Electric and thermoelectric properties of cement composites with expanded graphite

Pichór, Waldemar; Frąc, Maksymilian

doi:10.1533/9780857099891.43

Cited by 12 publications

(2 citation statements)

References 5 publications

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“…The inflection point of the sigmoid fits, at X(GR) = 0.304 for the powders and X(GR) = 0.307 for the pastes, gives a further detail on the change of the Seebeck coefficient in the mixtures, which is required later. Otherwise, the thermopowers of the pure powders are consistent with the reported values, which span between 200 mV K À1 and 1700 mV K À1 for copper(I) oxide, 5,38 and between 2 mV K À1 and 60 mV K À1 (positive or negative sign) for graphite, [39][40][41][42][43][44][45][46] depending on factors such as homogeneity, crystallinity and sample preparation. The opposite behavior can be observed in the case of the electrical conductivity (in Fig.…”

Section: Thermoelectric Propertiessupporting

confidence: 88%

Adjusting the thermoelectric properties of copper(i) oxide–graphite–polymer pastes and the applications of such flexible composites

Andrei

Bethke

Rademann

2016

Phys. Chem. Chem. Phys.

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We present a facile alternative to other well known strategies for synthesizing flexible thermoelectric materials. Instead of printing thin active layers on flexible substrates or doping conductive polymers, we produce thermoelectric pastes, using a mixture of graphite, copper(I) oxide and polychlorotrifluoroethene. The Seebeck coefficient of the investigated pastes varies between 10 and 600 μV K(-1), while the electrical conductivity spans over an even wider range of 10(-4) to 10(2) S m(-1). Here, the influence of phenomena such as percolation on the electrical transport is revealed. The resulting power factor reaches 5.69 × 10(-4) ± 0.70 × 10(-4) μW m(-1) K(-2) for the graphite-polymer paste, with an unexpected minimum at a graphite molar fraction of approximately 0.4. The values are comparable to those of the powder mixtures, which are slightly higher, but less precisely tunable. Such compounds are further evaluated for practical applications. The graphite-polymer paste is used to exemplify, how a flexible thermoelectric sensor can be easily manufactured, step by step. Our results represent a proof of principle, that thermoelectric pastes are viable alternatives to current solutions. A further expansion of the scope for the composites can be achieved by using high performance thermoelectric materials and conductive polymers.

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Section: Thermoelectric Propertiessupporting

confidence: 88%

Adjusting the thermoelectric properties of copper(i) oxide–graphite–polymer pastes and the applications of such flexible composites

Andrei

Bethke

Rademann

2016

Phys. Chem. Chem. Phys.

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“…In this study, expanded graphite, a very promising material that may eliminate most of the disadvantages of existing conductive additives, was used in this role. Previous papers [30][31][32][33][34][35] showed that the addition of 2-3 wt% of expanded graphite to cement composites (compared to the addition of 30-40 wt% graphite powder) resulted in the formation of a conductive network throughout the cement matrix. The resistivity of composites with a content of 3 wt% of expanded graphite is about 10 4 Á cm, 32 whereas Chen and Chung 30 obtained the same value with a content of 2.2 wt%.…”

Section: Introductionmentioning

confidence: 99%

Cement composites with expanded graphite as resistance heating elements

Frąc

Pichór

Szołdra

2020

Journal of Composite Materials

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The following paper presents the results of research on cement composites with expanded graphite as resistance heating elements. Samples of cement mortar were prepared with expanded graphite obtained from intercalated graphite by means of rapid heating at 1000℃. Monotonic and cyclic self-heating tests of cement composites with differing contents of expanded graphite were conducted. In the monotonic self-heating test, the electrical current and the surface temperature of the cement composites with expanded graphite were measured at temperatures 23℃ and –10℃ in order to evaluate their capacity to generate heat. The maximum temperature of composites, the time required to raise the temperature by 10℃, and the power density were determined. Five cycles were applied in the cyclic self-heating test to investigate heat-dependent mechanical properties. The results of the research revealed that cement composites with expanded graphite exhibited promising properties for application as resistance heating elements.

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