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This study explores the impact of different levels of halloysite nanotubes (HNT) and d-isomer on the non-isothermal crystallization behavior of the polylactic acid (PLA). The processing conditions, thermal flow, molecular orientation and the presence of nanofillers can affect the crystallinity and properties of PLA. In this work, PLA-based nanocomposite filaments were produced and their crystallization kinetics was studied. The data obtained through experiments, using differential scanning calorimetry at various cooling rates, were analyzed employing the Jeziorny and Mo models. And the activation energy of crystallization was determined by the Friedman method. The results showed that the growth of PLA crystals is three-dimensional, the HNT can accelerate the crystallization process, and crystallization occurs at higher temperatures in the presence of flow. The activation energy increased with addiction of more HNT in the nanocomposite. The study also found that the d-isomer has a more significant influence on the crystallization of PLA than HNT, which can inhibit crystal formation in some cases. These findings provide insights into the factors that can influence the properties of PLA nanocomposites and how they can be optimized. [ABSTRACT FROM AUTHOR]

The manufacture of flexible devices is of immense interest due to their eco-friendliness, economic prospects and wide range of applications in biocompatible devices. Therefore, this paper reports the characterization and properties of chlorinated natural rubber (Cl-NR)/polyindole (PIN) blend with different contents of nickel oxide (NiO) nanoparticles. The formation of blend nanocomposites was analysed by FT-IR, UV spectroscopy, XRD, FE-SEM, DSC and TGA. The FT-IR and UV spectra proved the effective interfacial interaction between nanoparticles and the blend matrix, with a shift in UV peak intensity with the attachment of NiO at 433 cm−1. The XRD pattern revealed the regular arrangement of the blend matrix due to the presence of nanofiller, resulting in the semicrystalline structure of the composite system. The SEM micrographs revealed a homogeneous distribution of NiO in the blend matrix. The increased degradation temperature in the TGA demonstrated the enhanced thermal stability of the NiO-filled Cl-NR/PIN blend. DSC results showed that the glass transition temperature of the composite increased with NiO content in the blend matrix. The dielectric properties and AC electrical conductivity increased significantly with increasing temperatures, as well as with the addition of nanoparticles up to 5 mass % loading. The inclusion of NiO improved the tensile strength and hardness while reducing the elongation-at-break of nanocomposites. The blend nanocomposite with enhanced thermal stability, glass transition temperature, tensile strength, AC conductivity and dielectric properties enables them to be used in highly flexible electronic applications where traditional elastomeric materials fall short. [ABSTRACT FROM AUTHOR]

Uses of aluminium (Al)-based metal matrix composites (MMCs) have been emerging in variety of applications since several decades. Hence, in the present study, hybrid Al-MMCs were developed using rice husk-extracted highly pure silica (SiO2) and commercial graphite (Grt) as reinforcing materials by powder metallurgical route followed by unique re-sintering. Effect of reinforcements on mechanical as well as thermal properties of Al-MMCs has been determined in this study by various tests. The microscopy, spectroscopy, and X-ray diffraction studies were conducted to characterize the purity and homogeneity of the composites. The hybrid MMCs had shown excellent physical and mechanical properties in terms of surface strength along with being light mass. The Vickers hardness (up to 250 MPa) and compressive strength (up to 341 MPa) of the hybrid nanocomposites has increased significantly on the addition of reinforcements. Thermal properties, including conductivity and linear expansion, were found to be lower for the composites compared to pure Al. Hence, the newly developed rice husk-extracted pure silica and graphite-reinforced hybrid Al-MMCs, particularly the samples of 5SiO2/5Grt/90Al (mass%), can be used as reliable potential materials for several advanced applications including, engine piston, automobile, aviation, and spacecraft components where both mechanical and thermal properties play vital role. [ABSTRACT FROM AUTHOR]

The thin film of nanocomposites was prepared by solution casting methods and characterized by UV–Vis spectra, Raman spectra and scanning electron microscopy (SEM). The optical band gap was determined by Tau plots. The band gap of PVDF was determined with and without BaZrO3 nanoparticles. It could be seen that the band gap decreases from 4.98 to 3.32 eV in the presence of BaZrO3 nanoparticles in PVDF matrix. The Raman study identifies the interacting species with PVDF due to structural change by the addition of BaZrO3 nanoparticles. This helps to understand the potential of new nanocomposites. The structural changes were analyzed by crystallinity, nature of bonds, phase transition from G to B-phase, etc. SEM images represent the change in spherulitic morphology of PVDF by incorporation of BaZrO3 nanoparticles. SEM images are presented the aggregation of BaZrO3 nanoparticles in PVDF matrix causes the generation of larger particles in PVDF chain. DSC supports the crystallization of PVDF nanocomposites upon heating due to the rearrangement of PVDF structure in the presence of BaZrO3 nanoparticles. It is observed that BaZrO3 nanoparticles enrich the structural, thermal and piezoelectric properties due to the change in spherulitic morphology, which creates a large number of micro- to nano-sized pores, increases the β-phase content of the PVDF. [ABSTRACT FROM AUTHOR]

One of the dubious aspects of polymer/clay nanocomposites is its thermal stability compared to the pristine matrix since we can find works indicating different directions with relatively similar materials. This work aims to evaluate the influence of the sepiolite content and the PP-g-MA compatibilizer presence in the polypropylene/sepiolite nanocomposites degradation. PP/Sep nanocomposites were prepared in a twin-screw extruder with 0.75–5 mass% of Sep and with or without 2.5 mass% of PP-g-Ma as a compatibilizer. Material characterizations were performed by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis (TGA). Morphology showed that the nanocomposites presented some needles agglomeration inside the polymer matrix, indicating the use of compatibilizer PP-g-MA was not enough for dispersion in the nanocomposites produced in this work. TGA results showed different results according to the nature of the atmosphere. In the oxidative atmosphere, the stability of nanocomposites was not significantly influenced by the sepiolite concentration, for concentrations lower than 1 mass%, and slightly influenced by the presence of PP-g-MA as a compatibilizer, while concentrations as large as 5 mass% of sepiolite showed a strong influence on the clay concentration. In the inert atmosphere, we observed the influence of the sepiolite concentration, decreasing the stability of the nanocomposite in the whole range of studied concentration. Regarding the presence of 2.5 mass% of PP-g-MA, all the formulations exhibit almost the same profile of mass loss, evidencing that the compatibilizer prevented the catalytic effect of the sepiolite in the thermal degradation of the nanocomposite. [ABSTRACT FROM AUTHOR]

A series of quaternary hybrid kenaf (K) flour-PP nanocomposites, such as PP/KF/MAPP/GNP/MgOH (K-GNP-MgOH), PP/KF/MAPP/GNP/APP (K-GNP-APP) and PP/KF/MAPP/GNP/MgO (K-GNP-MgO) filled with exfoliated graphene nanoplatelets (GNP)-3 phr acting as adjuvant in combination with mineral flame retardants, 20 mass/% magnesium hydroxide (Mg (OH)2) and 20 mass/% magnesium oxide (MgO), and 20 mass/% intumescent ammonium polyphosphate (APP), respectively, were prepared through melt extrusion using co-rotating twin screw extruder. The resulting quaternary nanocomposites were characterized in terms of flame retardancy, thermomechanical, thermal conductivity, thermal behavior, heat deflection temperature (HDT), and mechanical, morphological and structural properties. Mass loss calorimeter data revealed a significant reduction of peak heat release rate, total heat release, effective heat of combustion, mass loss rate and delayed time to ignition due to GNP-MgOH, GNP-MgO and GNP-APP synergistic mechanism in hybrid nanocomposites, respectively. The effective thermal conductivities and HDT of quaternary nanocomposites were found to significantly increase. DSC results revealed enhanced crystallization temperatures with reduced degree of crystallinity, while melting points remained stable. [ABSTRACT FROM AUTHOR]

In this work, polyethylene glycol nanocomposites containing different nanofillers (namely hydrotalcites or boehmites, at 5 mass% loading) were prepared by melt compounding. Their morphology and microstructure were assessed by means of SEM and XRD analyses. The interactions between the different nanofillers and the polymer matrix were evaluated by performing rheological, differential scanning calorimetry and thermogravimetric analyses. The two types of nanofillers were found to differently interact with the polymer matrix. In particular, the rheological tests performed on the systems containing hydrotalcites revealed that the presence of nanofillers affects the relaxation dynamics of the macromolecular chains, in a remarkable way. Conversely, the crystallinity degree of the polymer was influenced by the presence of boehmites only, whose nucleating capability was found to depend on their average size. Finally, the thermo-oxidative stability of the polymer matrix was generally improved by the selected nanofillers, with the only exception of the organo-modified hydrotalcite that significantly anticipated the polymer degradation. [ABSTRACT FROM AUTHOR]

A polyethylene vinyl acetic acid (EVA) nanocomposite comprising of an intumescent agent that incorporates ammonium phosphate monobasic, mono-pentaerythritol, and melamine with a cationic nanoclay was set up through solution blending and melt blending to assess the fire retardancy utilizing a cone calorimeter. The results demonstrated that there was a significant reduction in the peak heat release rate of 70% contrasted with pure EVA. The fire retardancy of the clay-organic intumescent mixture framework composite was more successful than a same amount of additional nanoclay and intumescent agent. To check these outcomes, the residues of cone calorimeter samples were assessed alongside clay d-spacing changes amid utilization. [ABSTRACT FROM AUTHOR]

Industrially relevant nanopowder was synthesised by microwave hydrothermal synthesis to obtain well-controlled composition (ZrO2–AlO(OH) system) which was found to determine a number of physical and thermal characteristics. This study reports variation of particle size, density, specific surface area (SSABET), as well as thermal behaviour of nanopowder mixtures of ZrO2–AlO(OH) in the whole range of compositions. It was found that the onset temperature (Ton) of physically and chemically bounded water desorption depends on the Al3+/or AlO(OH) content. The lower content of Al3+ in the ZrO2–AlO(OH) system, the higher Ton of physically bound water desorption. There are three distinct temperature regions for water decomposition for nanomaterials investigated in air (at approximately 50, 250 and 450 °C). These temperature ranges depend on particle size and chemical composition of ZrO2–AlO(OH) nanopowders. Materials were divided into three groups characterised by different properties: (1) ZrO2 with 2–12% of Al3+, where particle sizes are from 4 to 8 nm, (2) ZrO2 with 30–67% of AlO(OH), where particle sizes are from 10 to 13 nm, and (3) ZrO2 with 80–99% of AlO(OH), where particle sizes are from 13 to 23 nm. AlO(OH) content determines thermal and physico-chemical properties of synthesised ZrO2–AlO(OH) nanopowders. [ABSTRACT FROM AUTHOR]

Novel nanocomposites based on poly(vinyl cinnamate) (PVCin)/zinc oxide (ZnO) were prepared by in situ polymerization method using different mass percentages of ZnO nanoparticles. The formation of nanoparticles in the composites was analysed by TEM, FESEM, XRD, DSC and TG measurements. The TEM and SEM images showed the uniform dispersion of nanoparticles within PVCin matrix. The results of XRD indicated that the metal oxide particles had entered into macromolecular chain of PVCin. The glass transition temperature of the composites was shifted towards higher temperature with the increase in concentration of ZnO nanoparticles. Thermal stability studies showed a remarkable increase in thermal resistance of composites, and the thermal stability increases with an increase in concentration of metal oxide particles. The alternate current (AC) electrical conductivity of prepared composite has been investigated at different temperature at various frequencies. The electrical conductivity was found to be increased with increasing temperature, and it obeys power law. The activation energy was determined from the AC conductivity. DC conductivity of all the composites was much higher than pure PVCin, and the conductivity increases with increase in the concentration of nanoparticles up to 7 mass% and thereafter the conductivity decreases with further addition particles. The experimental conductivity of nanocomposite was compared with different theoretical conductivity using Scarbrick, Bueche and McCullough equation. The conductivity values obtained from McCullough model showed the same trend as experimentally determined conductivity values. [ABSTRACT FROM AUTHOR]

Several composites and nanocomposites based on a polymeric matrix and ceramic fillers are being pursued for use as multifunctional and innovative materials. Nevertheless, there is a series of challenges to be solved in this area such as the understanding of the role of interfaces and the synergy between matrix and fillers. In this work, vulcanized natural rubber nanocomposites were prepared with different concentrations of two kinds of ceramic nanoparticles, potassium strontium niobate (KSrNbO or KSN) and nickel-zinc ferrite (NiZnFeO or NZF), synthesized by a chemical method known as the modified polyol method. Morphological and thermal characterizations were carried out by AFM, TG/DTG, TG/FTIR and DSC. The thermal properties of nanocomposites were compared and discussed as functions of concentration, type and surface of nanoparticles. The results obtained suggest that the base concentration for both types of nanoparticles inside the polymer matrix volume greatly adds to the increase in thermal stability up to 11 % and the glass transition temperature up to 10 °C. A similar evolution for the glass transition temperature ( T ), thermal stability temperature ( T ) and dielectric permittivity ( ε′) was identified, suggesting that these phenomena are mainly dominated by the same mechanisms. These results point to the possibility for the thermal parameter modulation in magnetic and ferroelectric nanocomposites by means of a suitable control of concentration and properties of the KSN and NZF nanoparticles. [ABSTRACT FROM AUTHOR]

The thermal reaction properties of the aluminum nanoparticles/copper (II) oxide nanoparticles/poly(vinylidene fluoride) (Al-NPs/CuO-NPs/PVDF) nanocomposite (mass ratio of Al-NPs/CuO-NPs/PVDF = 20/60/20) were investigated by means of thermogravimetry-differential scanning calorimetry-mass spectrometry (TG/DSC-MS) and X-ray diffraction (XRD) analysis. Al-NPs/PVDF (mass ratio of Al-NPs/PVDF = 50/50) and CuO-NPs/PVDF (mass ratio of CuO-NPs/PVDF = 75/25) nanocomposites were also prepared as a comparison. It is observed that PVDF in the Al-NPs/PVDF nanocomposite acts as an oxidizer. The fluorine ions/fluorinated gases formed at elevated temperatures react with the AlO shell leading to the formation of aluminum fluoride (AlF). The oxide shell is degraded from the reaction between fluoride ions and AlO, leaving the core Al available for reaction with fluorine ions/fluorinated gases. H ( m/z = 2), OH ( m/z = 17), HO ( m/z = 18), HF ( m/z = 20), CF ( m/z = 31) and CHF ( m/z = 33) fragments were detected in the gaseous products. For CuO-NPs/PVDF nanocomposite, oxygen was released due to the decomposition of CuO to CuO and then Cu metal, oxidizing hydrocarbon groups in PVDF. Species of OH ( m/z = 17), HO ( m/z = 18), CO ( m/z = 44), CHF ( m/z = 45) and HF ( m/z = 20) were detected in the gaseous products. The final reduction product of CuO is Cu metal. It is observed that PVDF in the Al-NPs/CuO-NPs/PVDF nanocomposite acts as both oxidizer and reducer in the thermal decomposition. Below 550 °C, PVDF is oxidized by CuO-NPs and oxidizing Al-NPs at the same time, resulting mass reduction. After 550 °C, the remaining Al-NPs and copper (I)/copper (II) oxide will proceed the exothermic solid-state thermite reaction. OH ( m/z = 17), HO ( m/z = 18), CO ( m/z = 44), CHF ( m/z = 45) and HF ( m/z = 20) were the main products of the decomposition of Al-NPs/CuO-NPs/PVDF nanocomposite. [ABSTRACT FROM AUTHOR]

Vapor-grown carbon nanofiber (CNF)-modified soy polyol-based polyurethane (PU) nanocomposites with different hydroxyl value of polyols (OH) were synthesized. The glass transition, thermal stability, mechanical properties, and morphology of the PU nanocomposites were characterized through differential scanning calorimetry, thermogravimetry, universal test machine, and scanning electron microscopy. The addition of CNFs increased the glass transition temperature as well as significantly improved tensile strength and Young's modulus of PU nanocomposites. Meanwhile, thermal and mechanical properties of PU composites were influenced by the different hydroxyl value of polyols due to those different structures. In particular, in the case of 2 mass% CNF addition in PU derived from soy polyol with the OH number of 164 mg KOH g, 20.8 °C improvement in the glass transition temperature, 115 % increment in tensile strength, and nearly eightfold increase in Young's modulus were obtained. [ABSTRACT FROM AUTHOR]

Various compositions of polypropylene (PP) and poly(lactic acid) (PLA) blends were prepared by one-step melt compounding in a twin-screw extruder. Two compositions were selected for investigation of effect of clay and n-butyl acrylate glycidyl methacrylate ethylene terpolymer (PTW) as compatibilizer on thermal properties and non-isothermal crystallization behavior of PP/PLA/clay nanocomposite systems, i.e., PP-rich one (75/25 composition) containing Cloisite 15A and PLA-rich one (25/75 composition) containing Cloisite 30B. The thermal behavior of the systems was investigated by means of differential scanning calorimetry (DSC) and correlated with their microstructures. The narrowing down of the peaks in the wide-angle X-ray scattering pattern of PP-rich blend was associated with an increase in size and/or perfection of the crystals. On the other hand, the broadening of the peaks in PLA-rich blend implied a decrease in the size of the crystals. The calculated interlayer distance, using Scherrer equation, in Cloisite 15A was slightly greater than that of Cloisite 30B. Moreover, an increase of 100 % in interlayer distance showed a greater level of intercalation in PP-rich system as compared to the PLA-rich system. Blending of PP and PLA led to significant changes in the crystallinity behavior of the blends compared to the neat components. Moreover, the incorporation of the both clays into the two systems led to a greater change in the crystallinity degree, comparing to that of unfilled blends. [ABSTRACT FROM AUTHOR]

The novel graphene non-covalently functionalized with amino-terminated dendronized polyamide (DPA) was prepared, then reduced and filled into the PA6 to prepare a series of nanocomposites. The structures and thermal properties of products were investigated by FTIR, XPS, XRD, TEM, SEM, TG, thermal conductivity measurements. The results revealed that mediated by the DPA, the amino-terminated dendronized polyamide functionalized graphene nanosheets (DPA-GNs) show good solubility in the organic solvents and more compatible with organic polymer matrix, which results in a certain promotion in thermal stability and thermal conductivity of nanocomposites. [ABSTRACT FROM AUTHOR]

Polycarbonate (PC)/Zinc oxide (ZnO) nanocomposite films were prepared by a solution mixing method and irradiated by Swift heavy ion at various ions fluences ranging from 1 × 10 to 3 × 10. The surface morphological, structural, and thermal properties of untreated and irradiated PC/ZnO nanocomposite films were investigated by various characterizations techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry, Thermogravimetric (TG) and Thermally stimulated discharge current (TSDC). The XRD pattern reveals that the average crystallite size and percentage of crystallinity decreases with increase of ion fluences. TSDC measurement is an evidence of different type of relaxation process. The activation energy released charge and charge carrier mobility for α-relaxation peak decreases, while relaxation time and peak current increase. TG measurement shows thermal stability and mass loss decreases with ions fluences. FTIR spectra reveal the position of different bonds in PC and nanocomposite films. The glass transition temperature of nanocomposites is observed to be decreases with ion fluences. [ABSTRACT FROM AUTHOR]

Nanocomposites based on Poly (ethyl methacrylate-co-acrylonitrile) containing 20 mol% of acrylonitrile (PEMAN20) and a bentonite from Algeria, modified by Hexadecyltrimethylammonium chloride (HDTMA), were successfully prepared via solution method and in situ polymerization using tetrahydrofuran (THF) as a solvent. Interactions between the clay and polymer matrix occurred and were evidenced by Fourier transform infrared spectroscopy (FTIR). Depending on the clay loading, intercalated or mixed partially exfoliated nanocomposites, investigated by X-ray diffraction (XRD) and transmission electronic microscopy (TEM), were obtained. All elaborated hybrids exhibited an overall improved thermal stability and a moderate increase in their glass transition temperatures compared to virgin (PEMAN20) as evidenced by thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses. Apparent activation energies E of thermal decomposition of these materials were estimated using Tang's method and showed that higher E values were obtained with virgin PEMAN20 compared to its sPEMAN20/OMMT (2 or 4 mass%) nanocomposites. Different thermal decomposition behaviors were, however, observed with hybrids prepared via in situ polymerization. Nanocomposites prepared in the presence of low clay loading (1 % by mass) via both methods were of partially exfoliated structures. The increase of their apparent activation energies, compared to virgin PEMAN20 or PEMAN20/OMMT (2 or 4 mass%) nanocomposites, confirmed the change in the degradation mechanism with the clay loading and the intercalated/exfoliated structures. [ABSTRACT FROM AUTHOR]

The aim of the work was to determine the impact of ultraviolet (UV) irradiation on thermal properties of polylactide-based nanocomposites in the form of a film. Polylactide nanocomposites composed of an organoclay (Nanofil2) and with or without a poly(ε-caprolactone) were exposed to UV radiation in air at a wavelength of maximum 254 nm. Thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) were used in order to investigate the thermal properties of samples during the process of photodegradation. Influence of Nanofil2 quantity and the presence of poly(ε-caprolactone) on thermal properties of polylactide-based nanocomposites during UV exposure has been discussed. It has been established that introduction of Nanofil2 as a nanofiller and a compatibilizing agent into polylactide matrix can affect photodegradation of studied materials. The results of DSC analysis indicate that the rate of degradation process was decreased in the presence of modified montmorillonite. [ABSTRACT FROM AUTHOR]

Poly(lactic acid)/halloysite nanotubes (PLA/HNTs) nanocomposites were prepared using melt compounding followed by compression molding. N, N′-ethylenebis(stearamide) (EBS) was used to improve the dispersion of HNTs and toughen the PLA nanocomposites. The thermal properties of PLA/HNTs nanocomposites were assessed by using differential scanning calorimeter and thermogravimetric analyzer (TG). The TG measurements were performed at both nitrogen and oxygen atmosphere. The mechanical properties of PLA/HNTs were characterized through tensile and impact tests. The morphological properties of the PLA/HNTs nanocomposites were investigated by using transmission electron microscopy and field emission scanning electron microscopy. The degree of crystallinity of PLA nanocomposites was increased slightly by the addition of EBS. The decomposition process of PLA/HNTs depends on the atmosphere reaction during TG test as well as the amount of EBS. The best mechanical properties of PLA/HNTs nanocomposites expressed by the impact strength and elongation at break were achieved by the addition of 5 mass% of EBS. [ABSTRACT FROM AUTHOR]

A new series of four different linear aliphatic ether linked aromatic bismaleimides (AEBMIs) were synthesized from the respective linear aliphatic ether-linked aromatic diamines and maleic anhydride. Further, the POSS-AEBMI nanocomposites were developed by Michael addition reaction of bismaleimide with varying mass percentages of octa(aminophenyl)silsesquioxane and were characterized by the fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Data from thermal studies revealed that the POSS-reinforced AEBMI nanocomposites possesses higher glass transition temperature ( Tg), thermal stability, limiting oxygen index, and lower dielectric constant when compare to that of neat AEBMI. X-ray diffraction and transmission electron microscopy analysis confirmed the molecular level dispersion of POSS in the AEBMI matrix. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is used as a stabilizer in the Pickering emulsion polymerization of methyl methacrylate (MMA) to prepare PMMA/GO nanocomposites. Transmission electron microscope studies of the emulsion polymerization products showed that the average diameter of nanocomposite particles was about 150 nm, the transparent GO flakes covered the surface of the particles, and were well dispersed in polymer matrix. The influence of GO on the thermal stability of PMMA was investigated by thermogravimetry analysis and differential scanning calorimetry. The results showed that the thermal stability and the glass transition temperature ( T) of PMMA/GO nanocomposites were improved obviously compared with PMMA. The apparent activation energy ( E) for the degradation process of PMMA/GO nanocomposites was evaluated by Kissinger method, which indicated that their E s were much higher than those of PMMA both in nitrogen and air atmosphere. [ABSTRACT FROM AUTHOR]

In this study, the influences of expanded graphite oxide (EG) nanosheets presence with and without surfactant on structural and thermal performance of poly(ethylene disulfide) (PEDS)-based nanocomposites are investigated. Sodium dodecylbenzenesulfonate (SDBS) is used as a surfactant for the preparation of modified-EG nanosheets. The structural, morphological, and thermal properties of prepared nanocomposites are studied using X-ray diffraction (XRD), scanning electron microscopy, and differential scanning calorimetry techniques, respectively. XRD patterns of nanocomposites reveal that a high degree of expanded graphite nanosheets dispersion is achieved with and without surface modification using in situ polymerization method. Moreover, the presence of immobilized polysulfide chains near the interface region of nanosheets is suggested as a possible reason for the observed increase in the number of semi-crystalline organic fractions in the structure of PEDS via EG nanosheets incorporation. In addition, the morphology of SDBS-modified-EG loaded nanocomposite shows a smoother fracture surface than unmodified-nanosheets reinforced nanocomposite. Therefore, more interactions between nanosheets and polysulfide chains are expected in the structure of unmodified-EG reinforced nanocomposite. Moreover, thermal resistance and degradation kinetics of prepared nanocomposites are studied using thermogravimetric analysis results and degradation activation energy calculations, respectively. The required activation energy for the degradation process of SDBS-EG loaded nanocomposite is about 140 kJ mol lower than the required degradation activation energy of unmodified-nanosheets reinforced nanocomposite. [ABSTRACT FROM AUTHOR]

Thermal properties of the silica/poly(2,6-dimethyl-1,4-phenylene oxide) films prepared via emulsion polymerized mixed matrix (EPMM) method are investigated, and the impact of the synthesis protocol on the silica content, compatibility between the organic and inorganic phases, and the thermal stability of these nanocomposites is studied. Two series of films, namely EPMM- 1S and EPMM- 2S, synthesized in one- and two-step process, respectively, with different combinations of surfactant and compatibilizer were prepared. The polymerization of the silica precursor in the films was confirmed by Si nuclear magnetic resonance, and its content was investigated by inductively coupled plasma mass spectroscopy analysis. Thermal properties of the EPMM films were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature ( T) of EPMM films was greater compared to the neat PPO film. However, an increase in T was not related to the concentration of silica in the film, but rather to the quality of dispersion of synthesized nanoparticles. Despite a lower inorganic loading, EPMM- 1S films had a greater T than EPMM- 2S films. On the other hand, both the decomposition temperature and the activation energy for the decomposition were directly related to the silica content in the EPMM films. In general, regardless of the synthesis protocol, the presence of compatibilizer (ethanol) leads to greater inorganic content and improved thermal properties of the EPMM films. [ABSTRACT FROM AUTHOR]

Exfoliated graphite nanoplatelets (GNP)/epoxy resin nanocomposites were prepared and tested, varying the amount of the filler content. Systems' morphology was investigated by means of scanning electron microscopy, while their thermal response was examined via differential scanning calorimetry (DSC). Broadband dielectric spectroscopy and dynamic mechanical thermal analysis were employed in order to characterize the produced systems. Static mechanical tests were also conducted at ambient. Reinforced systems exhibit improved performance under mechanical and electrical excitation. In particular, storage modulus increases systematically with GNP content. DSC results imply that glass transition temperature is not affected by the presence of GNP. Flexural modulus and storage modulus, as determined by static and dynamic mechanical tests, respectively, increased with filler content. Dielectric permittivity increases also systematically with GNP content. Recorded relaxation processes arise from the glass to rubber transition of the polymer matrix (α-mode), re-orientation of polar side groups of the polymer chains (β-mode), and interfacial polarization because of the accumulation of charges at the systems' interface. Finally, the energy storing efficiency of the nanocomposites enhances with reinforcing phase in the examined frequency and temperature range. Optimum performance corresponds to the nanocomposite with maximum GNP loading. [ABSTRACT FROM AUTHOR]

In this study, we investigate the effect of nano sized FeO nanoparticles on the mechanical and thermal properties of EVA/PCL-FeO composites. Composites were prepared using the melt mixing technique on a Rheomex mixer coupled to a single screw extruder. The fine dispersion of nano-FeO aggregates in the polymer matrices led to a significant improvement in the crystallinity, thermal and mechanical properties of EVA/PCL-FeO nanocomposites compared to that of native polymers due to improved interface bonding between the filler and the polymer matrix. Techniques such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Instron for mechanical properties were used to characterize nanocomposites samples. The results obtained from this investigation demonstrated that composite materials could be promising raw materials in industry. [ABSTRACT FROM AUTHOR]

Pristine multiwalled carbon nanotubes (MWCNTs) were impregnated in acrylonitrile butadiene rubber (NBR) using internal dispersion kneader and two roller mixing mill to investigate the effects of various nanotubes concentrations on the thermal transport/stability of rubber nanocomposites. Thermal conductivity ( λ) and thermal impedance ( R) measurement experimental setups were established according to ASTM E1225-99 and D5470-03. The 1 mass % addition of MWCNTs in the polymer matrix has enhanced R up to 44 % and reduced λ of the rubber nanocomposite up to 40 % compare to the base composite formulation. Thermal decomposition and differential thermal analyses of the fabricated composite specimens simulate that the thermal stability and endothermic capability are augmented with increasing the nanotubes contents in the host matrix. The progressive incorporations of carbon nanotubes into the rubber matrix have efficiently influenced the composite specimens regarding glass transition, crystallization, and melting temperatures including their specific enthalpies. Scanning electron microscopy along with the energy dispersive spectroscopy was used to analyze MWCNTs dispersion in NBR matrix, compositional analysis of the nanocomposite, and impregnated nanotubes. [ABSTRACT FROM AUTHOR]

The paper concerns thermal properties of epoxy/nanotubes composites for aircraft application. In this work, influence of carbon nanotubes on thermal stability, thermal conductivity, and crosslinking density of epoxy matrix was determined. Three kinds of nanotubes were used: non-modified with 1- and 1.5-μm length, and 1-μm length modified with amino groups. Scanning electron microscopy observations were done for examining dispersion of nanotubes in the epoxy matrix. Glass transition temperature ( T) was readout from differential scanning calorimetry. From dynamic mechanical analysis, crosslinking density was calculated for epoxy and its composites. Also, thermogravimetric analysis was done to determine influence of nanotubes addition on thermal stability and decomposition process of composites. Activation energy was calculated from TGA curves by Flynn-Wall-Ozawa method. Thermal diffusivity was also measured. SEM images proved the uniform dispersion of carbon nanotubes without any agglomerates. It was found that nanotubes modified with amino groups lead to the increase of epoxy matrix crosslinking density. The significant increase in T was also observed. On the other hand, addition of carbon nanotubes leads to the decrease of thermal stability of polymer due to the increase of thermal diffusivity. [ABSTRACT FROM AUTHOR]

This article presents the results of investigation into receiving amide modification agents of smectic clays, used as nanofillers in polymer nanocomposites. Prepared materials were obtained on the base of terephthalic and isophthalic acids and simple aliphatic amines. Such structure makes them good layered silicates modifying agents as well as makes them well affiliate to structure of polymers containing aromatic, carbonyl, amide, etc. groups. Obtained compounds were introduced into clays' structure in protonated form, according to formulated method. Conducted research confirmed that the modification of montmorillonite clay (MMT) with received compounds had taken place. In order to establish that fact elementary analysis and X-ray diffraction (XRD) methods were used. Modificator molecules must display thermal resistance in full range of polymer processing temperatures. To investigate these properties the Thermogravimetric analysis (TG) of obtained compounds was carried out. These studies indicate that among the obtained compounds there were the ones with thermal stability over 523 K. Thermal resistance makes it possible for these substances to be used in poly(ethylene terephthalate) processing. [ABSTRACT FROM AUTHOR]

The objective of this work is to study the sintering behavior of polyamide 6 (PA6) powders and PA6 nanocomposites by means of thermomechanical (TMA) and dimensionless analysis in view of its technological application in rotational molding. TMA analysis was used to monitor the bulk density evolution of PA6 powders and PA6 nanocomposites when heated above the melting temperature. Experimental TMA results indicate that the sintering of PA6 and PA6 nanocomposites occurs in two different steps, namely powder coalescence and void removal. Furthermore, TMA analysis showed that relevant degradation phenomena occur during the sintering of PA6 and PA6 nanocomposites, leading to gas formation in the molten polymer. The suitability of these materials in rotational molding was then assessed by defining a processing window, as the temperature difference between the endset sintering and the onset degradation. The heating rate dependence of the processing window was explained by means of dimensionless analysis, showing that powder coalescence is influenced by the viscosity evolution of the matrix, whereas void removal is influenced by the gas diffusivity inside the molten matrix. Therefore, the diffusion activation energy correlates the endset sintering temperature to the heating rate. On the other hand, the onset degradation temperature depends on the heating rate, due to the characteristic activation energy of the degradation process. Accordingly, the width of the processing window mainly depends on the values of the activation energies for diffusivity and degradation. The width of the processing window for neat PA6 was found to be too narrow to candidate this polymer for rotational molding. The addition of nanofiller causes a narrowing of the processing window, whereas the PA6 matrix modified with a thermal stabilizer showed a sufficiently broad processing window, compatible for use in rotational molding. [ABSTRACT FROM AUTHOR]

High-density polyethylene-based nanocomposites were prepared through a melt compounding process by using surface functionalized fumed silica nanoparticles in various amounts, in order to investigate their capability to improve both mechanical properties and resistance to thermal degradation. The fine dispersion of silica aggregates led to noticeable improvements of both the elastic modulus and of the stress at yield proportionally to the filler content, while the tensile properties at break were not impaired even at elevated filler content. Thermogravimetric analysis showed that the selected nanoparticles were extremely effective both in increasing the decomposition temperature and in decreasing the mass loss rate, even at relatively low filler loadings. The formation of a char enriched layer, limiting the diffusion of the oxygen through the nanofilled samples, was responsible of noticeable improvements of the limiting oxygen index, especially at elevated silica loadings. In contrast with commonly reported literature results, cone calorimeter tests also revealed the efficacy of functionalized nanoparticles in delaying the time to ignition and in decreasing the heat release rate values. Therefore, the addition of functionalized fumed silica nanoparticles could represent an effective way to enhance the flammability properties of polyolefin matrices even at low filler concentrations. [ABSTRACT FROM AUTHOR]

The aim of this article is to develop nano-scale composite fibers from wood pulp, modified wood pulp, and polyethylene oxide (PEO). Composite fibers were developed in the diameter range of 339-612 nm. Alignment process of the composite fibers was done by electrostatic interactions between two collector disks. DSC results demonstrated a lower melting temperature of composite fibers than PEO powder. The development of crystalline structure in the composite fibers and acetylated wood pulp was poor. Thermogravimetric analysis revealed that the thermal stability of composite fibers were relatively lower than PEO powder. Fourier transform infrared spectroscopy (FTIR) showed significant differences between modified and unmodified wood pulp in the region of 960-1746 cm. The peak intensity of acetylated wood pulp was appeared at 1746 cm because of acetyl groups. The composite fibers demonstrated the characteristic peak of PEO since less wood pulp was incorporated in the composite system. [ABSTRACT FROM AUTHOR]

In this study, we have studied the stability of TiO-CdSe nanocomposites in which the individual moieties are linked using a bifunctional linker (mercaptopropionic acid). Nanoparticles of TiO and CdSe are synthesized by sol-gel and one pot methods. The equimolar amount of the above particles is utilized to prepare nanocomposites with and without linker. These samples are characterized for their structural, thermal, and optical properties using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis (TG), Fourier transform infra-red spectroscopy (FTIR), and UV-Vis spectroscopy. The average particle size of TiO and CdSe are 16 and 23 nm, respectively. The addition of a bifunctional linker shows remarkable effect on the properties of TiO-CdSe nanocomposites. [ABSTRACT FROM AUTHOR]

Thermal properties of sodium alginate and calcium alginate fibres containing nanoadditives were analysed. Thermal decomposition of fibres based on sodium alginate, both pure and containing nanoadditive, produces sodium carbonate (for fibres without nanoadditive) or, for modified fibres, a mixture of sodium carbonate with the corresponding nanoadditive, which does not undergo any changes within the range of measured temperatures. The chief gaseous products accompanying the decomposition are carbon (IV) oxide and water. The shape of the DTG curves and values of the * T coefficient indicate an improvement in the thermal properties of the fibres when ceramic nanoadditives (SiO and HAp) are introduced, as compared with pure sodium alginate fibres. When ceramic nanoadditives (MMT, SiO, bioglass) are added to the material of calcium alginate fibres the nature of the thermal processes is not affected. However, similarly as for sodium alginate fibres modified with nanoadditive, here also it was note the effect on the value of the * T coefficient. The greatest thermal stability, expressed by the value of * T, was observed when SiO, HAp and bioglass were used as nanoadditives. Considering that the porosity, sorption properties and cross section were similar for all fibres, it can be suggested that in all cases the structure of the fibres has a lesser effect than the type of nanoadditive on the thermal properties of the investigated fibres. The effect of the chemical structure of the material was reflected in the higher decomposition temperature of calcium alginate nanocomposite fibres compared with sodium alginate fibres. This also applies to fibres without any nanoadditive. [ABSTRACT FROM AUTHOR]

This paper is devoted to the investigation of the properties of the natural rubber composites prepared using the cation exchanged-montmorillonite fillers. The characteristics of the montmorillonite fillers were studied by Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). These characterized fillers were used to preparation of the natural rubber composites, which were submitted to measurements of dynamic-mechanical thermal analysis (DMTA) and vulcanizing characteristics ( M, M, t, t, R) as well as physico-mechanical properties (tensile strength, modulus at 300 elongation- M, tensibility). [ABSTRACT FROM AUTHOR]

Phase change nanocomposites were prepared by dispersing γ-AlO nanoparticles into melting paraffin wax (PW). Intensive sonication was used to make well dispersed and homogeneous composites. Differential scanning calorimetric (DSC) and transient short-hot-wire (SHW) method were employed to measure the thermal properties of the composites. The composites decreased the latent heat thermal energy storage capacity, L, and melting point, T, compared with those of the PW. Interestingly, the composites with low mass fraction of the nanoparticles, have higher latent heat capacity than the calculated latent heat capacity value. The thermal conductivity of the nanocomposites was enhanced and increased with the mass fraction of AlO in both liquid state and solid state. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid composites of epoxy and phenyltrisilanol polyhedral oligomeric silsesquioxane (Ph7Si7O9(OH)3, POSS-triol) were prepared via in situ polymerization of epoxy monomers. The nanocomposites of epoxy with POSS-triol can be prepared in the presence of metal complex latent catalyst, aluminum triacetylacetonate ([Al]) for the reaction between POSS-triol and diglycidyl ether of bisphenol A (DGEBA). The dispersion morphology of organic–inorganic hybrid was characterized by scanning electronic microscopy (SEM). The thermostability of composites was evaluated by thermal gravimetric (TG) analysis. The flammability was evaluated by cone calorimeter test. The presence of [Al] latent catalyst leads to a decrease in combustion rate with respect to epoxy and epoxy/POSS composites as well as reduction in smoke, CO and CO2 production rate. The effect of [Al] is to reduce the size of spherical POSS particles from 3–5 μm in epoxy/POSS to 0.5 μm in epoxy/POSS[Al]. Furthermore, POSS with smaller size may form compact and continue char layer on the surface of composites more efficiently. [ABSTRACT FROM AUTHOR]