Thermomechanical Characterization of Bismuth Telluride Based Thermoelectric Materials

ABSTRACTThe thermoelectric properties of bismuth telluride based thermoelectric (TE) materials are well-characterized, but comparatively little has been published on the mechanical and thermomechanical properties of these materials. In this paper, we present the initial dynamic mechanical analysis (DMA) data for n-type and p-type bismuth telluride based TE materials. The materials' tan δ values, indicative of viscoelastic energy dissipation modes, approach that of glassy or crystalline polymers and are greater than ten times the tan delta of structural metals. TE samples measured perpendicular to the van der Waals planes have higher tan δ values. Thermal scans in the DMA compressive mode showed changes in mechanical properties versus temperature with clear hysteresis effects. These changes were correlated to differential scanning calorimetry (DSC) thermal transitions. The expected anisotropy was shown in flexural 3-point bending results for one n-type material that showed a storage modulus of 0.10 to 0.45 GPa in the direction parallel to the van der Waals planes and 0.07 to 0.2 GPa in the perpendicular direction.

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Application of dynamic mechanical analysis techniques to bismuth telluride based thermoelectric materials

e-Polymers ◽

10.1515/epoly.2004.4.1.500 ◽

2004 ◽

Vol 4 (1) ◽

Cited By ~ 1

Author(s):

Witold Brostow ◽

Kevin P. Menard ◽

John B. White

Keyword(s):

Dynamic Mechanical Analysis ◽

Bismuth Telluride ◽

Polymeric Materials ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Thermal Transitions ◽

Scanning Calorimetry ◽

Dynamic Mechanical ◽

Tan Δ ◽

Te Material

Abstract Dynamic mechanical analysis (DMA) techniques are commonly applied to characterize polymer-based materials - but little if at all to characterize semiconductor thermoelectric (TE) materials. TE materials may be coupled with polymeric materials in advanced thermoelectric devices, and the knowledge of TE material properties will be useful in the choice of materials for future applications. We have obtained DMA results for both n-type and p-type bismuth telluride based TE materials. We find that tan δ values, indicative of viscoelastic energy dissipation modes, approach the values for glassy or semi-crystalline polymers, and are larger by more than a whole order of magnitude than the tan δ of structural metals. DMA thermal scans show clear hysteresis-type effects and a correlation with differential scanning calorimetry thermal transitions. DMA properties as a function of frequency are briefly discussed. Our results show that DMA techniques are useful in the evaluation of thermophysical and thermomechanical properties of these TE materials and of assembled coolers. The viscoelastic effects we report may provide a damping mechanism for severe stresses inherent to service conditions of the TE coolers.

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Influence of 1D and 2D Carbon Fillers and Their Functionalisation on Crystallisation and Thermomechanical Properties of Injection Moulded Nylon 6,6 Nanocomposites

Journal of Nanomaterials ◽

10.1155/2014/670261 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 2

Author(s):

Fabiola Navarro-Pardo ◽

Ana L. Martínez-Hernández ◽

Victor M. Castaño ◽

José L. Rivera-Armenta ◽

Francisco J. Medellín-Rodríguez ◽

...

Keyword(s):

Mechanical Analysis ◽

Thermomechanical Properties ◽

Reduced Form ◽

Scanning Calorimetry ◽

Graphene Nanocomposites ◽

Moulding Process ◽

Nylon 6,6 ◽

Injection Moulding Process ◽

The One ◽

Carbon Fillers

Carbon nanotubes (CNTs) and graphene were used as reinforcing fillers in nylon 6,6 in order to obtain nanocomposites by using an injection moulding process. The two differently structured nanofillers were used in their pristine or reduced form, after oxidation treatment and after amino functionalisation. Three low nanofiller contents were employed. Crystallisation behaviour and perfection of nylon 6,6 crystals were determined by differential scanning calorimetry and wide angle X-ray diffraction, respectively. Crystallinity was slightly enhanced in most samples as the content of the nanofillers was increased. The dimensionality of the materials was found to provide different interfaces and therefore different features in the nylon 6,6 crystal growth resulting in improved crystal perfection. Dynamical, mechanical analysis showed the maximum increases provided by the two nanostructures correspond to the addition of 0.1 wt.% amino functionalised CNTs, enhancing in 30% the storage modulus and the incorporation of 0.5 wt.% of graphene oxide caused an increase of 44% in this property. The latter also provided better thermal stability when compared to pure nylon 6,6 under inert conditions. The superior properties of graphene nanocomposites were attributed to the larger surface area of the two-dimensional graphene compared to the one-dimensional CNTs.

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The Effect of POSS Type on the Shape Memory Properties of Epoxy-Based Nanocomposites

Molecules ◽

10.3390/molecules25184203 ◽

2020 ◽

Vol 25 (18) ◽

pp. 4203

Author(s):

Avraham I. Bram ◽

Irina Gouzman ◽

Asaf Bolker ◽

Noam Eliaz ◽

Ronen Verker

Keyword(s):

Transition Temperature ◽

Shape Memory ◽

Crosslinking Density ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Space Environment ◽

Scanning Calorimetry ◽

Space Applications ◽

Curing Conditions ◽

Oligomeric Silsesquioxane

Thermally activated shape memory polymers (SMPs) can memorize a temporary shape at low temperature and return to their permanent shape at higher temperature. These materials can be used for light and compact space deployment mechanisms. The control of transition temperature and thermomechanical properties of epoxy-based SMPs can be done using functionalized polyhedral oligomeric silsesquioxane (POSS) additives, which are also known to improve the durability to atomic oxygen in the space environment. In this study, the influence of varying amounts of two types of POSS added to epoxy-based SMPs on the shape memory effect (SME) were studied. The first type contained amine groups, whereas the second type contained epoxide groups. The curing conditions were defined using differential scanning calorimetry and glass transition temperature (Tg) measurements. Thermomechanical and SME properties were characterized using dynamic mechanical analysis. It was found that SMPs containing amine-based POSS show higher Tg, better shape fixity and faster recovery speed, while SMPs containing epoxide-based POSS have higher crosslinking density and show superior thermomechanical properties above Tg. This work demonstrates how the Tg and SME of SMPs can be controlled by the type and amount of POSS in an epoxy-based SMP nanocomposite for future space applications.

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Thermal and Thermomechanical Properties of Poly(butylene succinate) Nanocomposites

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.18231 ◽

2008 ◽

Vol 8 (4) ◽

pp. 1679-1689 ◽

Cited By ~ 1

Author(s):

Mamookho E. Makhatha ◽

Suprakas Sinha Ray ◽

Joseph Hato ◽

Adriaan S. Luyt

Keyword(s):

Thermal Stability ◽

Tensile Modulus ◽

Melting Behavior ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Scanning Calorimetry ◽

Melt Mixing ◽

Butylene Succinate ◽

Modulated Differential Scanning Calorimetry ◽

Thermal Stability Of

This article describes the thermal and thermomechanical properties of poly(butylene succinate) (PBS) and its nanocomposites. PBS nanocomposites with three different weight ratios of organically modified synthetic fluorine mica (OMSFM) have been prepared by melt-mixing in a batch mixer at 140 °C. The structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD) analyses and transmission electron microscopy (TEM) observations that reveal the homogeneous dispersion of the intercalated silicate layers into the PBS matrix. The thermal properties of pure PBS and the nanocomposite samples were studied by both conventional and temperature modulated differential scanning calorimetry (DSC) analyses, which show multiple melting behavior of the PBS matrix. The investigation of the thermomechanical properties was performed by dynamic mechanical analysis. Results reveal significant improvement in the storage modulus of neat PBS upon addition of OMSFM. The tensile modulus of neat PBS is also increased substantially with the addition of OMSFM, however, the strength at yield and elongation at break of neat PBS systematically decreases with the loading of OMSFM. The thermal stability of the nanocomposites compared to that of the pure polymer sample was examined under both pyrolytic and thermooxidative environments. It is shown that the thermal stability of PBS is increased moderately in the presence of 3 wt% of OMSFM, but there is no significant effect on further silicate loading in the oxidative environment. In the nitrogen environment, however, the thermal stability systematically decreases with increasing clay loading.

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The Influence of the Furan and Maleimide Stoichiometry on the Thermoreversible Diels–Alder Network Polymerization

Polymers ◽

10.3390/polym13152522 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2522

Author(s):

Ali Safaei ◽

Seppe Terryn ◽

Bram Vanderborght ◽

Guy Van Assche ◽

Joost Brancart

Keyword(s):

Transition Temperature ◽

Functional Groups ◽

Polymer Networks ◽

Viscoelastic Behavior ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Diels Alder ◽

Stoichiometric Ratio ◽

Self Healing ◽

Scanning Calorimetry

In recent work, the thermoreversible Diels–Alder reaction between furan and maleimide functional groups has been studied extensively in the context of self-healing elastomers and thermosets. To elaborate the influence of the stoichiometric ratio between the maleimide and furan reactive groups on the thermomechanical properties and viscoelastic behavior of formed reversible covalent polymer networks, a series of Diels–Alder-based networks with different stoichiometric ratios was synthesized. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and dynamic rheology measurements were performed on the reversible polymer networks, to relate the reversible network structure to the material properties and reactivity. Such knowledge allows the design and optimization of the thermomechanical behavior of the reversible networks for intended applications. Lowering the maleimide-to-furan ratio creates a deficit of maleimide functional groups, resulting in a decrease in the crosslink density of the system, and a consequent decrease in the glass transition temperature, Young’s modulus, and gel transition temperature. The excess of unreacted furan in the system results in faster reaction and healing kinetics and a shift of the reaction equilibrium.

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Calorimetric and Thermomechanical Properties of Titanium-Based Orthodontic Wires: DSC–DMA Relationship to Predict the Elastic Modulus

Journal of Biomaterials Applications ◽

10.1177/0885328210388678 ◽

2011 ◽

Vol 26 (7) ◽

pp. 829-844 ◽

Cited By ~ 14

Author(s):

Giuliana Laino ◽

Roberto De Santis ◽

Antonio Gloria ◽

Teresa Russo ◽

David Suárez Quintanilla ◽

...

Keyword(s):

Elastic Modulus ◽

Young’S Modulus ◽

Mechanical Performance ◽

Young's Modulus ◽

Experimental Tests ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Scanning Calorimetry ◽

Orthodontic Wires ◽

Gum Metal

Orthodontic treatment is strongly dependent on the loads developed by metal wires, and the choice of an orthodontic archwire should be based on its mechanical performance. The desire of both orthodontists and engineers would be to predict the mechanical behavior of archwires. To this aim, Gum Metal (Toyota Central R&L Labs., Inc.), TMA (ORMCO), 35°C Copper NiTi (SDS ORMCO), Thermalloy Plus (Rocky Mountain), Nitinol SE (3M Unitek), and NiTi (SDS ORMCO) were tested according to dynamic mechanical analysis and differential scanning calorimetry. A model was also developed to predict the elastic modulus of superelastic wires. Results from experimental tests have highlighted that superelastic wires are very sensitive to temperature variations occurring in the oral environment, while the proposed model seems to be reliable to predict the Young’s modulus allowing to correlate calorimetric and mechanical data. Furthermore, Gum Metal wire behaves as an elastic material with a very low Young’s modulus, and it can be particularly useful for the initial stage of orthodontic treatments.

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Poly(etheretherketone)/Poly(ethersulfone) Blends with Phenolphthalein: Miscibility, Thermomechanical Properties, Crystallization and Morphology

Polymers ◽

10.3390/polym13091466 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1466

Author(s):

Adrian Korycki ◽

Christian Garnier ◽

Amandine Abadie ◽

Valerie Nassiet ◽

Charles Tarek Sultan ◽

...

Keyword(s):

Differential Scanning Calorimetry ◽

Interfacial Adhesion ◽

Morphological Analysis ◽

Condensation Reaction ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Glass Transitions ◽

Scanning Calorimetry ◽

Melt Mixing ◽

Spherical Domains

Polyetheretherketone (PEEK)/polyethersulfone (PES) blends are initially not miscible, except when the blends are prepared by solvent mixing. We propose a route to elaborate PEEK/PES blends with partial miscibility by melt mixing at 375 °C with phenolphthalein. The miscibility of blends has been examined using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMTA). When adding phenolphthalein to PEEK/PES blends, the glass transitions are shifted inward as an indication of miscibility. We suggest that phenolphthalein acts as a compatibilizer by creating cardo side groups on PEEK and PES chains by nucleophilic substitution in the melted state, although this condensation reaction was reported only in the solvent until now. In addition, phenolphthalein acts as a plasticizer for PES by decreasing its glass transition. As a consequence, the PEEK phase is softened which favors the crystallization as the increase of crystalline rate. Due to aromatic moieties in phenolphthalein, the storage modulus of blends in the glassy region is kept identical to pure PEEK. The morphological analysis by SEM pictures displays nano- to microsized PES spherical domains in the PEEK matrix with improved PEEK/PES interfacial adhesion.

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Photocuring of Epoxidized Cardanol for Biobased Composites with Microfibrillated Cellulose

Molecules ◽

10.3390/molecules24213858 ◽

2019 ◽

Vol 24 (21) ◽

pp. 3858 ◽

Cited By ~ 5

Author(s):

Sara Dalle Vacche ◽

Alessandra Vitale ◽

Roberta Bongiovanni

Keyword(s):

Uv Light ◽

Side Reaction ◽

Reaction Rates ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Microfibrillated Cellulose ◽

Green Technology ◽

Raw Material ◽

Scanning Calorimetry ◽

Renewable Raw Material

Cardanol is a natural alkylphenolic compound derived from Cashew NutShell Liquid (CNSL), a non-food annually renewable raw material extracted from cashew nutshells. In the quest for sustainable materials, the curing of biobased monomers and prepolymers with environmentally friendly processes attracts increasing interest. Photopolymerization is considered to be a green technology owing to low energy requirements, room temperature operation with high reaction rates, and absence of solvents. In this work, we study the photocuring of a commercially available epoxidized cardanol, and explore its use in combination with microfibrillated cellulose (MFC) for the fabrication of fully biobased composites. Wet MFC mats were prepared by filtration, and then impregnated with the resin. The impregnated mats were then irradiated with ultraviolet (UV) light. Fourier Transform InfraRed (FT-IR) spectroscopy was used to investigate the photocuring of the epoxidized cardanol, and of the composites. The thermomechanical properties of the composites were assessed by thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. We confirmed that fully cured composites could be obtained, although a high photoinitiator concentration was needed, possibly due to a side reaction of the photoinitiator with MFC.

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Effect of diacylhydrazine as chain extender on microphase separation and performance of energetic polyurethane elastomer

e-Polymers ◽

10.1515/epoly-2020-0052 ◽

2020 ◽

Vol 20 (1) ◽

pp. 469-481

Author(s):

Yang Gao ◽

Jie Lv ◽

Licheng Liu ◽

Yingfeng Yu

Keyword(s):

Hydrogen Bonding ◽

Hard Segment ◽

Microphase Separation ◽

Low Cost ◽

Ethylene Carbonate ◽

Mechanical Analysis ◽

Chain Extender ◽

Thermal Transitions ◽

Scanning Calorimetry ◽

Hard Segment Content

AbstractIt is low cost and feasible to improve the mechanical properties of polyurethane by using the chain extender with hydrogen bonding function to improve the degree of microphase separation. In this article, hydrazine hydrate was used to react with ethylene carbonate and propylene carbonate, respectively, to synthesize diacylhydrazines as the polyurethane chain extender with amide bonds, which were characterized by 1H nuclear magnetic resonance. Polyurethane with different contents of hard segment were prepared from poly-3,3-bis(azidomethyl)oxetane-tetrahydrofuran as the polyol and 4,4′-diphenylmethane diisocyanate as the isocyanate components. Fourier transform infrared spectroscopy showed that with the increase of the hard segment content, the proportion of hydrogen-bonded ordered carbonyl group increased to 94%, proving that diacylhydrazines could improve the degree of ordered hydrogen bonding, which led to clear microphase separation observed by field emission scanning electron microscopy and higher storage modulus of the polyurethane. Differential scanning calorimetry and dynamic mechanical analysis showed that polyurethane with higher hard segment content is likely to exhibit multiple thermal transitions caused by microphase separation. When the hard segment content was 40%, compared with polyurethane with 1,4-butanediol as the chain extender, the tensile strengths of polyurethanes with diacylhydrazines also improved by 30% and 76%, respectively.

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Self-Healable and Recyclable Biomass-Derived Polyurethane Networks through Carbon Dioxide Immobilization

Polymers ◽

10.3390/polym13244381 ◽

2021 ◽

Vol 13 (24) ◽

pp. 4381

Author(s):

Seohyun Baek ◽

Juhyen Lee ◽

Hyunwoo Kim ◽

Inhwan Cha ◽

Changsik Song

Keyword(s):

Carbon Dioxide ◽

Mechanical Analysis ◽

Thermomechanical Properties ◽

Polymer Materials ◽

Self Healing ◽

Scanning Calorimetry ◽

Covalent Bonds ◽

Thermal Mechanical Analysis ◽

Carbon Dioxide Co2 ◽

Combined Strategy

Due to growing environmental issues, research on carbon dioxide (CO2) use is widely conducted and efforts are being made to produce useful materials from biomass-derived resources. However, polymer materials developed by a combined strategy (i.e., both CO2-immobilized and biomass-derived) are rare. In this study, we synthesized biomass-derived poly(carbonate-co-urethane) (PCU) networks using CO2-immobilized furan carbonate diols (FCDs) via an ecofriendly method. The synthesis of FCDs was performed by directly introducing CO2 into a biomass-derived 2,5-bis(hydroxymethyl)furan. Using mechanochemical synthesis (ball-milling), the PCU networks were effortlessly prepared from FCDs, erythritol, and diisocyanate, which were then hot-pressed into films. The thermal and thermomechanical properties of the PCU networks were thoroughly characterized by thermogravimetric analysis, differential scanning calorimetry, dynamic (thermal) mechanical analysis, and using a rheometer. The self-healing and recyclable properties of the PCU films were successfully demonstrated using dynamic covalent bonds. Interestingly, transcarbamoylation (urethane exchange) occurred preferentially as opposed to transcarbonation (carbonate exchange). We believe our approach presents an efficient means for producing sustainable polyurethane copolymers using biomass-derived and CO2-immobilized diols.

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