethylene‐octene elastomer/clay nanocomposite and microcellular foam processed in supercritical carbon dioxide

Polyethylene‐octene elastomer (POE)/organoclay nanocomposite was prepared by melt mixing of the POE with an organoclay (Cloisite 20A) in an internal mixer, using poly[ethylene‐co‐(methyl acrylate)‐co‐(glycidyl methacrylate)] copolymer (E‐MG‐GMA) as a compatibilizer. 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 nanometre scale in the POE matrix. The nanocomposite exhibited greatly enhanced tensile and dynamic mechanical properties compared with the POE/clay composite without the compatibilizer. The POE/E‐MA‐GMA/clay nanocomposite was used to produce foams by a batch process in an autoclave, with supercritical carbon dioxide as a foaming agent. The nanocomposite produced a microcellular foam with average cell size as small as 3.4 µm and cell density as high as 2 × 10¹¹ cells cm^?3. Copyright © 2005 Society of Chemical Industry     

Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO₄ electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO₄, heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 × 10⁻⁴ S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO₄ electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications.     

Study of the effect of organic clay on the shear‐induced crystallization of high‐density polyethylene through dynamic‐packing injection molding

Organic nanoparticles as heterogeneous nucleators have a great effect on the crystallization of polymer matrices in nanocomposite systems, and the effect will be enhanced under shear flow. A home‐made dynamic‐packing injection molding (DPIM) device was developed to explore the effect of organic clay on the shear‐induced crystallization of high‐density polyethylene (HDPE). Differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD) and scanning electron microscopy (SEM) were used to characterize the flow‐induced crystalline structure of HDPE/clay nanocomposite injection moldings. It was found that higher crystallinity and thicker crystal planes which contribute to the improvement of mechanical properties were achieved in HDPE/clay nanocomposite samples prepared by DPIM. DSC results clearly showed that an increase of about 16% in crystallinity was achieved in dynamic HDPE/clay nanocomposite samples compared with traditional unfilled HDPE samples. WAXD confirmed that dynamic HDPE/clay nanocomposite samples had maximum crystal sizes at the (110) and (200) planes of 335 and 305 Å, respectively. SEM images indicated that the arrangement of crystalline structures in dynamic HDPE/clay samples was altered slightly compared with unfilled HDPE samples prepared using the same processing parameters. The results showed that organic clay was beneficial for increasing crystallinity and crystal size in the HDPE/clay nanocomposite system under shear flow. Meanwhile the arrangement of crystalline structures was insignificantly affected by the organic clay, and the preferred regular arrangement of lamellae could still be formed in the dynamic HDPE/clay nanocomposite system. Copyright © 2010 Society of Chemical Industry     

Preparation and characterization of rubber‐toughened poly(trimethylene terephthalate)/organoclay nanocomposite

Rubber‐toughened poly(trimethylene terephthalate) (PTT)–organoclay nanocomposite (RTPTTCN) was prepared by a melt mixing technique. The rubber‐toughened PTT (RTPTT) was made by blending it with ethylene propylene diene terpolymer (EPDM) and with a small amount of maleated EPDM as a compatibilizer. XRD and TEM analysis indicated that the RTPTTCN forms a partially exfoliated nanocomposite. It was observed from SEM analysis that the clay nanoparticles induced a reduction of rubber particle size in the PTT matrix. Tensile and dynamic mechanical analysis indicated that the clay nanoparticles enhance the stiffness of the RTPTT without adversely affecting its toughness. Melt rheological studies revealed that the nanocomposites exhibited strong shear thinning behavior, and a percolated network of the clay particles was formed. It was also observed from DSC that the clay nanoparticles caused an increase in the nonisothermal crystallization temperature of the PTT. POLYM. ENG. SCI., 47:863–870, 2007. © 2007 Society of Plastics Engineers