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

e-Polymers ◽  
2004 ◽  
Vol 4 (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.

Thermomechanical Characterization of Bismuth Telluride Based Thermoelectric Materials

2001 ◽  
Vol 691 ◽  
Author(s):  
Witold Brostow ◽  
Kevin P. Menard ◽  
John B. White
Keyword(s):  
Bismuth Telluride ◽  
Van Der Waals ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Direction Parallel ◽  
Crystalline Polymers ◽  
Structural Metals ◽  
P Type

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.

scholarly journals Assessment of Thermal Transitions by Dynamic Mechanical Analysis (DMA) Using a Novel Disposable Powder Holder

Pharmaceutics ◽  
2010 ◽  
Vol 2 (2) ◽  
pp. 78-90 ◽  
Author(s):  
Mohamad G. Abiad ◽  
Osvaldo H. Campanella ◽  
M. Teresa Carvajal
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Mechanical Analysis ◽  
Thermal Transitions ◽  
Dynamic Mechanical

scholarly journals Dynamic Mechanical Analysis as a Complementary Technique for Stickiness Determination in Model Whey Protein Powders

Foods ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1295
Author(s):  
Laura O’Donoghue ◽  
Md. Haque ◽  
Sean Hogan ◽  
Fathima Laffir ◽  
James O’Mahony ◽  
...  
Keyword(s):  
Glass Transition ◽  
Dynamic Mechanical Analysis ◽  
Whey Protein ◽  
Loss Modulus ◽  
Mechanical Analysis ◽  
Whey Protein Concentrate ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Storage And Loss Moduli ◽  
Lower Protein

The α-relaxation temperatures (Tα), derived from the storage and loss moduli using dynamic mechanical analysis (DMA), were compared to methods for stickiness and glass transition determination for a selection of model whey protein concentrate (WPC) powders with varying protein contents. Glass transition temperatures (Tg) were determined using differential scanning calorimetry (DSC), and stickiness behavior was characterized using a fluidization technique. For the lower protein powders (WPC 20 and 35), the mechanical Tα determined from the storage modulus of the DMA (Tα onset) were in good agreement with the fluidization results, whereas for higher protein powders (WPC 50 and 65), the fluidization results compared better to the loss modulus results of the DMA (Tα peak). This study demonstrates that DMA has the potential to be a useful technique to complement stickiness characterization of dairy powders by providing an increased understanding of the mechanisms of stickiness.

Dynamic Mechanical and Crystallization Properties of PTT/EPDM-g-MA/OMMT Blends

2012 ◽  
Vol 466-467 ◽  
pp. 23-26
Author(s):  
Kun Yan Wang ◽  
Ying Ye ◽  
Xiao Qing Zhu ◽  
Feng Cao
Keyword(s):  
Differential Scanning Calorimetry ◽  
Melting Point ◽  
Maleic Anhydride ◽  
Dynamic Mechanical Analysis ◽  
Mechanical Analysis ◽  
Scanning Calorimetry ◽  
Ethylene Propylene ◽  
Dynamic Mechanical ◽  
Crystallization Properties ◽  
Trimethylene Terephthalate

The blends of poly(trimethylene terephthalate) (PTT) with ethylene-propylene-diene copolymer grafted with maleic anhydride (EPDM-g-MA) and organoclay(OMMT) were prepared by melt blending.The composites were characterized by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The results suggest that the PTT is immiscible with EPDM-g-MA when OMMT was added to the blends. Strorage modulus of the PTT/EPDM-g-MA/OMMT are higher than those of pure PTT. The melting point of pure PTT and blends was almost constant. The crystallinity of the blends with OMMT were higher than that of pure PTT.

Effects of Phenolic Oligomer on the Dynamic Mechanical Properties of Nitrile Butadiene Rubber

2011 ◽  
Vol 335-336 ◽  
pp. 120-123 ◽  
Author(s):  
Chang Su ◽  
Pan He ◽  
Li Huan Xu ◽  
Cheng Zhang
Keyword(s):  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Peak Position ◽  
Butadiene Rubber ◽  
Reaction Products ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Nitrile Butadiene Rubber ◽  
Tan Δ ◽  
Damping Peak

In this article, the damping mechanism of organic hybrids consisting of Nitrile Butadiene Rubber (NBR) and phenolic oligomer 4-methyl-pheno reaction products of both dicyclopentadiene and isobutylene (MPDI) were investigated by dynamic mechanical analysis (DMA). It was shown that NBR/MPDI blends exhibit only one damping peak, which shifted to higher temperature with the increase of MPDI content, and the maximum of tan δ peak decreased slightly when the ratio of NBR/MPDI was no more than 100/20, and then increased when the ratio rised from 100/20 to 100/80. Fourier transform infrared spectrum (FT-IR) showed that the hydrogen bond were formed between -OH of MPDI and a-H of NBR. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) measurements indicated that MPDI exhibit amorphous features, which was compatible with the blends. These may imply that much more stable damping material with both higher tan δ peak and controllable damping peak position can be achieved.

scholarly journals Pharmaceutical Amorphous Organic Materials Characterization by Using the Differential Scanning Calorimetry and Dynamic Mechanical Analysis

2011 ◽  
Vol 6 (2) ◽  
pp. 91-95
Author(s):  
Ion Dranca ◽  
Igor Povar ◽  
Tudor Lupascu
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Dynamic Mechanical Analysis ◽  
Mechanical Analysis ◽  
Relaxation Processes ◽  
Scanning Calorimetry ◽  
Dynamic Mechanical ◽  
Β Relaxation

This research has been carried out in order to demonstrate the use of differential scanning calorimetry (DSC) in detecting and measuring α- and β-relaxation processes in amorphous pharmaceutical systems. DSC has been employed to study amorphous samples of poly (vinylpyrrolidone) (PVP), indomethacin (InM), and ursodeoxycholic acid (UDA) that are annealed at temperature (Ta) around 0.8 of their glass transition temperature (Tg). Dynamic mechanical analysis (DMA) is used to measure β- relaxation in PVP. Yet, the DSC has been used to study the glassy indomethacin aged at 0 and -10 oC for periods of time up to 109 and 210 days respectively. The results demonstrate the emergence of a small melting peak of the α-polymorph after aging for 69 days at 0°C and for 147 days at -10°C (i.e., ~55°C below the glass transition temperature) that provides evidence of nucleation occurring in the temperature region of the β-relaxation.

Dynamic Mechanical Analysis of Synthetic epoxy (E) and Bio-epoxy Polymer Foam Integrated with Wood Filler Under 8000 hours Exposure to UV Irradiation

2020 ◽  
Vol 01 (01) ◽  
Author(s):  
A. Alzomor ◽  
◽  
A. Z. M. Rus ◽  
H. A. Wahab ◽  
N. S. M. Salim ◽  
...  
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Uv Irradiation ◽  
Epoxy Polymer ◽  
Mechanical Analysis ◽  
Filler Material ◽  
Polymer Foam ◽  
Dynamic Mechanical ◽  
Pu Foam ◽  
Powder Filler ◽  
Tan Δ

The most common sustainable polymer for polyurethane (PU) materials is the production of polyurethane (PU) materials using renewable resources, which will reduce thedependency on petroleum-based products for consumption.This research presents findings from an experimental research on dynamic mechanical and viscoelastic properties such as storage module (E'), loss module(E") and damping coefficient(tan δ)of synthetic epoxy (E) and bio-epoxy (B) polymer foam with different loading ratios of 0%, 5%, 10%, 15% and 20% flakes and powder filler.The samples were then exposed to 8000 hours of UV irradiation. The samples were subjected to dynamic mechanical analysis (DMA) over a temperature range of 25-180 ° C for (E) and (B) polymer foam at a frequency of 1 Hz.The results showed that the 20 %synthetic epoxy with flakes filler material, namely as E20L sample with the highest filler ratio, gives the maximum storage module and loss module values (0.3125 MPa and0.0625 MPa respectively), among other filler ratios due to bonding between foam and filler resulting in increased viscosity of the synthetic-epoxy PU foam. The bio-epoxy PU foam with a 5% powder filler material (B5P), has the highest storage value (3,956 MPa) and loss module (17,213 MPa), showing that bio-epoxy PU foams can dissipate energy faster than synthetic-epoxy polymer foams.Thermogravimetric analysis (TGA) showed that the synthetic epoxy (E) polymer foam had a higher Tg value and the highest value was reported by E5L (1.2) compared to bio-epoxy foams with far less repeatable results due to the less homogeneous polyol structure.

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