scholarly journals Melt-Spun Nanocomposite Fibers Reinforced with Aligned Tunicate Nanocrystals

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1912 ◽  
Author(s):  
Alexandre Redondo ◽  
Sourav Chatterjee ◽  
Pierre Brodard ◽  
LaShanda T. J. Korley ◽  
Christoph Weder ◽  
...  
Keyword(s):  
Melt Spinning ◽  
Thermoplastic Polyurethane ◽  
Tensile Tests ◽  
Nanocomposite Films ◽  
Fiber Direction ◽  
Melt Mixing ◽  
Young’S Moduli ◽  
Twin Screw ◽  
Order Of Magnitude ◽  
Phosphoric Acid Hydrolysis

The fabrication of nanocomposite films and fibers based on cellulose nanocrystals (P-tCNCs) and a thermoplastic polyurethane (PU) elastomer is reported. High-aspect-ratio P-tCNCs were isolated from tunicates using phosphoric acid hydrolysis, which is a process that affords nanocrystals displaying high thermal stability. Nanocomposites were produced by solvent casting (films) or melt-mixing in a twin-screw extruder and subsequent melt-spinning (fibers). The processing protocols were found to affect the orientation of both PU hard segments and the P-tCNCs within the PU matrix and therefore the mechanical properties. While the films were isotropic, both the polymer matrix and the P-tCNCs proved to be aligned along the fiber direction in the fibers, as shown using SAXS/WAXS, angle-dependent Raman spectroscopy, and birefringence analysis. Tensile tests reveal that fibers and films, at similar P-tCNC contents, display Young’s moduli and strain-at-break that are within the same order of magnitude, but the stress-at-break was found to be ten-times higher for fibers, conferring them a superior toughness over films.

scholarly journals Using an Ionic Liquid to Reduce the Electrical Percolation Threshold in Biobased Thermoplastic Polyurethane/Graphene Nanocomposites

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 435 ◽  
Author(s):  
Nora Aranburu ◽  
Itziar Otaegi ◽  
Gonzalo Guerrica-Echevarria
Keyword(s):  
Ionic Liquid ◽  
Percolation Threshold ◽  
Thermoplastic Polyurethane ◽  
Melt Mixing ◽  
Graphene Nanocomposites ◽  
Electrical Percolation ◽  
Twin Screw ◽  
Electrical Percolation Threshold ◽  
A Minor ◽  
Positive Effect

Biobased thermoplastic polyurethane (bTPU)/unmodified graphene (GR) nanocomposites (NCs) were obtained by melt-mixing in a lab-scaled conventional twin-screw extruder. Alternatively, GR was also modified with an ionic liquid (GR-IL) using a simple preparation method with the aim of improving the dispersion level. XRD diffractograms indicated a minor presence of well-ordered structures in both bTPU/GR and bTPU/GR-IL NCs, which also showed, as observed by TEM, nonuniform dispersion. Electrical conductivity measurements pointed to an improved dispersion level when GR was modified with the IL, because the bTPU/GR-IL NCs showed a significantly lower electrical percolation threshold (1.99 wt%) than the bTPU/GR NCs (3.21 wt%), as well as higher conductivity values. Young’s modulus increased upon the addition of the GR (by 65% with 4 wt%), as did the yield strength, while the ductile nature of the bTPU matrix maintained in all the compositions, with elongation at break values above 200%. This positive effect on the mechanical properties caused by the addition of GR maintained or slightly increased when GR-IL was used, pointing to the success of this method of modifying the nanofiller to obtain bTPU/GR NCs.

Behaviour of PLA/POSS nanocomposites: Effects of filler content, functional group and copolymer compatibilization

2021 ◽  
pp. 096739112110080
Author(s):  
Yelda Meyva Zeybek ◽  
Cevdet Kaynak
Keyword(s):  
Functional Group ◽  
Filler Content ◽  
Mechanical And Thermal Properties ◽  
Screw Extruder ◽  
Melt Mixing ◽  
Grafted Copolymer ◽  
Before And After ◽  
Twin Screw ◽  
Oligomeric Silsesquioxane ◽  
Matrix Nanocomposites

The main purpose of this study was to investigate influences of three parameters on the mechanical and thermal properties of the polylactide (PLA) matrix nanocomposites filled with polyhedral oligomeric silsesquioxane (POSS) particles. For the first parameter of “Filler Content”, nanocomposites with 1, 3, 5, 7 wt% basic POSS structure were compared. For the second parameter of “Functional Group,” basic POSS structure having only nonpolar isobutyl groups were compared with three other functionalized POSS structures; i.e. aminopropylisobutyl-POSS (ap-POSS), propanediolisobutyl-POSS (pd-POSS) and octasilane-POSS (os-POSS). Finally, for the third parameter of “Copolymer Compatibilization,” all specimens were compared before and after their maleic anhydride (MA) grafted copolymer compatibilization. Specimens were produced with twin-screw extruder melt mixing and shaped under compression molding. Various tests and analyses indicated that the optimum filler content for the improved mechanical properties was 1 wt%; while the optimum structure for strength and modulus was pd-POSS structure, in terms of fracture toughness it was basic POSS structure. Additional use of MA compatibilization was especially effective for the basic POSS and os-POSS particles.

scholarly journals Preparation and Characterization of Transparent Polyimide Nanocomposite Films with Potential Applications as Spacecraft Antenna Substrates with Low Dielectric Features and Good Sustainability in Atomic-Oxygen Environments

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1886
Author(s):  
Yan Zhang ◽  
Bo-han Wu ◽  
Han-li Wang ◽  
Hao Wu ◽  
Yuan-cheng An ◽  
...  
Keyword(s):  
Atomic Oxygen ◽  
Composite Films ◽  
Dissipation Factor ◽  
Low Earth Orbit ◽  
Nanocomposite Films ◽  
Dielectric Parameters ◽  
Low Dielectric ◽  
Aerospace Applications ◽  
Optically Transparent ◽  
Order Of Magnitude

Optically transparent polyimide (PI) films with good dielectric properties and long-term sustainability in atomic-oxygen (AO) environments have been highly desired as antenna substrates in low earth orbit (LEO) aerospace applications. However, PI substrates with low dielectric constant (low-Dk), low dielectric dissipation factor (low-Df) and high AO resistance have rarely been reported due to the difficulties in achieving both high AO survivability and good dielectric parameters simultaneously. In the present work, an intrinsically low-Dk and low-Df optically transparent PI film matrix, poly[4,4′-(hexafluoroisopropylidene)diphthalic anhydride-co-2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane] (6FPI) was combined with a nanocage trisilanolphenyl polyhedral oligomeric silsesquioxane (TSP-POSS) additive in order to afford novel organic–inorganic nanocomposite films with enhanced AO-resistant properties and reduced dielectric parameters. The derived 6FPI/POSS films exhibited the Dk and Df values as low as 2.52 and 0.006 at the frequency of 1 MHz, respectively. Meanwhile, the composite films showed good AO resistance with the erosion yield as low as 4.0 × 10−25 cm3/atom at the exposure flux of 4.02 × 1020 atom/cm2, which decreased by nearly one order of magnitude compared with the value of 3.0 × 10−24 cm3/atom of the standard PI-ref Kapton® film.

scholarly journals Polyamide 6 and thermoplastic polyurethane recycled hybrid Fibres via twin-screw melt extrusion

2019 ◽  
Vol 26 (7) ◽  
Author(s):  
Siti Zaharah Kunchimon ◽  
Muhammad Tausif ◽  
Parikshit Goswami ◽  
Vien Cheung
Keyword(s):  
Thermoplastic Polyurethane ◽  
Polyamide 6 ◽  
Melt Extrusion ◽  
Twin Screw

Thermoplastic polyurethane/CNT nanocomposites with low electromagnetic resistance property

2021 ◽  
pp. 002199832110370
Author(s):  
Chia-Fang Lee ◽  
Chin-Wen Chen ◽  
Fu-Sheng Chuang ◽  
Syang-Peng Rwei
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Thermoplastic Polyurethane ◽  
Conductive Polymer ◽  
Resistance Coefficient ◽  
Equal Weight ◽  
Mechanical And Thermal Properties ◽  
Multi Wall Carbon Nanotubes ◽  
Twin Screw ◽  
Acrylic Ester

Multi-wall carbon nanotubes (MWCNTs) at 0.5 wt% to 2 wt% proportions were added to thermoplastic polyurethane (TPU) synthesized with polycarbonatediol (PCDL), 4,4’-methylene diphenyl diisocyanate (MDI), and 1,3-butanediol(1,3-BDO). To formulate a new TPU-MWCNT nanocomposite, the composite was melt-blended with a twin-screw extruder. To ensure the even dispersion of MWCNTs, dispersant (ethylene acrylic ester terpolymer; Lotader AX8900) of equal weight proportion to the added MWCNTs was also added during the blending process. Studies on the mechanical and thermal properties, and melt flow experiments and phase analysis of TPU-MWCNT nanocomposites, these nanocomposites exhibit higher tensile strength and elongation at break than neat TPU. TPU-MWCNT nanocomposites with higher MWCNT content possess higher glass-transition temperature (Tg), a lower melt index, and greater hardness. Relative to neat TPU, TPU-MWCNT nanocomposites exhibit favorable mechanical properties. By adding MWCNTs, the tensile strength of the nanocomposites increased from 7.59 MPa to 21.52 MPa, and Shore A hardness increased from 65 to 81. Additionally, TPU-MWCNT nanocomposites with MWCNTs had lower resistance coefficients; the resistance coefficient decreased from 4.97 × 1011 Ω/sq to 2.53 × 104 Ω/sq after adding MWCNTs, indicating a conductive polymer material. Finally, the internal structure of the TPU-MWCNT nanocomposites was examined under transmission electron microscopy. When 1.5 wt% or 2 wt% of MWCNTs and dispersant were added to TPU, the MWCNTs were evenly dispersed, with increased electrical conductivity and mechanical properties. The new material is applicable in the electronics industry as a conductive polymer with high stiffness.

scholarly journals Filling of Mater-Bi with Nanoclays to Enhance the Biofilm Rigidity

2018 ◽  
Vol 9 (4) ◽  
pp. 60 ◽  
Author(s):  
Giuseppe Cavallaro ◽  
Giuseppe Lazzara ◽  
Lorenzo Lisuzzo ◽  
Stefana Milioto ◽  
Filippo Parisi
Keyword(s):  
Tensile Properties ◽  
Food Packaging ◽  
Mechanical Response ◽  
Materials Science ◽  
Traction Force ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Nanocomposite Films ◽  
Preliminary Study ◽  
Mechanical Performances

We investigated the efficacy of several nanoclays (halloysite, sepiolite and laponite) as nanofillers for Mater-Bi, which is a commercial bioplastic extensively used within food packaging applications. The preparation of Mater-Bi/nanoclay nanocomposite films was easily achieved by means of the solvent casting method from dichloroethane. The prepared bio-nanocomposites were characterized by dynamic mechanical analysis (DMA) in order to explore the effect of the addition of the nanoclays on the mechanical behavior of the Mater-Bi-based films. Tensile tests found that filling Mater-Bi with halloysite induced the most significant improvement of the mechanical performances under traction force, while DMA measurements under the oscillatory regime showed that the polymer glass transition was not affected by the addition of the nanoclay. The tensile properties of the Mater-Bi/halloysite nanotube (HNT) films were competitive compared to those of traditional petroleum plastics in terms of the elastic modulus and stress at the breaking point. Both the mechanical response to the temperature and the tensile properties make the bio-nanocomposites appropriate for food packaging and smart coating purposes. Here, we report a preliminary study of the development of sustainable hybrid materials that could be employed in numerous industrial and technological applications within materials science and pharmaceutics.

scholarly journals Size Distribution, Mechanical and Electrical Properties of CuO Nanowires Grown by Modified Thermal Oxidation Methods

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1051 ◽  
Author(s):  
Raitis Sondors ◽  
Jelena Kosmaca ◽  
Gunta Kunakova ◽  
Liga Jasulaneca ◽  
Matiss Martins Ramma ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Aspect Ratio ◽  
Electric Field ◽  
Thermal Oxidation ◽  
Size Distribution ◽  
High Aspect Ratio ◽  
Growth Conditions ◽  
Cuo Nanowires ◽  
Young’S Moduli ◽  
Order Of Magnitude

Size distribution, Young’s moduli and electrical resistivity are investigated for CuO nanowires synthesized by different thermal oxidation methods. Oxidation in dry and wet air were applied for synthesis both with and without an external electrical field. An increased yield of high aspect ratio nanowires with diameters below 100 nm is achieved by combining applied electric field and growth conditions with additional water vapour at the first stage of synthesis. Young’s moduli determined from resonance and bending experiments show similar diameter dependencies and increase above 200 GPa for nanowires with diameters narrower than 50 nm. The nanowires synthesized by simple thermal oxidation possess electrical resistivities about one order of magnitude lower than the nanowires synthesized by electric field assisted approach in wet air. The high aspect ratio, mechanical strength and robust electrical properties suggest CuO nanowires as promising candidates for NEMS actuators.

Shape Memory Characteristics and Superelasticity of Ti-Ni-Cu Alloy Ribbons with Nano Ti2Ni Particles

2008 ◽  
Vol 8 (2) ◽  
pp. 722-727 ◽  
Author(s):  
Tae-hyun Nam ◽  
Cheol-am Yu ◽  
Jung-min Nam ◽  
Hyun-gon Kim ◽  
Yeon-wook Kim
Keyword(s):  
Melt Spinning ◽  
Volume Fraction ◽  
Deformation Behaviour ◽  
Parent Phase ◽  
Tensile Tests ◽  
Constant Load ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Average Size ◽  
Memory Characteristics

Microstructures and deformation behaviour of Ti-45Ni-5Cu and Ti-46Ni-5Cu alloy ribbons prepared by melt spinning were investigated by transmission electron microscopy, thermal cycling tests under constant load and tensile tests. Spherical Ti2Ni particles coherent with the B2 parent phase were observed in the alloy ribbons when the melt spinning temperature was higher than 1773 K. Average size of Ti2Ni particles in the ribbons obtained at 1873 K was 8 nm, which was smaller than that (10 nm) in the ribbons obtained at 1773 K. Volume fraction of Ti2Ni phase in the ribbons obtained at 1873 K was 40%, which was larger than that (20%) in the ribbons obtained at 1773 K. The stress required at temperatures of Af + 10 K for the stress-induced martensitic transformation increased from 93 MPa to 229 MPa and apparent elastic modulus of the B2 parent phase increased from 56 GPa to 250 GPa with increasing the melt spinning temperature from 1673 K to 1873 K in Ti-45Ni-5Cu alloy ribbons. The critical stress for slip deformation of the ribbons increased by coherent Ti2Ni particles, and thus residual elongation did not occur even at 160 MPa, while considerable plastic deformation occurred at 60 MPa in the ribbons without Ti2Ni particles. Almost perfect superelastic recovery was found in the ribbons with coherent Ti2Ni particles, while only partial superelastic recovery was observed in the ribbons without coherent Ti2Ni particles.

Interface Engineering of CNT/Polymer Nanocomposites With Tunable Damping Properties

2018 ◽  
Author(s):  
Michela Talò ◽  
Giulia Lanzara ◽  
Maryam Karimzadeh ◽  
Walter Lacarbonara
Keyword(s):  
Load Transfer ◽  
Mechanical Response ◽  
Material Design ◽  
Tensile Tests ◽  
Nanocomposite Films ◽  
Damping Capacity ◽  
Interfacial Region ◽  
Material Damping ◽  
Stick Slip ◽  
Multi Walled Carbon Nanotubes

In this work, the arising of stick-slip dissipation as well as the global mechanical response of carbon nanotube (CNT) nanocomposite films are tailored by exploiting a three-phase nanocomposite. The three phases are represented by the CNTs, a polymer coating localized on the CNTs surface and a hosting matrix. In particular, a polystyrene (PS) layer coats multi-walled carbon nanotubes (MWNTs) that are randomly dispersed in a polyimide (PI) matrix. The coating phase is strongly bonded to the CNTs outer sidewalls ensuring the effectiveness of the load transfer mechanism and reducing the material damping capacity. The coating phase can be thermally-activated to modify, and in particular, decrease the CNT-matrix interfacial shear strength (ISS) thus facilitating the stick-slip onset in the nanocomposite. The ISS decrease finds its roots in a partial degradation of the coating phase and, in particular, in the formation of voids. By weakening the CNT/polymer interfacial region, a significant enhancement in the material damping capacity is observed. An extensive experimental campaign consisting of monotonic and cyclic tensile tests proved the effectiveness of this novel multi-phase material design.

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