Tufting has been shown to improve the mechanical properties of composites. Unlike other published works which rely on commercially available materials, for this study, continuous polymer yarns with diameters ranging from 160 μm to 720 μm of unfilled PPSU and PPSU nanocomposites with 1 wt.% of carbon nanotubes (CNT) were prepared using a twin-screw extruder. The tensile properties of these yarns generally improved with the addition of CNT at higher values of ‘screw speed to haul-off’ ratio. This effect is correlated with the yarn draw down ratio and attributed to the nanofiller orientation induced in the thermoplastic matrix. The fibres exhibited as much as a 23% increase in Ultimate Tensile Strength (UTS) for the same parameter set when loaded with CNT. Depending on filler and processing parameters set, yarns varied in UTS from 96.4 MPa to 206.2 MPa for unfilled PPSU and PPSU-CNT, respectively.

Improvement of the mechanical properties of FFF 3D printed CF/PEEK composites was achieved by printing under favorable crystallization conditions. It was possible to improve the layer-layer tensile strength more than fivefold from 6.96 MPa to 36.28 MPa by printing in a specially customised, low cost printer operated with a heated print chamber at 230 . The influence of the chamber temperature on the mechanical and crystalline structure was investigated to determine the best conditions. A maximum flexural modulus of 14 946 MPa and flexural stress at break of 248.9 MPa were achieved. A proof of concept study involved the 3DP of a CF/PEEK mould tooling insert for injection moulding. This insert replaced a costly traditional metal insert to print short production runs of ABS and HIPS polymers. This work offers a low cost and rapid means to produce effective tooling inserts for the injection moulding industry.

Successful printing of high-performance material with suitable properties using additive manufacturing methods such as Fused Filament Fabrication (FFF) can create many advanced applications in industries. However, the high viscosity of high-performance polymers causes complications during the FFF process and reduces the final print quality. To overcome this challenge, Inorganic Fullerene Tungsten Sulphide (IF-WS2) nanoparticles are applied in this study to enhance the flowability of poly-ether-ketone-ketone (PEEK) without compromising its mechanical and thermal properties. In the first step, different loadings of IF-WS2 nanoparticles are melt compounded with PEEK and the nanocomposites are characterized. SEM and EDX images of fractured surfaces indicate that a good dispersion of nanoparticles is achieved without any pre-treatment or pre-dispersion. A reduction in melt viscosity of 25%, and a simultaneous growth in storage modulus, crystallization and degradation temperature of about 60%, 53% and 100 degrees C is found with addition of 2 wt% IF-WS2 to PEEK, respectively. This great achievement is mainly ascribed to the unique characteristics of IF-WS2 nanoparticles, acting as both reinforcing and lubricating agents, indicated by a reduction in coefficient of friction. There is no significant increase of crystallization and melting temperatures with the addition of IF-WS2 nanoparticles, which is beneficial in the FFF process. In the second step, the PEEK nanocomposite filaments are printed via FFF. The print quality and mechanical properties of the printed PEEK are also improved with the incorporation of IF-WS2 nanoparticles. Hence, incorporation of IF-WS2 nanoparticles into PEEK via melt compounding is an effective approach for the development of suitable high-performance engineering materials for FFF.

Yarn diameters ranging from 160 µm to 720 µm of unfilled PPSU and PPSU nanocomposites with 1 wt.% of either carbon nanotubes (CNT) or carbon nanofibers (CNF) were prepared using a twin screw compounder. The tensile properties of these yarns generally improve with the addition of CNT or CNF at higher values of screw speed-to-haul off ratio. This effect is correlated with the yarn draw down ratio and attributed to nanofiller orientation and crystallinity induced in thermoplastic matrix. The fibres have as much as a 23% increase in Ultimate Tensile Strength (UTS) for the same parameter set when loaded with CNT, while the greatest increase observed for larger particle size fillers CNF is just 3.77%. Depending on filler and processing parameters set, yarns varied in UTS from 24.84MPa to 206.23MPa for unfilled PPSU and PPSU-CNT, respectively.Yarn diameters ranging from 160 µm to 720 µm of unfilled PPSU and PPSU nanocomposites with 1 wt.% of either carbon nanotubes (CNT) or carbon nanofibers (CNF) were prepared using a twin screw compounder. The tensile properties of these yarns generally improve with the addition of CNT or CNF at higher values of screw speed-to-haul off ratio. This effect is correlated with the yarn draw down ratio and attributed to nanofiller orientation and crystallinity induced in thermoplastic matrix. The fibres have as much as a 23% increase in Ultimate Tensile Strength (UTS) for the same parameter set when loaded with CNT, while the greatest increase observed for larger particle size fillers CNF is just 3.77%. Depending on filler and processing parameters set, yarns varied in UTS from 24.84MPa to 206.23MPa for unfilled PPSU and PPSU-CNT, respectively.

The currently limited comprehension of hierarchical control over out-of-equilibrium (dynamic) self-assembly processes in nanoscience and nanotechnology has limited the exploitation of multicomponent systems in the design of new nanostructured functional materials. In this study's contribution, molecular building blocks with tailored nanoscale anisotropic supramolecular self-assembly behavior enable the creation of mesoscale percolation networks of multiwalled carbon nanotubes through collinear interconnections at the microscale. This strategy affords polymeric composites with tunable properties at the macroscale, where the organization mechanism is regulated by dynamic self-assembly at 4 hierarchical levels of auto-organization. Such multilevel self-assembly system reduces up to eightfolds the nanotube concentration required for percolation and enhances conductivity up to 6 orders of magnitude against blanks, thus yielding anisotropically semiconducting and conducting materials. The approach is based on casting-from-solution, thus simplifying preparative steps when compared to state-of-the-art electron carrier counterparts such as single-walled carbon nanotube-, graphene-, or indium-tin-oxide-based technologies. Finally, promising material transparency levels can be reached across the visible and near-infrared regimes for compositions above the percolation threshold, which provides new opportunities beyond the current spectral restrictions in commercial transparent conductors.

ABSTRACTIn this work, we present thermoplastic nanocomposites of polycarbonate (PC) matrix with hybrid nanofillers system formed by a melt‐mixing approach. Various concentrations of multi‐walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GnP) were mixed in to PC and the melt was homogenized. The nanocomposites were compression molded and characterized by different techniques. Torque dependence on the nanofiller composition increased with the presence of carbon nanotubes. The synergy of carbon nanotubes and GnP showed exponential increase of thermal conductivity, which was compared to logarithmic increase for nanocomposite with no MWCNT. Decrease of Shore A hardness at elevated loads present for all investigated nanocomposites was correlated with the expected low homogeneity caused by a low shear during melt‐mixing. Mathematical model was used to calculate elastic modulus from Shore A tests results. Vicat softening temperature (VST) showed opposite pattern for hybrid nanocomposites and for PC‐MWCNT increasing in the latter case. Electrical conductivity boost was explained by the collective effect of high nanofiller loads and synergy of MWCNT and GnP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42536.

ABSTRACTIn this work, nanocomposites of polycarbonate/acrylonitrile‐butadiene‐styrene (PC/ABS) with various loads of multiwall carbon nanotubes (MWCNT) are investigated. Material is previously formed by masterbatch dilution approach and further processed by injection molding at various velocities. Microscopic characterization of nanocomposites morphology reveals stronger dependence of MWCNT dispersion on processing parameters at higher nanofiller load. Dispersion of carbon nanotubes at various distances from the injection gate is studied by Raman spectroscopy showing lower deviation at elevated injection velocity. Nanoindentation results that are in agreement with uniaxial tensile testing show a slight decrease of nanocomposites' mechanical performance at 3.0 wt % MWCNT in samples injected at reduced velocity. This is explained by the increase of agglomeration behavior at these conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42014.

In this study, nanocomposites of polypropylene (PP) with various loadings of multi-wall carbon nanotubes (MWCNT) and graphene nanoplatelets (GnP) were formed by masterbatch dilution/mixing approach from individual masterbatches PP-MWCNT and PP-GnP. Melt mixing on a twin-screw extruder at two different processing temperatures was followed by characterization of morphology by transmitted-light microscopy including the statistical analysis of agglomeration behavior. The influence of processing temperature and weight fractions of both nanofillers on the dispersion quality is reported. Thermal properties of the nanocomposites investigated by DSC and TGA show sensitivity to the nanofillers weight fraction ratio and to processing conditions. Electrical conductivity is observed to increase up to an order of magnitude with the concentration of each nanofiller increasing from 0.5 wt % to 1.0 wt %. This is related with a decrease of electrical conductivity observed for unequal concentration of both nanofillers. This particular behavior shows the increase of electrical properties for higher MWCNT loadings and the increase of thermo-mechanical properties for higher GnP loadings. (c) 2015 Wiley Periodicals, Inc.

En les mostres processades mitjançant masterbatch es va observar que la rigidesa augmentava per damunt del 30 %, alhora que es reduïa la ductilitat del PC/ABS.Per a addicions del 0.5 % en pes de MWCNT.Així mateix, es va observar que els valors de conductivitat elèctrica estaven influenciats per les temperatures de processament i la naturalesa dels nanotubs de carboni, sent el valor de percolació del 2.0 % en pes per als MWCNT purs i del 1.5 % en pes per als MWCNT-COOH. viAtenent al millor balanç de propietats mecàniques i de conductivitat elèctrica aconseguit en les mostres obtingudes mitjançant la ruta de masterbatch, en una següent fase es va estudiar la variació produïda en aquestes propietats quan el nanocompost extrudit va ser modelat per injecció per a obtenir una geometria definida.De l'estudi dels paràmetres d'injecció es va observar que les mostres injectades presentaven una major homogeneïtat, i per tant una major conductivitat elèctrica, quan s'aplicaven baixes velocitats d'injecció i temperatures intermèdies de fos.Aquest efecte està relacionat amb la major orientació dels nanotubs de carboni en les zones internes amb major concentració de MWCNT i a l'existència d un efecte de pell.Malgrat açò, la conductivitat eléctrica màxima aconseguida després del procés d'injecció es va reduir diversos ordres de magnitud respecte al valor obtingut en l'etapa prèvia de compounding.Finalment, es va dur a cap un modelitzat matemàtic de l'orientació produïda en els nanotubs de carboni durant el procés de moldeig per injecció, i els resultats obtinguts van mostrar un bon ajust amb els valors experimentals.Es va observar una alta orientació dels nanotubs de carboni en la direcció del flux a distàncies allunyades del punt d'injecció, amb valors teòrics per damunt del 75 %, així com una pèrdua de l´orientació en les proximitats del punt d'injecció degut a pertorbacions en el flux.viii

Molecular electronics based on structures ordered as neural networks emerges as the next evolutionary milestone in the construction of nanodevices with unprecedented applications. However, the straightforward formation of geometrically defined and interconnected nanostructures is crucial for the production of electronic circuitry nanoequivalents. Here we report on the molecularly fine-tuned self-assembly of tetrakis-Schiff base compounds into nanosized rings interconnected by unusually large nanorods providing a set of connections that mimic a biological network of neurons. The networks are produced through self-assembly resulting from the molecular conformation and noncovalent intermolecular interactions. These features can be easily generated on flat surfaces and in a polymeric matrix by casting from solution under ambient conditions. The structures can be used to guide the position of electron-transporting agents such as carbon nanotubes on a surface or in a polymer matrix to create electrically conducting networks that can find direct use in constructing nanoelectronic circuits.

ABSTRACTThe influence of injection molding parameters on electrical properties and morphology of PC/ABS‐MWCNT nanocomposites is presented in this article. Investigation is based on the masterbatch of 5.0 wt % carbon nanotubes obtained by melt‐mixing. Further processing includes dilution of this nanocomposite to desired concentrations on twin‐screw extruder and injection molding or direct dilution of masterbatch in injection molding. Additionally, reprocessing of materials formed by compression and injection molding is presented along with the change in electrical conductivity. Morphology differs strongly between the two processing paths showing change in agglomeration behavior between nanotubes concentrations. Electrical properties show dependence on injection velocity and melt temperature in both applied processing paths. Moreover, electrical conductivity recovery is proved after injection and compression molding. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2152–2158, 2013

Nanocomposites of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) with multiwall carbon nanotubes (MWCNT) prepared by masterbatch dilution are investigated in this work. Melt compounding with twin screw extruder is followed by complete characterization of morphology, rheological-, mechanical-, and thermal-properties of the nanocomposites. Light-transmission- and scanning electron microscopy shows the preferential location of MWCNT in the PC. Nevertheless, relatively good dispersion in the whole matrix is achieved, what is corroborated with the specific mechanical energy. The study of viscoelastic properties of PC/ABS-MWCNT shows the fluid-solid transition below 0.5 wt % MWCNT. Beyond this point the continuous nanofiller network is formed in the matrix promoting the reinforcement. Addition of 0.5 wt % MWCNT reduces ductility of PC/ABS and enhances Young's modulus by about 30% and yield stress by about 20%. Moreover, theoretical values of stiffness calculated within this work agree with the experimental data. Electrical conductivity, showing percolation at 2.0 wt % MWCNT, are influenced by processing temperature. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40271.

4 wt% multiwalled carbon nanotubes (MWCNTs) were incorporated into a miscible blend of polyphenylenether/polystyrene (PPE/PS) on a twin-screw extruder at a screw speed of 600 rpm. The masterbatch obtained was diluted at 400 and 600 rpm to obtain lower MWCNT loadings in PPE/PS. Electron microscopy & optical microscopy images show very good MWCNT dispersion even at high filler loadings of 4 wt%, but slightly larger agglomerate size fractions are observable at higher screw speeds. While MWCNT addition enhanced the thermal stability of PPE/PS, a small change in glass transition was observed on the composites at different filler concentrations compared to PPE/PS. The specific heat capacity at glass transition decreases considerably until 2 wt% MWCNT and levels down thereafter for both processing conditions pointing to enhanced filler-matrix interaction at lower loadings. Storage modulus of the nanocomposites was enhanced significantly on MWCNT incorporation with reinforcing effect dropping considerably as a function of temperature, especially at lower filler contents. The modulus and the tensile strength of PPE/PS were only marginally enhanced in spite of excellent MWCNT dispersion in the matrix. Electrical percolation occurs at 0.4 wt% MWCNT content, and the electrical conductivity of 0.5 wt% MWCNT reinforced PPE/PS was close to 12 orders in magnitude higher compared to PPE/PS.

Summary: Nanocomposites of commercial PC/ABS matrix filled with multi-walled carbon nanotubes (MWCNT) suspended in ethyl alcohol were compounded on twin-screw co-rotating extruder and subsequently injection molded varying injection speed and temperature. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to characterize the morphology of nanocomposites. A presence of fine agglomerates of carbon nanotubes was observed. The elastic modulus and stress at yield point increased with MWCNT content for all nanocomposites. However, higher values of yield stress were obtained for lower injection velocities, due to more homogeneous dispersion at mild injection molding conditions.

Reaction of [PtCl(2)(dmso)(2)] with 2,5-(dialkoxyphenyl)pyridine in HOAc leads to a dinuclear, acetate-bridged, metal-metal bonded complex of platinum(III); dmso in the presence of acid is found to be responsible for the oxidation. The dimer is analogous structurally to Pd(III) dimers implicated in catalytic acetoxylation. Platinum dimers with longer alkoxy chains are shown to be unique examples of liquid crystals of platinum(III).

Two series of novel symmetrical azomethines prepared by the condensation of 4,4′-(butane-1,4-diylbis(oxy))bis(butane-4,1-diyl)bis(4-aminobenzoate) (PBBA470) and 5,10,15,20,25,30,35,40,45,50,55,60-dodecaoxatetrahexacontane-1,64-diylbis(4-aminobenzoate) (PBBA 1200) with a range of aldehydes have been characterised by 1H and 13C nuclear magnetic resonance, Fourier transform infrared and UV–Vis spectroscopy. Current–voltage measurements were performed using a device comprising indium–tin oxide/compound/Alq3/Al. The effect of rod length and the nature of the terminal chains on the thermal and mesomorphic behaviour of these materials were investigated by differential scanning calorimetry, polarising optical microscopy and wide- and small-angle X-ray diffraction. Additionally, the compounds were studied using various atomic force microscopy techniques, including mode and phase imaging, and measurements based on local contrast force–distance curves and roughness, together with skew and kurtosis, are presented.

Polymers have been prepared by the polycondensation of 4,4'-(butane-1,4-diylbis(oxy)) bis(butane-4,1-diyl) bis(4-aminobenzoate) and 5,10,15,20,25,30,35,40,45,50,55,60-dodecaoxatetrahexacontane-1,64-diyl bis(4-aminobenzoate) (PBBA 1200) with three dianhydrides based on naphthalene, perylene and phthalic moieties, respectively. This has resulted in five novel aliphatic-aromatic polyimides. The polyimides differed in aliphatic chain length and whether the imide ring was five- or six-membered. The chemical structure of the polyimides has been confirmed by 1H NMR and FTIR spectroscopy and by elemental analysis. The optical and electrical properties of the polyimides have been studied using current-voltage measurements, and the effect of the polyimide structure on thermal and mesomorphic behaviour investigated by differential scanning calorimetry and polarising optical microscopy. Wide-angle X-ray diffraction at different temperatures was employed to confirm the structural properties of the polyimides. All the novel polyimides, with the sole exception of that obtained from PBBA1200 and 3,4,9,10-perylenetetracarboxylic dianhydride, showed liquid crystalline properties. As far as we are aware, this is the first time that six-membered polyimides exhibiting liquid crystalline properties have been reported.

Lead-free Na0.5K0.5NbO3 (NKN) and Na0.475K0.475Li0.05NbO3 (NKLN) ceramics doped with CuO were prepared by the mixed oxide route. The powders were calcined at 850–930°C and sintered at 850–1100°C. Small additions of CuO reduced the sintering temperature and increased the density to 96% theoretical. Cu first appears to enter the A site then the B site. In NKLN the orthorhombic–tetragonal and tetragonal–cubic phase transitions are approximately 150°C lower and 50°C higher, respectively than in NKN. With increasing addition of Cu to NKN and NKLN the remanent polarization (Pr) increased and coercive field (Ec) decreased. NKLN prepared with 0.4wt% CuO exhibited a saturation polarization (Psat) of 30μC/cm2, remanent polarization (Pr) of 27μC/cm2 and coercive field (Ec) of 1.0kV/mm. CuO caused the NKLN ceramics to harden considerably; the mechanical quality factor (Qm) increased from 50 to 260, d33∼285 and piezoelectric coupling factors were >0.4.

AbstractThe method for reactive lysine determination, developed by HURREL et al. (1975) is adopted to the utilization of azo dye Orange G. Lysine content in cereals can be determined using Orange G solution instead of Acid Orange 12 solution, provided that the new buffer system is secured. The results obtained with both the procedures prove to be consistent with each other. All analyses can give satisfactory results applying ordinary laboratory equipment.