Synthesis and characterization of polyethylene‐octene elastomer/clay/biodegradable starch nanocomposites

The aim of this work is the production of new nanocomposites from metallocene polyethylene‐octene elastomer (POE), montmorillonite and biodegradable starch by means of a melt blending method. Characterizations of clay, modified clay, POE, POE‐g‐AA, and the hybrids produced from polymer, clay, and/or starch were performed by X‐ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectrophotometer, differential scanning calorimetry (DSC), thermogravimetry analyzer (TGA), scanning electron microscope (SEM), and Instron mechanical tester. As to the results, organophilic clay can be well dispersed into acrylic acid grafted polyethylene‐octene elastomer (POE‐g‐AA) in nanoscale sizes since cetyl pyridium chloride is partially compatible with POE‐g‐AA and allows POE‐g‐AA chains to intercalate into clay layers. Based on consideration of thermal and mechanical properties, it is also found that 12 wt % of clay content is optimal for preparation of POE‐g‐AA/clay nanocomposites. The new partly biodegradable POE‐g‐AA/clay/starch hybrid could obviously improve the elongation and the tensile strength at break of the POE‐g‐AA/starch hybrid since the former can give the smaller starch phase size and nanoscale dispersion of silicate layers in the polymer matrix. The nanocomposites produced from our laboratory can provide a stable tensile strength at break when the starch content is up to 40 wt %. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 397–404, 2005     

Polypropylene–clay blends compatibilized with MAH‐g‐POE

A series of new Polypropylene (PP)–clay blends, containing 5 wt % clay, were prepared by melt compounding with maleic anhydride grafted poly(ethylene‐co‐octene) (MAH‐g‐POE) as the compatibilizer by varying its content from 0 to 20 wt %. The effect of MAH‐g‐POE on the PP–clay miscibility was examined by X‐ray diffraction (XRD), scanning electronic microscope (SEM) observation, differential scanning calorimeter (DSC) analysis, dynamic mechanical thermal analysis (DMTA), and rheological testing in sequence. The results showed that the addition of MAH‐g‐POE could improve the dispersion of clay layers in PP matrix and promoted the interaction between PP molecules and clay layers. At 10 wt % MAH‐g‐POE, the PP–clay blend exhibited a highest value of Tc,onset and Tg as well as a biggest melt storage modulus (G′), indicating the greatest PP–clay interaction. On the other hand, improved toughness and stiffness coexisted in blends with 5–10 wt % loading of MAH‐g‐POE. In view of SEM and DMTA observations, MAH‐g‐POE was well miscible with the PP matrix, even with the concentration up to 20 wt %. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2558–2564, 2006     

Morphology and thermal and mechanical properties of phosphonium vermiculite filled poly(ethylene terephthalate) composites

A series of poly(ethylene terephthalate) (PET)/phosphonium vermiculite (P‐VMT) composites were prepared by a melt‐blending method, and we investigated the morphology and thermal and mechanical properties of the composites. We prepared P‐VMT with quaternary phosphonium salts using the common method followed by a cation‐exchange reaction. X‐ray diffraction showed that the phosphonium surfactants were partially intercalated into the vermiculite layers, The d‐spacing of the PET–clay sample was somewhat less than that of the P‐VMT because some degradation of the surfactant took place during melt processing. Compared with PET, the PET–clay composites had a lower decomposition temperature and showed a 17.4% increase in the tensile strength with a P‐VMT content of 3 wt %. Scanning electron microscopy and transmission electron microscopy demonstrated that P‐VMT had a homogeneous dispersion and good compatibility in the polymer matrix with a low content of additive and indicated that the P‐VMT content of 3 wt % was optimal. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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     

Study the effects of Cloisite15A nanoclay incorporation on the morphology and gas permeation properties of Pebax2533 polymer

In this study, mixed matrix membranes (MMMs) were prepared using commercially available poly(ether‐b‐amide) (Pebax2533) as polymer matrix and organically modified montmorillonite (OMMt) as filler with the aim of investigating their gas permeation properties. The prepared membranes were characterized by Fourier‐transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), scanning electron microscope (SEM), thermal gravimetric analysis, and tensile strength analyses. Gas permeation properties of all the prepared membranes were evaluated at different pressures and clay loadings. Results of FTIR and SEM confirmed the appropriate adhesion between polymer and nanoclays so that no void formation was observed in the polymer/clay interface. XRD results showed that in low loading, clay dispersion occurred as exfoliated‐intercalated and at high loading as intercalated‐phase separated. Results of gas permeation test showed that by adding layered and impermeable clay particles to the polymer matrix, the permeation of soluble CO₂ gas reduced by 28% for the highest clay loading. By increasing of pressure from 2 to 6 bar, CO₂/CH₄ permselectivity increased at all nanoclay loadings. The highest CO₂/CH₄ selectivity was obtained for 6 wt % clay MMM at all pressures, while the highest CO₂/H₂ selectivity was achieved for neat polymer at 6 bar. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45302.     

New clay‐reinforced nanocomposites based on a polycarbonate/polycaprolactone blend

New clay‐reinforced polymer nanocomposites based on poly(carbonate of bisphenol A) (PC)/poly(caprolactone) (PCL) blends have been obtained by mixing PC with minor amounts of PCL in which a widely dispersed organically modified montmorillonite (OMMT) was present. Upon the addition of PCL/OMMT, the T_g of the matrix and the viscosity of the nanocomposites decreased and therefore processability increased. This was attributed to both the presence of PCL and the migration of some surfactant to the polymeric matrix. The intercalation level observed by X‐Ray diffraction was similar to that obtained in PC nanocomposites, and the dispersion level was at least similar, as observed directly by transmission electron microscopy and indirectly by modulus measurements. However, the benefits of both clay and PCL were present together in the nanocomposites, besides the improved processability and the expected improvement of barrier properties. This led to increases in modulus of elasticity, yield strength, and although slight, mostly in ductility. POLYM. ENG. SCI., 46:864–873, 2006. © 2006 Society of Plastics Engineers     

Nanoclay plating of cellulosic fiber surfaces

A basic problem in making cellulose‐reinforced composites is achieving a dispersion of cellulosic fibers in an often olephinic polymer matrix. Drying cellulosic fibers results in the formation of fiber flocs/nodules because of their strong interfiber bonding, and this makes the hydrophilic cellulosic fibers difficult to disperse in a hydrophobic matrix material. One common approach to alleviate floc formation is to adsorb cationic surfactant onto anionically charged cellulose, which reduces the interfiber bonding, decreases floc formation and gives better compatibility with the matrix. In this report, a different approach is taken, namely to adsorb nanoclays onto the cellulosic fibers, and thereby reduce the natural hydrogen‐bonding affinity between fibers. In a second report, the same technology will be shown to be advantageous to decrease floc formation in oleophinic composites reinforced with cellulosic fibers. This article summarizes experiments aimed at optimizing the chemistry of deposition of montmorillonite clay onto fiber surfaces. The aim was to optimize the chemical conditions for the heterodeposition of the anionic clay onto cationically charged fluff pulp. The experiments were designed to provide a theoretical framework for the deposition of the nanoclay onto the pulp fibers. High M_w p‐DADMAC and an exfoliated clay (achieved by passing the clay through a homogenizer) were used. As expected, a certain degree of charge overcompensation by adding an electrolyte was necessary to bring about deposition. The adsorbed amount of clay could be calculated from the charge balance between the overcompensated charge and the net clay charge, constituting the theoretical framework for nanoclay heterodeposition. As expected, montmorillonite clay greatly destroyed the joint strength between fibers (determined by evaluating the strength of paper made from treated fibers). The surface coverage (determined by ESCA) was shown to be a linear function of the attached amount of clay, and ～3% clay was required to fully cover the fiber surfaces. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(trimethylene terephthalate) nanocomposite fibers comprising different organoclays: Thermomechanical properties and morphology

Poly(trimethylene terephthalate) (PTT) nano composites were synthesized by in situ polymerization at high temperature with two thermally stable organoclays: 1,2‐dimethylhexadecylimidazolium‐montmorillonite (IMD‐MMT) and dodecyltriphenyl phosphonium‐MMT (C₁₂PPh‐MMT). PTT hybrid fibers with various organoclay contents were melt‐spun at various draw ratios (DRs) to produce monofilaments. The thermomechanical properties and morphologies of the PTT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide‐angle X‐ray diffraction, electron microscopy, and mechanical tensile properties analysis. The nanostructure of the hybrid fibers was observed by both scanning and transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. Unlike the hybrids containing IMD‐MMT, the clay layers of the C₁₂PPh‐MMT hybrid fiber were more dispersed into the matrix polymer. The thermal stability and tensile properties of the hybrid fibers increased with increasing clay content for DR = 1. However, as DR increased from 1 to 9 the ultimate strength and initial modulus of the hybrid fibers with IMD‐MMT increased slightly whereas those of C₁₂PPh‐MMT hybrid fibers decreased slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4535–4545, 2006     

Nanoclay Reinforcement of Liquid Silicone Rubber

Siloxane modified montmorillonite clay was prepared from sodium montmorillonite and quaternary ammonium-containing siloxane surfactant. X-ray diffraction and Fourier transform infrared analyses indicated that the polysiloxane oligomer chains were successfully grafted onto the surface of the montmorillonite clay platelets. The siloxane modified montmorillonite clay and commercial organo-modified montmorillonite and bentonite clays were incorporated into a rapid-cure liquid silicone rubber (LSR) matrix. The morphologies of the LSR/nanoclay composites were analyzed by SEM and TEM, and partial exfoliation of the silicate nanolayers of the clay platelets was observed. Up to a 20% reduction in water vapor permeability was achieved as well as a 24% improvement in tear strength and a 40% improvement in the compression set.     

Effect of maleated polypropylene as coupling agent for polypropylene composites reinforced with hemp strands

New composites based on poly(propylene) as polymer matrix and hemp strands as natural reinforcement have been developed by injection‐molding. The materials were previously mixed in a two roll mill to induce the dispersion of the fiber inside the polymer. To improve the adhesion between both components, maleated poly(propylene) was added as coupling agent, at 4% wt/wt with respect to hemp strands. The addition of this amount of this coupling agent to the formulation modified with 40 wt % of hemp strands increases the ultimate tensile strength (σ_t) and flexural strength (σ_f) up to 49 and 38%, respectively, compared with the composite without coupling agent. The interaction between the surface of hemp strands and the coupling agent was determined by FT‐IR spectroscopy assuming that a covalent bond was established, avoiding the adverse effect of the poor compatibility at the interface for this kind of composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 833–840, 2006     

Effect of clay on the properties of poly(styrene‐co‐acrylonitrile)–clay nanocomposites

Clay‐dispersed poly(styrene‐co‐acrylonitrile) nanocomposites (PSAN) were synthesized by a free radical polymerization process. The montmorillonite (MMT) was modified by a cationic surfactant hexadecyltrimethylammonium chloride. The structures of PSAN were determined by wide‐angle X‐ray diffraction and FTIR spectroscopy. The dispersion of silicate layers in the polymer matrix was also revealed by transmission electron microscopy (TEM). It was confirmed that the clay was intercalated and exfoliated in the PSAN matrix. The increased thermal stability of PSAN with the addition of clay was observed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dielectric properties of PSAN were measured in the frequency range 100 Hz to 1 MHz at 35–70°C. It was found that the dielectric constant from the dipole orientation had been suppressed due to the intercalation of clay. The dielectric loss is strongly related to the residual sodium content of clay, which increases as the sodium content increases by the addition of clay. Copyright © 2004 Society of Chemical Industry     

Improved thermostability and interfacial matching of nanoclay filler and ethylene vinyl alcohol matrix by silane‐modification

The interfacial compatibility between polymers and nanoclay fillers as well as the thermostability of both components are important characteristics for processing them into polymer composites. While the polymer component is often grafted using common polymerization reactions, the nanoclay component is usually surface modified by surfactant treatment to improve compatibility. In the present study, the polymer ethylene vinyl alcohol and a nanoclay filler based on natural bentonite are both surface modified by different silanes, 3‐glycidoxypropyltrimethoxysilane and methacryloxymethyltrimethoxysilane and their interfacial properties are investigated by inverse gas chromatography. The silane‐modified samples had improved interfacial properties as reflected by a significant increase in dispersive and specific surface energies. Lewis acidities were determined using chloroform and 1,4‐dioxane as polar probes and showed a good match between polymer and nanofiller interfaces. Lewis acidity was generally lower after silane‐modification. Silanization yielded increased thermal stability of the treated samples. Thus, silanization led to improved compatibility and enhanced thermal stability which facilitates further processing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41227.     

Morphologically dependent alternating‐current and direct‐current breakdown strength in silica–polypropylene nanocomposites

In this article, we report the synthesis of a new bimodal surface ligand morphology on silica nanoparticles. Combining grafting‐to and grafting‐from approaches, in this study, we demonstrated the efficacy of anthracene surface modification for improving the dielectric breakdown strength (DBS) under alternating‐current and direct‐current conditions and that of a matrix‐compatible polymer brush for controlling the nanofiller (NF) dispersion. Ligand‐modified spherical colloidal SiO₂ nanoparticles (～14 nm in diameter) were mixed into polypropylene, and the resulting dispersion was improved over the unmodified particles, as shown with transmission electron microscopy. The results suggest that the electronic structure of the anthracene‐modified particle surface was critical to the improvement in DBS. In addition, the DBS of the composite was shown to depend on the dispersion state of the filler and the mode of stress; this indicated that the individually dispersed nanoparticles were not necessarily the optimal morphology for all stress conditions. Additionally, the precise nature of the matrix‐compatible brush was less important than the NF dispersion it produced. The bimodal grafted architectural design has provided a promising solution for the control of the dispersion and surface properties, especially for high‐molecular‐weight polymer matrices. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44347.     

The effect of swelling agents and characterization of polyurethane/polymer electrolytes/clay composites

This study discusses the interaction model and characterization of a clay organic processed with different swelling agents blended with PU/polymer electrolytes. The change in d‐spacing of the clay and modified clay in the PU/polymer electrolytes blends was analyzed using X‐rays. A rigid‐body pendulum rheometer was used to determine the curing behavior of PU/polymer electrolytes matrix in the clay and modified clay with different proportions. Dynamic mechanical analysis has been applied to discuss the intermolecular interaction between clay and organoclay with different proportions and PU/polymer electrolytes blends. We have also analyzed the mechanical properties, stress, and strain. As a result, the compatibility of polymer electrolytes, clay, and organoclay is better. The swelling agent that intercalated among the layers of clay will be crowded out and adsorbed onto the surface of clay. The curing time, intermolecular interaction, thermal properties, and mechanical properties of composites were clearly influenced by the clay and swelling agent. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1206–1214, 2005     

Preparation and characterization of poly(butylene terephthalate) nanocomposites with various organoclays

Layered‐silicate‐based polymer–clay nanocomposite materials were prepared depending on the surface modification of montmorillonite (MMT). Nanocomposites consisting of poly(butylene terephthalate) (PBT) as a matrix and dispersed inorganic clay modified with cetyl pyridinium chloride (CPC), benzyl dimethyl N‐hexadecyl ammonium chloride, and hexadecyl trimethyl ammonium bromide by direct melt intercalation were studied. The organoclay loading was varied from 1 to 5 wt %. The organoclays were characterized with X‐ray diffraction (XRD) to compute the crystallographic spacing and with thermogravimetric analysis to study the thermal stability. Detailed investigations of the mechanical and thermal properties as well as a dispersion study by XRD of the PBT/clay nanocomposites were conducted. X‐ray scattering showed that the layers of organoclay were intercalated with intercalating agents. According to the results of a differential scanning calorimetry analysis, clay acted as a nucleating agent, affecting the crystallization. The PBT nanocomposites containing clay treated with CPC showed good mechanical properties because of intercalation into the polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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     

Effect of clay exfoliation and organic modification on morphological,dynamic mechanical,and thermal behavior of melt‐compounded polyamide‐6 nanocomposites

Polyamide‐6/clay nanocomposites were prepared employing melt bending or compounding technique followed by injection molding using different organically modified clays. X‐ray diffraction and transmission electron microscopy were used to determine the molecular dispersion of the modified clays within the matrix polymer. Mechanical tests revealed an increase in tensile and flexural properties of the matrix polymer with the increase in clay loading from 0 to 5%. C30B/polyamide‐6 nanocomposites exhibited optimum mechanical performance at 5% clay loading. Storage modulus of polyamide‐6 also increased in the nanocomposites, indicating an increase in the stiffness of the matrix polymer with the addition of nanoclays. Furthermore, water absorption studies confirmed comparatively lesser tendency of water uptake in these nanocomposites. HDT of the virgin matrix increased substantially with the addition of organically modified clays. DSC measurements revealed both γ and α transitions in the matrix polymer as well as in the nanocomposites. The crystallization temperature (T_c) exhibited an increase in case of C30B/polyamide‐6 nanocomposites. Thermal stability of virgin polyamide‐6 and the nanocomposites has been investigated employing thermogravimetric analysis. POLYM. COMPOS., 28:153–162, 2007. © 2007 Society of Plastics Engineers     

Visualisation of Nanoclay Dispersion in Polymer Matrix by High‐Resolution Electron Microscopy Combined with Electron Tomography

In order to establish the structure‐property relationship in the case of clay containing polymer nanocomposites, detailed understanding of silicate layers dispersion into the polymer matrix is necessary. In this study, biodegradable poly[(butylene succinate)‐co‐adipate] (PBSA) was chosen as a model polymer and the nanocomposite of PBSA with organically modified montmorillonite (OMMT) was prepared via the melt‐mixing in a batch mixer. The degree of dispersion of silicate layers in the PBSA matrix was investigated by means of wide angle X‐ray diffraction, small angle X‐ray scattering, high‐annular‐angle‐dark‐field scanning transmission electron microscopy, and high resolution transmission electron microscopy combined with electron tomography. Results demonstrated the homogeneous dispersion of clay platelets in the PBSA matrix. However, the true exfoliation of silicate layers in the polymer matrix is quite difficult to achieve, although there are strong favourable interactions between the polymer matrix and the OMMT surface.

     

Preparation of Polyetheramine‐Grafted Lignin and Its Application in UV‐Resistant Polyurea Coatings

Lignin‐containing polyurea coating with good ultraviolet (UV) resistance is prepared by partially substituting polyetheramine with enzymatic hydrolysis lignin. Lignin is first grafted by polyetheramine chains via Mannich reaction, which improves its interfacial compatibility with polyurea matrix. The influences of the modified lignin on the chemical and corrosion resistance, UV‐aging property, and thermal stability of the polyurea coatings are studied. It is demonstrated that lignin‐containing polyurea coatings exhibit excellent UV‐aging properties. Aminating lignin with polyetheramine improves its dispersion in the polymer matrix. This work offers a novel method for the high‐value utilization of biomass lignin in anti‐UV polyurea coatings.     

Improvement of processability of clay/polylactide nanocomposites by a combinational method: In situ polymerization of L‐lactide and melt compounding of polylactide

A modified clay/polylactide nanocomposite was prepared. The clay was modified by grafting polylactide chains onto the surface of clay. The modified clay was melt‐compounded with a high‐molecular‐weight polylactide matrix. This novel clay/polylactide nanocomposite showed high shear‐thinning behavior when the molecular weight of the grafted poly(L ‐lactide) was rather high. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1664–1669, 2006