scholarly journals Study on the thermal properties and insulation resistance of epoxy resin modified by hexagonal boron nitride

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 681-690
Author(s):  
Lei Guo ◽  
Shilin Ding ◽  
Shuai Yuan ◽  
Xiaofeng Gou ◽  
Fenglin Cai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Composite ◽  
Hexagonal Boron Nitride ◽  
Volume Resistivity ◽  
Epoxy Composites ◽  
Insulation Resistance ◽  
Insulation Performance

Abstract To study the effect of doping hexagonal boron nitride (h-BN) on the thermal properties and insulation resistance of epoxy resin (EP) and the mechanism of this effect, h-BN/epoxy composites with h-BN content of 0, 10, 20, 30, and 40 phr were prepared. Meanwhile, the corresponding molecular dynamics model of h-BN/epoxy composites was established, and the thermal conductivity, volume resistivity, glass transition temperature, and microstructure parameters of h-BN/epoxy composites were obtained. When the h-BN content is 40 phr, the thermal conductivity of h-BN/epoxy composite is increased by 138% compared to pure EP, and the glass transition temperature is increased by 76 K. At the same time, doping h-BN will reduce the insulation performance of EP. However, the lowest volume resistivity of h-BN/epoxy composite is still 1.43 × 1015 Ω·cm, and the EP composite still has good insulation performance. The fraction free volume and mean square displacement of EP decrease with the doping of h-BN, which indicates that h-BN can hinder the movement of molecular segments of EP, which is the reason for the increase in glass transition temperature.

Preparation and Properties of Modified Boron Nitride/Epoxy Resin Thermal Conductive Composites

2020 ◽  
Vol 1003 ◽  
pp. 173-178
Author(s):  
Chen Liu ◽  
Hao Ran Zhou ◽  
Zhen Yuan
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Boron Nitride ◽  
Epoxy Composite ◽  
Conductive Filler ◽  
Decomposition Temperature ◽  
Thermal Stability Of

Boron nitride (BN) was modified by silane coupling agent (KH560) and used as heat conductive filler to prepare the modified BN (BN560)/epoxy composite. The effect of the BN560 filler content on the thermal conductivity and thermal stability of the epoxy composite was studied. The results show that BN560 can be uniformly dispersed in the epoxy matrix by an ultrasonic disperser. The BN560 added can effectively improve the thermal conductivity of the epoxy composite. With the increase of BN560 content to 20 wt.%, the thermal conductivity of the composite increases accordingly to 0.27 W/(m·K), 50% higher than that of pure epoxy, and a heat conductive network is formed. The BN560 added can improve the thermal stability of the composite. With increasing BN560 content, the thermal decomposition temperature and glass transition temperature of the composite increase. The composite with the BN560 content of 20 wt.% has the weight loss of 10 wt.% at 395.12 °C and the glass transition temperature of 144.59 °C.

scholarly journals Mechanical, Thermal, and Electrical Properties of BN–Epoxy Composites Modified with Carboxyl-Terminated Butadiene Nitrile Liquid Rubber

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1548 ◽  
Author(s):  
Xingming Bian ◽  
Rui Tuo ◽  
Wei Yang ◽  
Yiran Zhang ◽  
Qing Xie ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Epoxy Composite ◽  
Resin Matrix ◽  
Liquid Rubber

Filled high thermal conductivity epoxy composite solves the problem of the low thermal conductivity of the epoxy resin itself, but the addition of the thermal conductive filler reduces the mechanical properties of the composite, which limits its application in the field of high voltage insulation. In this work, carboxyl-terminated butadiene nitrile liquid rubber (CTBN) was used to toughen the boron nitride-epoxy hybrid system, and the effects of different contents of CTBN on the mechanical properties, thermal conductivity, glass transition temperature, thermal stability, and dielectric properties of the composites were investigated. The results showed that when the content of CTBN was 5–15 wt.%, the CTBN formed a dispersed island structure in the epoxy resin matrix. The toughness of the composite increased by about 32%, the breakdown strength was improved, and the thermal conductivity was about 160% higher than that of pure epoxy resin. As the CTBN content increased, the glass transition temperature and thermal stability of the composite decreased and the dielectric constant and the dielectric loss increased. When the CTBN content is 10–15 wt.%, a toughened epoxy composite material with better comprehensive properties is obtained.

scholarly journals Densification: A Route towards Enhanced Thermal Conductivity of Epoxy Composites

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 286
Author(s):  
Sasan Moradi ◽  
Frida Román ◽  
Yolanda Calventus ◽  
John M. Hutchinson
Keyword(s):  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Room Temperature ◽  
Epoxy Composite ◽  
Amorphous Polymer ◽  
Ambient Pressure ◽  
Average Size ◽  
Enhanced Thermal Conductivity

When an amorphous polymer is cooled under pressure from above its glass transition temperature to room temperature, and then the pressure is released, this results in a densified state of the glass. This procedure applied to an epoxy composite system filled with boron nitride (BN) particles has been shown to increase the density of the composite, reduce its enthalpy, and, most importantly, significantly enhance its thermal conductivity. An epoxy-BN composite with 58 wt% BN platelets of average size 30 µm has been densified by curing under pressures of up to 2.0 MPa and then cooling the cured sample to room temperature before releasing the pressure. It is found that the thermal conductivity is increased from approximately 3 W/mK for a sample cured at ambient pressure to approximately 7 W/mK; in parallel, the density increases from 1.55 to 1.72 ± 0.01 g/cm3. This densification process is much more effective in enhancing the thermal conductivity than is either simply applying pressure to consolidate the epoxy composite mixture before curing or applying pressure during cure but then removing the pressure before cooling to room temperature; this last procedure results in a thermal conductivity of approximately 5 W/mK. Furthermore, it has been shown that the densification and corresponding effect on the thermal conductivity is reversible; it can be removed by heating above the glass transition temperature and then cooling without pressure and can be reinstated by again heating above the glass transition temperature and then cooling under pressure. This implies that a densified state and an enhanced thermal conductivity can be induced even in a composite prepared without the use of pressure.

A Novel Poly(Ionic Liquid) as the Thermal Insulating Material

2020 ◽  
Vol 13 (3) ◽  
pp. 241-247
Author(s):  
Wenxin Wei ◽  
Guifeng Ma ◽  
Hongtao Wang ◽  
Jun Li
Keyword(s):  
Thermal Conductivity ◽  
Ionic Liquid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flame Resistance ◽  
Insulating Material ◽  
Low Thermal Conductivity ◽  
Thermal Insulating ◽  
Poly Ionic Liquid

Objective: A new poly(ionic liquid)(PIL), poly(p-vinylbenzyltriphenylphosphine hexafluorophosphate) (P[VBTPP][PF6]), was synthesized by quaternization, anion exchange reaction, and free radical polymerization. Then a series of the PIL were synthesized at different conditions. Methods: The specific heat capacity, glass-transition temperature and melting temperature of the synthesized PILs were measured by differential scanning calorimeter. The thermal conductivities of the PILs were measured by the laser flash analysis method. Results: Results showed that, under optimized synthesis conditions, P[VBTPP][PF6] as the thermal insulator had a high glass-transition temperature of 210.1°C, high melting point of 421.6°C, and a low thermal conductivity of 0.0920 W m-1 K-1 at 40.0°C (it was 0.105 W m-1 K-1 even at 180.0°C). The foamed sample exhibited much low thermal conductivity λ=0.0340 W m-1 K-1 at room temperature, which was comparable to a commercial polyurethane thermal insulating material although the latter had a much lower density. Conclusion: In addition, mixing the P[VBTPP][PF6] sample into polypropylene could obviously increase the Oxygen Index, revealing its efficient flame resistance. Therefore, P[VBTPP][PF6] is a potential thermal insulating material.

Robust Nanocomposite Coatings Inspired by Structures of Nacre

2018 ◽  
Author(s):  
Zachary Kockerbeck ◽  
Majid TabkhPaz ◽  
Simon Park ◽  
Ron Hugo
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Composite Coating ◽  
Performance Enhancement ◽  
Gas Permeability ◽  
Hexagonal Boron Nitride ◽  
Nanocomposite Coatings ◽  
Material Strength ◽  
Coating Application

Carbon steel piping can be exposed to environments that contain various chemical and organic elements that induce corrosion and cracking events. This can lead to the loss of fluid into surrounding sensitive and remote environments. To minimize this inherent risk, various coating technologies have been utilized over the years in industry. These coatings typically suffer from complex application methods, high application cost, and vulnerabilities to environmental effects such as mechanical damage and cathodic disbondment. To overcome these challenges, a novel epoxy based composite coating that utilizes the properties of various nano-particulates such as graphene nanoplatelets (GnP), multi-walled carbon nanotubes (MWCNTs), chitosan, and hBN (Hexagonal boron nitride) is developed. These nanoparticles create a nano-scale “brick and mortar” type effect that is analogous to various natural structures such as the abalone shell (nacre). These nano-structures also enhance coating performance by increasing mechanical strength and anti-bacterial properties while simultaneously decreasing gas permeability. This performance enhancement serves to reduce overall corrosion-induced disbondment area. The dispersion of nanoparticles is verified using various microscopy methods such as scanning election microscopy and an optical 3D profilometer. To confirm the role of nanoparticles in the epoxy composite, the samples undergo rigorous testing to determine both mechanical properties as well as the feasibility of coating application, in particular, for use on girth welds. Using a dynamic mechanical analysis (DMA), the material strength of each combination of nanocomposites is tested and used to determine the glass transition temperature. The testing also includes abrasion, and both long-term mechanical and thermal behaviors of the coating. To test the feasibility of the coating, cathodic protection tests in an accelerated corrosive environment, and gas permeability tests are carried out. The results show that the composite coating made from these nanomaterials had a decrease in cathodic disbondment area and gas permeability and an increase the glass transition temperature and scratch resistance. Therefore, the nanocomposite coatings are found to be a significant improvement over standard epoxy-based coating.

Thermo-mechanical properties and thermal conductivity of CdS-trans-polyisoprene, polymer nanocomposite

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Mahesh Baboo ◽  
Manasvi Dixit ◽  
Dinesh Patidar ◽  
Kananbala Sharma ◽  
Narendra Sahai Saxena
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Storage Modulus ◽  
Structural Changes ◽  
Polymer Nanocomposite ◽  
Cds Nanoparticles ◽  
Chemical Route

Abstract This paper focuses on the comparative evaluation of the glass transition temperature (Tg), storage modulus and thermal conductivity of trans-polyisoprene (TPI) and CdS-TPI nanocomposite. The CdS nanoparticles synthesized by chemical route are dispersed into TPI using ultrasonic vibrations. Particle size of nanocrystals is obtained from X-ray diffraction and found to be 1.84 nm. Thermo-mechanical properties (Tg and storage modulus) are measured by dynamic mechanical analyzer (DMA), while thermal conductivity is a measured using the transient plane source (TPS) technique. It is observed that glass transition temperature and thermal conductivity are higher while storage modulus and mechanical properties are lower for CdS-TPI nanocomposites than for pure TPI. This has been explained on the basis of structural changes occurring due to introduction of CdS as filler into the TPI.

scholarly journals Thermal and thermodynamic characterization of a dye powder from liquid turmeric extracts by spray drying

2016 ◽  
Vol 69 (1) ◽  
pp. 7845-7854 ◽  
Author(s):  
Aura Yazmin Coronel Delgado ◽  
Héctor José Ciro Velásquez ◽  
Diego Alonso Restrepo Molina
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mass Loss ◽  
Spray Drying ◽  
Transient Flow ◽  
Sorption Isotherms

This study aimed to evaluate the thermodynamic properties of sorption isotherms and glass transition temperature (Tg) and the thermal properties of a dye powder obtained from turmeric extracts using spray drying. The sorption isotherms were evaluated at 15, 25 and 35 °C using the dynamic gravimetric method, wherein the isotherm data of the experiment were fit to GAB and BET models. Likewise, the Tg was measured using differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) was used to determine the mass loss, and the thermal properties (heat capacity, diffusivity and thermal conductivity) were determined using transient flow method. The results demonstrated that the GAB model best fit the adsorption data. The DSC analysis presented a glass transition temperature of 65.35 °C and a loss of volatiles at 178.07 °C. The TGA analysis indicated a considerable mass loss starting at 193 °C, resulting in degradation of the product. The thermal properties demonstrated a heat capacity of 2.45 J/g °C, a thermal conductivity of 0.164 ± 0.001 W/mK and a thermal diffusivity of 8.7x10-8 ± 0.000 m2/s.

scholarly journals PROPERTIES OF EPOXY COMPOSITES CURED BY A COMPLEX OF ORGANIC TIN HALIDE WITH AN AMINOPHENOL HARDENER

2020 ◽  
Vol 5 (11) ◽  
pp. 89-101
Author(s):  
Y. Kochergin ◽  
A. Nosova ◽  
T. Kravchuk ◽  
T. Grigorenko ◽  
V. Zolotareva
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Water Environment ◽  
Strength Properties ◽  
Epoxy Composites ◽  
Antifouling Coatings ◽  
Hydraulic Equipment ◽  
Deformation Ability ◽  
Low Exposure

A method for the synthesis of a complex based on an organic tin halide – dibutylol dibromide – and a aminophenol hardener of the UP-583 brand has been developed. It is found that samples cured with a complex hardener at room temperature are characterized by lower values of tensile strength, elastic modulus and glass transition temperature compared to samples cured with the original hardener UP-583. The values of strain at break are approximately the same for both hardeners. After heat treatment, the strength and modulus values for samples containing the complex sharply increase, as a result of which they are superior to samples based on UP-583. The deformation capacity does not change much, the glass transition temperature increases after heating, but remains significantly lower than for samples cured with the original UP-583. The observed change in the deformation and strength properties of samples during their exposure in a liquid medium is explained by the superposition of the effects of plasticization and re-hardening of epoxy polymers. At low exposure times, the action of the sorbed moisture is mainly aimed at weakening the intermolecular interaction in the sample. In result, its strength decreases and deformability increases. At large values of exposure times, when the amount of sorbed water becomes sufficiently large and a fairly intense molecular mobility develops, pre-hardening processes prevail, leading to an increase in the cross-linking density and, to a decrease in the deformation ability and an increase in the strength index. It is shown that epoxy composites containing a complex hardener are characterized by good performance in the water environment, increased resistance to the development of fungi and mold, as well as better fire resistance. The studied polymers are promising for obtaining antifouling coatings based on them for hydraulic equipment, sea and river vessels.

scholarly journals Thermal Insulation and Mechanical Properties of Polylactic Acid (PLA) at Different Processing Conditions

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2091
Author(s):  
Mohamed Saeed Barkhad ◽  
Basim Abu-Jdayil ◽  
Abdel Hamid I. Mourad ◽  
Muhammad Z. Iqbal
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polylactic Acid ◽  
Thermal Insulation ◽  
Annealing Time ◽  
Insulation Material ◽  
Thermal Insulation Material

This work aims to provide an extensive evaluation on the use of polylactic acid (PLA) as a green, biodegradable thermal insulation material. The PLA was processed by melt extrusion followed by compression molding and then subjected to different annealing conditions. Afterwards, the thermal insulation properties and structural capacity of the PLA were characterized. Increasing the annealing time of PLA in the range of 0–24 h led to a considerable increase in the degree of crystallization, which had a direct impact on the thermal conductivity, density, and glass transition temperature. The thermal conductivity of PLA increased from 0.0643 W/(m·K) for quickly-cooled samples to 0.0904 W/(m·K) for the samples annealed for 24 h, while the glass transition temperature increased by approximately 11.33% to reach 59.0 °C. Moreover, the annealing process substantially improved the compressive strength and rigidity of the PLA and reduced its ductility. The results revealed that annealing PLA for 1–3 h at 90 °C produces an optimum thermal insulation material. The low thermal conductivity (0.0798–0.0865 W/(m·K)), low density (~1233 kg/m3), very low water retention (<0.19%) and high compressive strength (97.2–98.7 MPa) in this annealing time range are very promising to introduce PLA as a green insulation material.

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