Green Route for the Synthesis of Alanine-based Poly(amide-imide) Nanocomposites Reinforced with the Modified ZnO by Poly(vinyl alcohol) as a Biocompatible Coupling Agent

The objective of this article was fabrication and characterization of novel optically active poly(amide-imide)/zinc oxide nanocomposites with different modified ZnO nanoparticle contents under ultrasonic irradiation technique. For better dispersion of ZnO nanoparticles in a polymer matrix, their surface was modified with poly(vinyl alcohol) as a coupling agent. Effects of poly(vinyl alcohol) modifier on dispersity of nanoparticles, morphological structures, and thermal stability of the obtained nanoparticles were studied by several techniques. According to the transmission electron microscopy images of the nanocomposite, the average diameter of particles was around 7–15 nm in the poly(amide-imide).     

Synthesis and characterization of poly(propylene carbonate)/modified sepiolite nanocomposites

A series of poly(propylene carbonate) (PPC)/modified sepiolite (mSp) nanocomposites with different mSp contents were prepared via a solution‐based processing method. The modified sepiolite was obtained by fabricating sepiolite with methyl trimethoxysilanes (MTMS) gel. The effect of mSp amount, in the range 1–10 wt%, on the morphology, mechanical properties, and thermal degradation of PPC was investigated by means of scanning electron microscopy (SEM), X‐ray diffractometry (XRD), static strenching analysis, thermogravimetric analyses (TGA), differential scanning calorimetry (DSC). Morphological studies showed the homogeneous dispersion of mSp in the PPC matrix whose structure remains amorphous. The nanoscale dispersion of mSp significantly enhanced the mechanical properties and thermal stability. The thermal motion and degradation of the polymer occur at higher temperature in the presence of mSp because of the strong interfacial adhesion between the two components. POLYM. COMPOS., 21–27, 2016. © 2014 Society of Plastics Engineers     

Poly(vinyl alcohol) nanocomposites with sepiolite and heat‐treated sepiolites

Poly(vinyl alcohol) (PVA) nanocomposites with pristine sepiolite and heat‐treated (HT) sepiolites were prepared by the method of solution dispersion. The measurements of XRD, FTIR, TEM, and AFM were used for the characterization of the nanocomposites. Furthermore, thermal and optical properties were investigated by TG/DTG/DTA and UV‐visible transmission spectra, respectively. Both the effects of sepiolite/polymer ratio and the structural changes in sepiolite on heating were examined in terms of changes in the properties of the nanocomposites. The addition of sepiolite/HT sepiolites into the PVA matrix resulted in a decrease in the thermal decomposition temperatures of the nanocomposites because of the fact that sepiolite and HT sepiolites facilitated the elimination of the water and acetate groups from the PVA in the second step based on the TG/DTG studies. The HT sepiolites‐PVA nanocomposites had lower thermal stability and more influenced optical clarity than those of the sepiolite PVA, at the same filler levels. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and Characterization of New Poly(ether-amide-imide)/Amino-Functionalized Fe3O4 Nanocomposites

New poly(amide-imide)/amino functionalized Fe₃O₄ nanocomposites were successfully fabricated through solution intercalation technique. A poly(amide-imide) derived from an imide-containing diacid and ether linkage diamine was synthesized and characterized. Aiming to have better compatibility, the hydrophilic nature of Fe₃O₄@SiO₂ was changed into organophilic using N-[3-(trimethoxysilyl)propyl]ethylenediamine. The amino-functionalized Fe₃O₄ showed well dispersion in the poly(amide-imide) matrix. Thermal gravimetric analysis results indicated that char yields of the nanocomposites were improved. Microscale combustion calorimetry results showed that poly(amide-imide) had good flame retardancy and amino-functionalized Fe₃O₄ has further improved this property of poly(amide-imide).     

Preparation of Poly(Vinyl Alcohol) Nanocomposite Films Reinforced with Poly(Amide–Imide)/CuO Having N-trimellitylimido-L-valine Linkages for the Improvement of Mechanical and Thermal Properties

In this investigation, nanocomposite films were fabricated by dispersion of poly(amide–imide)/CuO nanocomposites as nanofiller in the poly(vinyl alcohol) matrix via an ultrasonic process. The nanofiller was prepared and mixed with PVA matrix. After dispersion of nanofiller into the poly(vinyl alcohol), the mechanical properties of the nanocomposites were improved. For example, the addition of 6 wt% nanofiller into the poly(vinyl alcohol) matrix enhanced the tensile modulus by 39%. The residual weight at 800°C was 7% for pure poly(vinyl alcohol) while the nanocomposites illustrated 12–19% residue at this temperature.     

Green Synthesis of Salicylic Acid-Based Poly(amide-imide) in Ionic Liquid and Composite Formation with Multiwalled Carbon Nanotube

A new salicylic acid-containing diacid monomer was synthesized by an established synthetic procedure from readily available reagents. The obtained diacid was used in the preparation of a thermally stable poly(amide-imide) by direct polycondensation with 4,4′-diphenylmethanediamine using 1,3-diisopropylimidazolium bromide ionic liquid as a green medium. The prepared polymer was used as matrix for preparation of multiwalled carbon nanotube/poly(amide-imide) composites in three multiwalled carbon nanotube concentrations (5, 10, and 15?wt%). The products were characterized for assessing the spectroscopic, thermal, and morphological properties by several methods. A homogeneous dispersion of multiwalled carbon nanotubes in the poly(amide-imide) matrix was observed by microscopy techniques.     

Preparation and characterization of sepiolite‐poly(ethyl methacrylate) and poly(2‐hydroxyethyl methacrylate) nanocomposites

Poly(ethyl methacrylate) (PEMA) and poly(2‐hydroxyethyl methacrylate) (PHEMA) nanocomposites with sepiolite in pristine and silylated form were prepared using the solution intercalation method and characterized by the measurements of XRD, TEM, FTIR‐ATR, TG/DTG, and DSC. The TEM analysis indicated that the volume fraction of fibers in sepiolite decreased and the fiber bundles dispersed in PEMA and PHEMA at a nanometer scale. These results regarding TEM micrographs were in agreement with the data obtained by XRD. The increase in thermal stability of nanocomposites of PEMA is higher than that of PHEMA according to the data obtained from TG curves. The DTG analysis revealed that sepiolite/modified sepiolite caused some changes, as confirmed by FTIR in the thermal degradation mechanism of the polymers. T_g temperatures of PEMA and PHEMA usually increased upon the addition of sepiolite/modified sepiolite. In addition, modification of sepiolite with 3‐APTS had a slight influence on thermal properties of the nanocomposites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Influence of sepiolite and electron beam irradiation on the structural and physicochemical properties of polyethylene/starch nanocomposites

This study presents the influence of functionalized sepiolite and electron beam irradiation on the structural and physicochemical properties of high density polyethylene (HDPE)/starch blends. HDPE/Starch blends containing varying amounts of sepiolite [from 2 to 6 parts per hundred (phr) resins] were prepared in an internal mixer and subjected to electron beam irradiation. The structural analysis of nanocomposites revealed an interaction among the incorporated components. The morphological analysis depicted the void‐free dispersion of additives in the nanocomposites as well as an improvement in the compatibility between the matrix and additives. The sepiolite served as a heat barrier and improved the thermal stability of blend upto a maximum of 45°C. The ultimate tensile strength and Young's modulus (E) of blend was slightly improved with the incorporation of sepiolite and radiation. On the contrary, the E of nanocomposites was significantly improved with radiation dose. The sample containing 6 phr sepiolite and irradiated at 100 kGy showed 61% increase in E when compared with its unirradiated counterpart. Likewise, the thermal distortion temperature and Vicat softening temperature of the blend was slightly changed with the incorporation of sepiolite and radiation dose; however, increased with radiation dose in the nanocomposites. The improvements in the properties of nanocomposites with radiation dose were assigned to the formation of radiation‐induced crosslinked network as revealed by gel content analysis. The results presented here revealed substantial improvements in the properties of nanocomposites with irradiation, which pave way for their potential applications in various sectors including packaging materials for radiation sterilizable products. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Characterization,degradation and biocompatibility of PBAT based nanocomposites

The characterization, biocompatibility and hydrolytic degradation of poly(butylene adipate-co-terephthalate) (PBAT) and its nanocomposites based on 10 wt.% of an unmodified sepiolite and unmodified and modified montmorillonites and fluorohectorites were studied. All nanocomposites were prepared by melt blending using an internal mixer at 140 °C, showing a good level of clay distribution and dispersion into the PBAT matrix, especially those systems based on modified clays and sepiolite. The compression tests of all nanocomposites showed significant increases in the mechanical properties of PBAT matrix, associated to a reinforcement effect of nanoclays. An effective hydrolytic degradation of PBAT and nanocomposites in a phosphate buffered solution of pH 7.0 at 37 °C was also obtained. The addition of nanoparticles tended to delay slightly the hydrolysis of the polymer matrix in the early degradation stages; afterwards the presence of nanoparticles did not affect significantly the degradation trend of the polymer. Cytotoxicity tests, protein absorption analyses and complete blood count tests indicated that nanocomposites showed good biological safety: non-cytotoxicity, higher in vitro hemocompatibility than neat PBAT and non-negative hemostatic effects after contacting with blood. In general, these results showed that all the studied PBAT based nanocomposites could be very attractive for various tissue engineering applications, particularly to bone defects.     

Synthesis of New PI/MWCNT Containing Sulfone Groups via In Situ Polymerization: Study on Thermal,Electrical, and Optical Properties

New series of polyimide (PI) nanocomposites reinforced with three different amounts of multiwalled carbon nanotubes (MWCNT; 0.5, 1, and 3 wt%) were prepared by casting, evaporation and thermal imidization. Homogeneous dispersion of MWCNT in PI matrix was investigated by transmission electron microscopy. The effects of MWCNT on the thermal properties of the PI were investigated by thermogravimetric analysis. The results showed that the thermal stability of the nanocomposites enhanced with the increasing MWCNTs content. The resultant PI/MWCNT nanocomposites were electrically conductive with significant conductivity enhancement at 3 wt% MWCNT, which is favorable for many practical uses.     

Sepiolite‐reinforced epoxy nanocomposites: Thermal,mechanical, and morphological behavior

A bisphenol A‐based epoxy resin was modified with pristine sepiolite and an organically surface‐modified sepiolite and thermally cured using two different curing agents: an aliphatic and a cycloaromatic diamine. The nanocomposites were characterized by dynamic mechanical analysis (DMA), rheology, thermogravimetric analysis (TGA), and electron microscopy. The initial sepiolite–epoxy mixtures show a better dispersion for the sepiolite‐modified system that forms a percolation network structure. Mechanical properties have also been determined. The flexural modulus of the epoxy matrix slightly increases by the incorporation of the organophilic sepiolite. The flexural strength of the sepiolite‐modified resin cured with the aliphatic diamine increased by 10%, while the sepiolite‐modified resin cured with the cycloaromatic diamine resulted in a lower flexural strength, as compared with the unmodified resin. Electron micrographs revealed a better nanodispersion of the sepiolite in the epoxy matrix for the organophilic modified sepiolite nanocomposite. The initial thermal decomposition temperature did not change significantly with the addition of sepiolite, whereas mechanical properties were affected. The reduced flexural strength was attributed to the stress concentrations caused by the sepiolite modifier. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characterization and Properties of Poly(methyl methacrylate)/Graphene,Poly(methyl methacrylate)/Graphene Oxide and Poly(methyl methacrylate)/p-Phenylenediamine-Graphene Oxide Nanocomposites

In this study, poly(methyl methacrylate)/p-phenylenediamine-graphene oxide, poly(methyl methacrylate)/graphene, and poly(methyl methacrylate)/graphene oxide nanocomposite series were prepared using simple solution blending technique. In poly(methyl methacrylate)/p-phenylenediamine-graphene oxide series, graphene oxide modified with p-phenylenediamine was used to improve its dispersion and interfacial strength with matrix. Morphology study of poly(methyl methacrylate)/p-phenylenediamine-graphene oxide nanocomposite revealed better dispersion of p-phenylenediamine-graphene oxide flakes and gyroid patterning of poly(methyl methacrylate) over the filler surface. Due to nonconducting nature of graphene oxide, there was no significant variation in the thermal or electrical conductivity of these nanocomposites. Thermal conductivity of poly(methyl methacrylate)/p-phenylenediamine-graphene oxide 1.5 was 1.16 W/mK, while the electrical conductivity was found to be 2.3 × 10^?3 S/cm.     

Organo-Modification of Mesoporous SBA-15 with Chiral Diacid and its Utilization for the Preparation of L-Phenylalanine-Based Poly(amide-imide) Nanocomposites

In this study ultrasonic irradiation has been proposed for organo-modification of SBA-15 with N,N′-(pyromellitoyl)-bis-L-phenylalanine. Chiral poly(amide-imide) (PAI) was synthesized by the direct polymerization of L-chiral diacid and 4,4-diaminodiphenyle sulfone in molten tetrabutylammonium bromide. Different nanocomposites (NCs) of modified SBA-15 and chiral PAI were synthesized by solution intercalation method under ultrasonic irradiation. The structures and morphology of the hybrids were investigated by different techniques. The NCs showed an improvement in the thermal properties in comparison with the neat PAI. Transmission electron microscopy images show well-ordered hexagonal arrays of mesopores SBA and the average distances between neighboring pores is around 3–5 nm.     

Preparation of a long-alkyl-chain silane grafted organic montmorillonite and its nanocomposite with SEBS

In this study, a modified montmorillonite (W-H-OMMT) was prepared by intercalating pristine montmorillonite using a phosphorus salt and a subsequent grafting using a long-alkyl-chain silane, and the nanocomposites with poly[styrene–(ethylene-co-butylene)–styrene] (SEBS) were prepared by melt blending. The pristine and the modified MMT were characterized by XRD, FT-IR, XPS and SEM. The morphology of the SEBS nanocomposites was studied using XRD, SEM and TEM, and the results can be correlated well with transparency, color, surface contact angle, rheological behavior, thermal and mechanical properties of the nanocomposites. As compared with pristine and the modified clay, more uniform dispersion and improved compatibility are observed for the W-H-OMMT in the SEBS matrix, resulting in better transparency and more hydrophobic surface for the SEBS/W-H-OMMT nanocomposite. Better thermal stability, a synergetic effect in tensile strength and elongation at break were observed, which can be attributed to well dispersion of the W-H-OMMT, as well as perfect adhesion between the W-H-OMMT and the SEBS matrix from the enhanced molecular interaction between the long-alkyl chain and the SEBS molecules. Compared to pure SEBS, the strength and elongation of SEBS/W-H-OMMT nanocomposite increased by 8.5 and 7.6 %; meanwhile, the water contact angel and the 50 % weight loss temperature increased by 5.3 and 13.1 %, respectively. Appropriate silane grafted organic montmorillonite provided an efficient way for the overall performance improvement of SEBS.     

Synthesis and characterization of linear low‐density polyethylene/sepiolite nanocomposites

Linear low‐density polyethylene (LLDPE)/sepiolite nanocomposites were prepared by melt blending using unmodified and silane‐modified sepiolite. Two methods were used to modify sepiolite: modification before heat mixing (ex situ) and modification during heat mixing (in situ). The X‐ray diffraction results showed that the position of the main peak of sepiolite remained unchanged during modification step. Infrared spectra showed new peaks confirming the development of new bonds in modified sepiolite and nanocomposites. SEM micrographs revealed the presence of sepiolite fibers embedded in polymer matrix. Thermogravimetric analysis showed that nanocomposites exhibited higher onset degradation temperature than LLDPE. In addition, in situ modified sepiolite nanocomposites exhibited higher thermal stability than ex situ modified sepiolite nanocomposites. The ultimate tensile strength and modulus of the nanocomposites were improved; whereas elongation at break was reduced. The higher crystallization temperature of some nanocomposite formulations revealed a heterogeneous nucleation effect of sepiolite. This can be exploited for the shortening of cycle time during processing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis,Characterization and Conducting Properties of Nanocomposites of Intercalated 2-Aminophenol with Aniline in Sodium-Montmorillonite

A simple method was used to synthesize poly(2-aminophenol), poly(2-aminophenol-co-Aniline) and polyaniline nanocomposites with sodium-montmorillonite (Na-M) using in situ intercalative oxidative polymerization. Morphology and thermal properties of the synthesized nanocomposites were examined by transmission electron microscopy (TEM) and thermogravimetric analysis. The thermal analysis shows an improved thermal stability of the nanocomposites in comparison with the pure poly(2-aminophenol). The intercalation of polymers into the clay layers was confirmed by X-ray diffraction studies, TEM images and FTIR spectroscopy. In addition, the room temperature conductivity values of these nanocomposites varied between 8.21 × 10^?5 and 6.76 × 10^?4 S cm^?1. The electrochemical behavior of the polymers extracted from the nanocomposites, has been analyzed by cyclic voltammetry. Good electrochemical response has been observed for polymer films; the observed redox processes indicate that the polymerization into Na-M produces electroactive polymers.     

Epoxy-Modified Mesua ferrea L. Seed-Oil-Based Polyester/Clay Nanocomposites

The nanocomposites of epoxy-modified Mesua ferrea L. seed-oil-based polyester resin were designed with 0-5 wt% loadings of organophillic montmorrilonite (OMMT). X-ray diffraction, transmission electron microscopy, and scanning electron microscopy studies revealed very good dispersion of OMMT with exfoliated structure in the matrix. The effects of OMMT on the curing, thermal, mechanical, and rheological behaviors of the nanocomposites were also investigated. Two times’ improvement in tensile strength, 2 kg increment in scratch hardness, and 68°C enhancement in thermal degradation temperature were obtained for the nanocomposites with 5 wt% OMMT loading compared to pristine polyester.     

Synthesis and characterization of biodegradable poly(l-lactide)/layered double hydroxide nanocomposites

The effects of layered double hydroxide (LDH) composed by calcium/aluminum and magnesium/iron as divalent/trivalent cations and intercalated with dodecyl sulfate anion in the properties of poly(l-lactide) (PLLA) were analyzed. Two PLLA nanocomposites were produced by in situ intercalative bulk polymerization using 1 and 2 wt% of LDH. The PLLA nanocomposites were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and ultraviolet–visible spectroscopy (UV–VIS). XRD results demonstrated that PLLA nanocomposites showed a good dispersion of LDH in the polymeric matrix, which may have caused an increase in thermal stability indicated by thermogravimetric analysis. UV–VIS analyses showed that PLLA nanocomposites presented lower transmittance values when compared to the neat PLLA, which is an interesting characteristic for plastics used in food packaging. This enhancement in the properties of PLLA nanocomposites can enlarge the range of applications of this material in several areas.     

Laser transmission welding of poly(lactic acid) and polyamide66/sepiolite nanocomposites

Influence of sepiolite nanoclay on the properties of the resulting join between poly(lactic acid) (PLA) and different Polyamide66 (PA66)/nanoclay nanocomposites was studied in this work. Six different polymer nanocomposites based on PA66 were manufactured through a melt compounding process by adding a fixed 1.64 wt % of a commercial IR absorber additive and the respective weight percentages of sepiolite to the polymer matrix. Several nanocomposite/PLA joints were finally performed by means of the transmission laser welding technology and the resulting weldings were characterized in terms of mechanical properties by performing peeling and shearing tests. Furthermore, both welded and mechanically tested samples were also analyzed by scanning electron microscopy in order to study the morphology of the weld seam. The results of the performed tests show that the addition of sepiolite to the PA66 improves the welding performance only in those cases in which the percentage of sepiolite of the nanocomposites is higher than 5 wt %. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46638.     

Grafting of Citric Acid as a Green Coupling Agent on the Surface of CuO Nanoparticle and its Application for Synthesis and Characterization of Novel Nanocomposites Based on Poly(amide-imide) Containing N-trimellitylimido-L-valine Linkage

In this article, at first, citric acid (CA) was used as a capping agent to control the size, dispersion and morphology of copper oxide (CuO) NPs (CuO-CA). The presence of CA on the surface of CuO NPs was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analyses. Then biodegradable poly(amide-imide) (PAI) was synthesized through a polycondensation reaction of N-trimellitylimido-L-valine and 4,4′-methylenebis(3-chloro-2,6-diethylaniline) in green media. PAI/CuO-CA nanocomposites (PAI/CuO-CA NCs) containing different amounts of CuO-CA NPs in the PAI matrix were prepared using an ultrasonic-assisted technique. The PAI/CuO-CA NCs obtained were characterized using different methods.