Thermal conductivity of a polymer filled with particles in the wide range from low to super-high volume content

1990 ◽  
Vol 40 (56) ◽  
pp. 929-941 ◽  
Author(s):  
Y. Agari ◽  
A. Ueda ◽  
M. Tanaka ◽  
S. Nagai
Keyword(s):  
Thermal Conductivity ◽  
Volume Content ◽  
High Volume ◽  
Wide Range

scholarly journals THERMAL CONDUCTIVITY OF COMPOSITIONS BASED ON A SILOXANE BINDER WITH A HIGH FILLER CONTENT OF ALUMINUM HYDROXIDE POWDER

2018 ◽  
pp. 39-43
Author(s):  
V. Sh. Sulaberidze ◽  
V. D. Mushenko ◽  
V. A. Mikheev
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Aluminum Hydroxide ◽  
Volume Content ◽  
Room Temperature ◽  
Filler Content ◽  
Heat Conducting ◽  
Temperature Range ◽  
Wide Range ◽  
Volumetric Content

The use of aluminum hydroxide as a filler in composite materials makes them non-flammable. When the thermal conductivity of such compositions is above 1 W/(m-K), they can be used as heat-conducting insulating and non-flammable coatings in power electronics. Thermal conductivity of compositions based on dimethylsiloxane with a filler made from aluminum hydroxide powders of various dissipation is studied in the temperature range from 25 °C to 200 °C, depending on the volume content of the filler. With a volumetric content of filler up to 60%, no significant differences in the values of the thermal conductivity of samples with powders of the investigated fractional groups were detected. With volumetric content of the filler more than 40%, the thermal conductivity of the composition at room temperature exceeded 1 W/(m-K). It is shown that the Burger formula modified by the authors turned out to be sufficiently universal for the calculated estimates of the thermal conductivity of materials with different fillers in a wide range of their volume contents.

scholarly journals A Multiscale Investigation on the Thermal Transport in Polydimethylsiloxane Nanocomposites: Graphene vs. Borophene

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1252
Author(s):  
Alessandro Di Pierro ◽  
Bohayra Mortazavi ◽  
Hamidreza Noori ◽  
Timon Rabczuk ◽  
Alberto Fina
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Effective Thermal Conductivity ◽  
Polymer Nanocomposites ◽  
Volume Content ◽  
Thermal Conductance ◽  
Single Layer ◽  
Md Simulations ◽  
Aspect Ratios ◽  
Wide Range

Graphene and borophene are highly attractive two-dimensional materials with outstanding physical properties. In this study we employed combined atomistic continuum multi-scale modeling to explore the effective thermal conductivity of polymer nanocomposites made of polydimethylsiloxane (PDMS) polymer as the matrix and graphene and borophene as nanofillers. PDMS is a versatile polymer due to its chemical inertia, flexibility and a wide range of properties that can be tuned during synthesis. We first conducted classical Molecular Dynamics (MD) simulations to calculate the thermal conductance at the interfaces between graphene and PDMS and between borophene and PDMS. Acquired results confirm that the interfacial thermal conductance between nanosheets and polymer increases from the single-layer to multilayered nanosheets and finally converges, in the case of graphene, to about 30 MWm−2 K−1 and, for borophene, up to 33 MWm−2 K−1. The data provided by the atomistic simulations were then used in the Finite Element Method (FEM) simulations to evaluate the effective thermal conductivity of polymer nanocomposites at the continuum level. We explored the effects of nanofiller type, volume content, geometry aspect ratio and thickness on the nanocomposite effective thermal conductivity. As a very interesting finding, we found that borophene nanosheets, despite having almost two orders of magnitude lower thermal conductivity than graphene, can yield very close enhancement in the effective thermal conductivity in comparison with graphene, particularly for low volume content and small aspect ratios and thicknesses. We conclude that, for the polymer-based nanocomposites, significant improvement in the thermal conductivity can be reached by improving the bonding between the fillers and polymer, or in other words, by enhancing the thermal conductance at the interface. By taking into account the high electrical conductivity of borophene, our results suggest borophene nanosheets as promising nanofillers to simultaneously enhance the polymers’ thermal and electrical conductivity.

scholarly journals A Slot-Die Technique for the Preparation of Continuous, High-Area, Chitosan-Based Thin Films

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1566
Author(s):  
Oliver J. Pemble ◽  
Maria Bardosova ◽  
Ian M. Povey ◽  
Martyn E. Pemble
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
High Volume ◽  
Mechanical Anisotropy ◽  
Diverse Range ◽  
Direction Parallel ◽  
High Area ◽  
Wide Range ◽  
Slot Die ◽  
Potential Applications

Chitosan-based films have a diverse range of potential applications but are currently limited in terms of commercial use due to a lack of methods specifically designed to produce thin films in high volumes. To address this limitation directly, hydrogels prepared from chitosan, chitosan-tetraethoxy silane, also known as tetraethyl orthosilicate (TEOS) and chitosan-glutaraldehyde have been used to prepare continuous thin films using a slot-die technique which is described in detail. By way of preliminary analysis of the resulting films for comparison purposes with films made by other methods, the mechanical strength of the films produced was assessed. It was found that as expected, the hybrid films made with TEOS and glutaraldehyde both show a higher yield strength than the films made with chitosan alone. In all cases, the mechanical properties of the films were found to compare very favorably with similar measurements reported in the literature. In order to assess the possible influence of the direction in which the hydrogel passes through the slot-die on the mechanical properties of the films, testing was performed on plain chitosan samples cut in a direction parallel to the direction of travel and perpendicular to this direction. It was found that there was no evidence of any mechanical anisotropy induced by the slot die process. The examples presented here serve to illustrate how the slot-die approach may be used to create high-volume, high-area chitosan-based films cheaply and rapidly. It is suggested that an approach of the type described here may facilitate the use of chitosan-based films for a wide range of important applications.

Study of Method for Determination of Thermal Conductivity of Automotive Interior Materials

2014 ◽  
Vol 526 ◽  
pp. 46-51
Author(s):  
Li Xiong Zhang ◽  
Rong Gang Gao
Keyword(s):  
Thermal Conductivity ◽  
Conductivity Measurement ◽  
Transient Heat Conduction ◽  
Traditional Theory ◽  
Infinite Plane ◽  
Plane Source ◽  
Transient Plane Source ◽  
Wide Range ◽  
Automotive Interior

Based on the traditional theory of transient plane source for thermal conductivity measurement, this paper designed and developed a new pattern of heating and temperature sensing probe, presented the study of transient heat conduction of half-infinite plane while being heated, established a modified mathematical model of transient plane source method, and achieved the measurement of thermal conductivity of automotive interior material sample by the data processing method of mathematical iteration and liner regression using the modified transient plane source probe. According to the data of experiments, the instrument which this paper designed has a high precision of 5% and a wide range of 0.003-1W/(mK).This paper provides a practicable way for heat capacity determination of automotive interior materials.

Evaporite Palynology: a case study on the Permian (Lopgingian) Zechstein Sea

2021 ◽  
pp. jgs2020-174
Author(s):  
Martha E. Gibson ◽  
David J. Bodman
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Rapid Growth ◽  
Western Europe ◽  
Thermal Maturity ◽  
Near Surface ◽  
Wide Range ◽  
Terrestrial Environments ◽  
Insight Into

Evaporites characterize the Lopingian of Europe but present obstacles for biostratigraphic analysis. Here we present a case study for processing the Lopingian Zechstein Group evaporites of central-western Europe for the recovery of palynomorph assemblages. We demonstrate that full recovery is easily achieved with two main modes of palynomorph preservation observed; palynomorphs are either exceptionally well-preserved and orange-brown in colour, or poorly-preserved, brown-black, opaque and fragmented. The latter are reminiscent of palynomorphs of high thermal maturity. However, we propose that the intact nature of preservation is a result of the rapid growth of near-surface halite crystals, with their darkening a consequence of locally-enhanced heat flux due to the relatively high thermal conductivity of salt. This case study has enabled novel insight into an otherwise undescribed environment, and demonstrates the utility and possibility of extracting palynomorphs from a variety of rock salt types. This method should be applicable to a wide range of ancient evaporite and could also be applied to other Permian evaporite systems, which are used as analogues for extra-terrestrial environments.

An Investigation of Hydrological Effects on the Thermal Performance of Standing Column Well Using the in-situ Thermal Response Test

2019 ◽  
Vol 27 (02) ◽  
pp. 1950015 ◽  
Author(s):  
Keun Sun Chang ◽  
Young Jae Kim ◽  
Min Jun Kim
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Flow Rate ◽  
Large Scale ◽  
Thermal Response ◽  
Thermal Response Test ◽  
Response Test ◽  
Geological Conditions ◽  
Wide Range ◽  
Borehole Thermal Resistance

The standing column well (SCW) for ground source heat pump (GSHP) systems is a highly promising technology with its high heat capacity and efficiency. In this study, a large-scale thermal response tester has been built, which is capable of imposing a wide range of heat on the SCW ground heat exchangers and measuring time responses of their thermal parameters. Two standing column wells in one site but with different well hydrological and geological conditions are tested to study their effects on the thermal performances. Borehole thermal resistance ([Formula: see text]) and the effective thermal conductivity ([Formula: see text]) are derived from data obtained from the thermal response test (TRT) by using a line source method. Results show that the influence of groundwater movement on the thermal conductivity of the SCW is not very significant (3.6% difference between two different geological conditions). This indicates that results of one TRT measurement can be applied to other SCWs in the same site, with which considerable time and cost are saved. The increase of circulation flow rate enhances the ground thermal conductivity moderately (4.5% increase with flow rate increase of 45%), but the borehole thermal resistance is substantially lowered (about 25.9%).

scholarly journals Surgical Management of Neuroendocrine Tumours of the Pancreas

2020 ◽  
Vol 9 (9) ◽  
pp. 2993
Author(s):  
Regis Souche ◽  
Christian Hobeika ◽  
Elisabeth Hain ◽  
Sebastien Gaujoux
Keyword(s):  
Neuroendocrine Tumours ◽  
Islet Cells ◽  
Preoperative Evaluation ◽  
High Volume ◽  
Genetic Syndromes ◽  
Active Peptides ◽  
Wide Range ◽  
Precise Diagnosis ◽  
Short And Long Term ◽  
Open Versus

Neuroendocrine tumours of the pancreas (pNET) are rare, accounting for 1–2% of all pancreatic neoplasms. They develop from pancreatic islet cells and cover a wide range of heterogeneous neoplasms. While most pNETs are sporadic, some are associated with genetic syndromes. Furthermore, some pNETs are ‘functioning’ when there is clinical hypersecretion of metabolically active peptides, whereas others are ‘non-functioning’. pNET can be diagnosed at a localised stage or a more advanced stage, including regional or distant metastasis (in 50% of cases) mainly located in the liver. While surgical resection is the cornerstone of the curative treatment of those patients, pNET management requires a multidisciplinary discussion between the oncologist, radiologist, pathologist, and surgeon. However, the scarcity of pNET patients constrains centralised management in high-volume centres to provide the best patient-tailored approach. Nonetheless, no treatment should be initiated without precise diagnosis and staging. In this review, the steps from the essential comprehensive preoperative evaluation of the best surgical approach (open versus laparoscopic, standard versus sparing parenchymal pancreatectomy, lymphadenectomy) according to pNET staging are analysed. Strategies to enhance the short- and long-term benefit/risk ratio in these particular patients are discussed.

scholarly journals Experimental investigation of rockwool insulation hygrothermal properties related to material structure

2015 ◽  
Vol 19 (3) ◽  
pp. 923-928 ◽  
Author(s):  
Maja Djurovic-Petrovic
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Sorption Properties ◽  
Material Structure ◽  
Insulation Material ◽  
Wide Range ◽  
Two Samples

The hygrothermal properties related to rockwool insulation material structure with different additives are presented using rockwool insulation products obtained from row material of southern Serbia (Vranje region) in the wide range of reference temperatures (10?C to 70?C). The hygrothermal properties of basic sample (without additives) are compared to two samples with different additives for two sets of rockwool insulation samples namely: light-soft-panels (LSP) with density of 50 kg/m3, and middle-weight-panels (MWP) with density of 80 kg/m3. It is shown that there is significant (approximately 10%) improvement of thermal conductivity for additives based on zeolite. Also, correlation of thermal conductivity and sorption properties of selected samples are presented.

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