scholarly journals Achieving High Thermal Conductivity in Epoxy Composites: Effect of Boron Nitride Particle Size and Matrix-Filler Interface

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1156 ◽  
Author(s):  
Sasan Moradi ◽  
Yolanda Calventus ◽  
Frida Román ◽  
John M Hutchinson
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Boron Nitride ◽  
Reaction Kinetics ◽  
Heat Of Reaction ◽  
Scanning Calorimetry ◽  
Base Interaction ◽  
Cure Reaction ◽  
Thermally Conducting ◽  
Nitride Particle

For the thermal management of high watt density circuit layers, it is common to use a filled epoxy system to provide an electrically insulating but thermally conducting bond to a metal substrate. An epoxy-thiol system filled with boron nitride (BN), in the form of 2, 30 and 180 µm platelets, has been investigated with a view to achieving enhanced thermal conductivity. The effect of BN content on the cure reaction kinetics has been studied by differential scanning calorimetry and the thermal conductivity of the cured samples has been measured by the Transient Hot Bridge method. The heat of reaction and the glass transition temperature of the fully cured samples are both independent of the BN content, but the cure reaction kinetics is systematically affected by both BN content and particle size. These results can be correlated with the thermal conductivity of the cured systems, which is found to increase with both BN content and particle size. For a given BN content, the thermal conductivity found here is significantly higher than most others reported in the literature; this effect is attributed to a Lewis acid-base interaction between filler and matrix.

Thermal Conductivity of Elastomer Vulcanizates by Differential Scanning Calorimetry

1982 ◽  
Vol 55 (1) ◽  
pp. 191-207 ◽  
Author(s):  
Anil K. Sircar ◽  
John L. Wells
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Carbon Black ◽  
Polymeric Materials ◽  
High Concentration ◽  
Scanning Calorimetry ◽  
Relationship Of ◽  
Particle Size And Structure ◽  
Thermal Conductivity Λ ◽  
Very High

Abstract A du Pont 990 differential scanning calorimeter was modified to measure thermal conductivity of elastomer vulcanizates. The method is quick and reproducible and is recommended for scouting research of polymeric materials. The thermal conductivity λ values obtained by this method of some known materials compare favorably with those in the literature. Carbon black increases λ values in all elastomers. Particle size and structure of carbon black seem to affect λ values erratically, although the trend is towards higher λ values with larger particle size and higher structure. A linear relationship of λ vs. volume concentration of carbon blacks and other fillers is observed, except at a very high concentration. The extrapolated values of λ for a filler differ in different elastomeric media. Noncompatible elastomer blends increase or decrease λ values according to the nature and proportion of elastomers. The effect of the manner of addition of carbon black does not seem to affect the λ value of compatible blends. Higher temperatures decrease λ values for all the vulcanizates studied.

Study on curing kinetics of a diglycidyl ether of bisphenol A epoxy resin/microencapsulated curing agent system

2012 ◽  
Vol 24 (8) ◽  
pp. 730-737 ◽  
Author(s):  
Wang Fang ◽  
Xiao Jun ◽  
Wang Jing-wen ◽  
Li Shu-qin
Keyword(s):  
Particle Size ◽  
Bisphenol A ◽  
Epoxy Resin ◽  
Diglycidyl Ether ◽  
Wall Material ◽  
Curing Agent ◽  
Resin System ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Epoxy Resin System

A modified imidazole curing agent, EMI-g-BGE, was encapsulated for one-package of diglycidyl ether of bisphenol A (DGEBA) epoxy resin system. Polyetherimide (PEI) was used as the wall material, and the emulsion solvent evaporation method was used to form the microcapsules. The morphology and particle size distribution of microcapsules were evaluated by scanning electron microscopy (SEM), mastersizer analyzer. Microcapsules exhibited spherical shapes and the mean particle size was about 745 nm. The curing kinetic of DGEBA/microcapsules curing agent was studied by nonisothermal differential scanning calorimetry (DSC) technique at different heating rates. Dynamic DSC scans indicated the microcapsule was an effective curing agent of epoxy resin. The apparent activation energy Ea was 88.03 kJ/mol calculated through Kissinger method, more than DGEBA/EMI-g-BGE system. This microcapsule of EMI-g-BGE exhibited a long shelf life, and the curing did not occur in this epoxy-microcapsule resin system for more than 3months at room temperature. The kinetic parameters were determined by Málek method and a two-parameter ( m, n) autocatalytic model (Šesták–Berggren equation) was found to be the most adequate selected kinetic model, which showed the encapsulation of the curing agent EMI-g-BGE did not change the cure reaction mechanism of the epoxy resin system. From the experimental data, the nonisothermal DSC curves show the results being in accordant with those theoretically calculated.

Effects of Styrene Evaporation on the Cure Kinetics Behaviour of a Vinylester Resin System Suitable for Composite Pultrusion

2003 ◽  
Vol 11 (8) ◽  
pp. 623-632 ◽  
Author(s):  
Z I Samaras ◽  
I K Partridge
Keyword(s):  
Cure Kinetics ◽  
Heat Of Reaction ◽  
Initial Sample ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Vinylester Resin ◽  
Diffusion Limitations ◽  
Individual Reaction ◽  
Styrene Content ◽  
The Individual

The paper describes the effects of styrene evaporation on the curing reactions of a vinylester resin, explored by the use of differential scanning calorimetry. The thermosetting system under study is characterized by the presence of three distinct exothermic peaks, attributed to different cure reaction mechanisms. A chemical cure kinetics model is presented, incorporating effects of diffusion limitations on the later stages of the cure. Whilst the nature of the curing mechanism is unaffected by the loss of styrene, the expected reductions in the overall heat of reaction from the individual reaction components are noted and quantified. The glass to rubber transition temperature, Tg, of fully cured resin is shown to decrease from 124°C in the initial sample to 121°C in samples in which over 20% of the initial styrene content had evaporated.

scholarly journals Experimental Investigation of Thermal Conductivity and Specific Heat of the Calcium Phosphate Ore for a Drying Application

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zhor El Hallaoui ◽  
T. Moudakkar ◽  
S. Vaudreuil ◽  
T. Bounahmidi ◽  
S. Abderafi
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Particle Size ◽  
Moisture Content ◽  
Specific Heat ◽  
Regression Models ◽  
Average Error ◽  
Scanning Calorimetry ◽  
Temperature Estimation ◽  
Modulated Differential Scanning Calorimetry

This paper discusses an experimental investigation to determine regression models for thermal properties of phosphate particles and to analyze the performances of the phosphate flash dryer. For this purpose, the specific heat capacity and thermal conductivity of phosphate particles were experimentally determined by the modulated differential scanning calorimetry (MDSC) and the modified transient plane source method (MTPS), respectively. Multiple regression models were developed to correlate the specific heat and thermal conductivity to moisture content, particle size, and temperature. Experimental results showed that the measured thermal conductivity and dry specific heat were found in the range of 0.07–0.61 W/m K and 510–630 J/kg·K, respectively. Furthermore, the specific heat increased almost linearly with temperature but decreased with particle size, while the thermal conductivity increased with moisture content and temperature but decreased with particle size. These correlations were integrated to the phosphate flash dryer mathematical model and used to analyze the thermal behavior of phosphate drying. Simulation results were compared to experimental data obtained on a bench-scale dryer, where the model exhibits an average error of 2% and 4% for moisture content and air temperature estimation, showing good fitting for practical data.

Thermal Conductivity of Fly Ash Cenospheres for Variable Particle Size Ranges

2016 ◽  
Vol 4 (2) ◽  
pp. 19
Author(s):  
MENEZES CRAIG ◽  
RATHOD AJIT P ◽  
WASEWAR KAILAS L. ◽  
◽  
◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Fly Ash ◽  
Fly Ash Cenospheres

Optimasi Proses Pembuatan dan Karakterisasi Fisik Niosom Sinkonin

2019 ◽  
Vol 16 (2) ◽  
pp. 178
Author(s):  
Hariyanti Hariyanti ◽  
Sophi Damayanti ◽  
Sasanti Tarini
Keyword(s):  
Differential Scanning Calorimetry ◽  
Particle Size ◽  
Hair Follicle ◽  
Scanning Calorimetry ◽  
Span 60

Sinkonin praktis tidak larut dalam air, sedikit larut dalam kloroform dan alkohol. Hal ini berdampak pada rendahnya penetrasi transfollicular sinkonin, karena hanya bahan aktif hidrofilik yang mampu melewati hair follicle. Dengan demikian dibutuhkan satu sistem penghantaran yang mampu menurunkan hidrofobisitas sinkonin untuk meningkatkan penetrasi sinkonin ke follicle. Niosom merupakan vesikel ampifilik dengan struktur lapisan rangkap yang terbentuk dari hidrasi kombinasi surfaktan nonionik dan kolesterol yang mampu menurunkan hidrofobisitas sinkonin. Penelitian ini bertujuan untuk menentukan proses pembuatan niosom sinkonin yang optimum. Pembuatan niosom sinkonin diawali dengan menentukan temperatur gelasi (Tg) dari span 60 dengan Differential Scanning Calorimetry (DSC), kemudian dilanjutkan dengan optimasi proses meliputi: optimasi kecepatan rotavapor pembentukan film lapis tipis, temperatur hidrasi, kecepatan rotavapor hidrasi, waktu hidrasi, dan waktu sonikasi. Karakteristik vesikel niosom yang optimal meliputi: ukuran partikel dan indeks polidispersitas dengan menggunakan Particle Size Analized (PSA) serta efisiensi penjeratan sinkonin dengan menggunakan KCKT. Temperatur gelasi (Tg) span 60 45±2 oC, kecepatan rotavapor pembentukan film lapis tipis niosom 210 rpm, temperatur hidrasi 55±2 oC, kecepatan rotavapor hidrasi 210 rpm, waktu hidrasi 20 menit, waktu sonikasi suspensi niosom 1 menit. Ukuran vesikel yang diperoleh adalah 100–200 nm, indeks polidispersitas 0,2–0,4 dan efisiensi penjeratan niosom sinkonin 84,49±0,0025%. Proses pembuatan niosom sinkonin memiliki pengaruh besar terhadap hasil ukuran vesikel dan efisiensi penjeratan niosom sinkonin.

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