The Experts below are selected from a list of 10209 Experts worldwide ranked by ideXlab platform
Igor Krupa - One of the best experts on this subject based on the ideXlab platform.
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Thermal properties of phase-change materials based on high-density polyethylene filled with micro-encapsulated paraffin wax for thermal energy storage
Energy and Buildings, 2015Co-Authors: Mustapha Karkri, Mohamed Lachheb, Bojana Boh, A. Fethi, Zuzana Nogellova, Bostjan Sumiga, Mariam Al Ali Almaadeed, Igor KrupaAbstract:Microcapsules consisting of paraffin wax cores with a melting point of approximately 42 °C and a Melamine-Formaldehyde Resin shell were synthesized using in situ polymerization. These microcapsules have a uniform distribution with a spherical shape and an average diameter of approximately 15 μm. The thickness of the shell was approximately 1.5 μm. Shape-stabilized phase change materials (PCM) based on high-density polyethylene (HDPE) mixed with micro-encapsulated paraffin wax were prepared and investigated for application in thermal energy storage. The distribution of the capsules within the HDPE matrix was uniform without any tendency toward agglomeration. The microencapsulated paraffin wax acts as a high-latent-heat material, whereas the HDPE matrix ensures the compact shape, structural compactness and mechanical strength of the final PCM. The periodic temperature method was used to determine the thermal conductivity and thermal diffusivity of the phase change materials. A guarded hot plate unit was used to determine the latent heats of these phase-change materials. The thermal conductivity and diffusivity of the investigated PCMs decreased as the microcapsule content increased. In contrast, the latent, sensible and total heat of the PCMs increased with the paraffin content.
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phase change materials based on high density polyethylene filled with microencapsulated paraffin wax
Energy Conversion and Management, 2014Co-Authors: Igor Krupa, Zuzana Nogellova, Zdenko Spitalský, Ivica Janigova, Bostjan Sumiga, Angela Kleinova, Mustapha Karkri, Mariam Al Ali AlmaadeedAbstract:Abstract A modified in situ polymerization microencapsulation procedure for the preparation of microcapsules with paraffin wax cores (43 wt.%) and melamine–formaldehyde Resin shells having a uniform size distribution and a spherical shape with average diameters of approximately 15 μm was developed. The high-density polyethylene/microcapsule blends were prepared via two routes. In the first case, the dry high-density polyethylene powder covered by microcapsules was simply hot pressed, whereas, in the second case, the dry high density polyethylene/capsule powder was first blended in the molten state to obtain better homogeneity before hot pressing. It was observed that both systems behave qualitatively the same with comparable mechanical properties and thermal behavior. The thermal stability of high-density polyethylene/microcapsule blends characterized by thermogravimetry is significantly lower than that of neat high-density polyethylene. The selected characteristic temperatures of degradation decreased by more than 200 °C compared with the related temperatures for neat high-density polyethylene. An analysis based on Differential Scanning Calorimetry revealed separated melting and crystallization behavior of wax within the capsules and high density polyethylene in the blends. The enthalpies of melting and crystallization are proportional to the amount of individual components in the material. The capsules have a strong plasticizing effect on the high density polyethylene, resulting in a significant decrease in the melting and crystallization temperatures. The plasticizing effect was also confirmed by measurements of the tensile mechanical properties and rheological behavior.
Xinghua Wang - One of the best experts on this subject based on the ideXlab platform.
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synergistic effects of organically modified montmorillonite on the flame retardant and smoke suppression properties of transparent intumescent fire retardant coatings
Progress in Organic Coatings, 2018Co-Authors: Zhisheng Xu, Xinghua WangAbstract:Abstract A series of novel montmorillonite polyphosphate (OPEA) flame retardants were successfully synthesized by chemical grafting of cyclic phosphate ester acid (PEA) with different contents of organically modified montmorillonite (OMMT). Their chemical structures were confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). Five types of transparent fire-retardant coatings applied to plywood boards were prepared by mixing melamine formaldehyde Resin with PEA or OPEAs. The transparency analysis reveals that chemical grafting of PEA on the surface of OMMT imparts a high degree of transparency to the resulting fire-retardant coatings due to the uniform dispersion and completely exfoliated states of the MMT platelets in the coatings, as determined from X-ray diffraction patterns and transmission electron microscopy images. The fire protection tests show that the introduction of OMMT decreases the mass loss, char index, and flame spread rating of the coatings, concomitant with an increase in the intumescent factor. The cone calorimeter and smoke density tests reveal that incorporation of OMMT remarkably decreases the heat release and smoke production of the coatings, which is ascribed to a more thermally stable, compact and intumescent char layer formed during combustion, judging from digital photographs and scanning electron microscopy images. Further, the synergistic flame-retardant and smoke suppression effects of OMMT in the coatings depend on the content of OMMT, and excessive OMMT will decrease the synergistic effects. The thermo-gravimetric analysis shows that the thermal stability and residual weight of the coatings increase efficiently with increasing OMMT content. The FTIR and elemental analysis demonstrate that the incorporation of OMMT generates more phosphorus-rich cross-linked char and aromatic char in the condensed phase, thus effectively reducing the heat release, smoke production, and mass loss of the coatings.
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influence of nano silica on the flame retardancy and smoke suppression properties of transparent intumescent fire retardant coatings
Progress in Organic Coatings, 2017Co-Authors: Zhisheng Xu, Xinghua WangAbstract:Abstract A cyclic phosphate ester acid (PEA) was synthesized by the reaction of phosphoric acid (PA), pentaerythritol (PER) and n -butyl alcohol (BA). Then nano-silica was successfully introduced into the structure of PEA to obtain SPEAs with different nano-silica contents. The chemical structures of PEA and SPEAs were confirmed by Fourier transform infrared spectroscopy (FTIR) and 1 H nuclear magnetic resonance spectroscopy ( 1 H NMR). A series of fire-retardant coatings coated on the plywood boards were prepared by mixing of melamine formaldehyde Resin with PEA and SPEAs. The transparency analysis indicates that the incorporation of nano-silica into the coatings through chemical grafting method acquires high degree of transparency due to the homogeneous dispersion of each element in the coatings, judging by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The influence of nano-silica on the thermal stability, flame retardancy and smoke suppression properties of coatings were investigated in details by cabinet method test, tunnel method test, cone calorimeter test, smoke density test, thermo-gravimetric analysis (TG), FTIR, SEM and EDS. The results show that the values of weight loss, char index, flame spread rating, heat release rate, total heat release, smoke production rate, total smoke release and specific optical density of the coatings are remarkably decreased with the introduction of nano-silica, which is due to the formation of a compact and intumescent char layer during combustion. The TG results demonstrate that the incorporation of nano-silica increases the thermal stability and residual weight of the coatings. The char residue analysis reveals that the nano-silica enhances the char-forming ability, intumescence and antioxidation property of the coatings due to the synergistic effect existed between phosphorus and silicon, leading to a stronger shielding effect in condensed phase. Based on these facts, the introduction of nano-silica could promote the formation of a more compact and intumescent char layer and then effectively reduces the heat and smoke release, thereby enhancing the flame retardancy and smoke suppression properties of coatings.
Mariam Al Ali Almaadeed - One of the best experts on this subject based on the ideXlab platform.
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Thermal properties of phase-change materials based on high-density polyethylene filled with micro-encapsulated paraffin wax for thermal energy storage
Energy and Buildings, 2015Co-Authors: Mustapha Karkri, Mohamed Lachheb, Bojana Boh, A. Fethi, Zuzana Nogellova, Bostjan Sumiga, Mariam Al Ali Almaadeed, Igor KrupaAbstract:Microcapsules consisting of paraffin wax cores with a melting point of approximately 42 °C and a Melamine-Formaldehyde Resin shell were synthesized using in situ polymerization. These microcapsules have a uniform distribution with a spherical shape and an average diameter of approximately 15 μm. The thickness of the shell was approximately 1.5 μm. Shape-stabilized phase change materials (PCM) based on high-density polyethylene (HDPE) mixed with micro-encapsulated paraffin wax were prepared and investigated for application in thermal energy storage. The distribution of the capsules within the HDPE matrix was uniform without any tendency toward agglomeration. The microencapsulated paraffin wax acts as a high-latent-heat material, whereas the HDPE matrix ensures the compact shape, structural compactness and mechanical strength of the final PCM. The periodic temperature method was used to determine the thermal conductivity and thermal diffusivity of the phase change materials. A guarded hot plate unit was used to determine the latent heats of these phase-change materials. The thermal conductivity and diffusivity of the investigated PCMs decreased as the microcapsule content increased. In contrast, the latent, sensible and total heat of the PCMs increased with the paraffin content.
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phase change materials based on high density polyethylene filled with microencapsulated paraffin wax
Energy Conversion and Management, 2014Co-Authors: Igor Krupa, Zuzana Nogellova, Zdenko Spitalský, Ivica Janigova, Bostjan Sumiga, Angela Kleinova, Mustapha Karkri, Mariam Al Ali AlmaadeedAbstract:Abstract A modified in situ polymerization microencapsulation procedure for the preparation of microcapsules with paraffin wax cores (43 wt.%) and melamine–formaldehyde Resin shells having a uniform size distribution and a spherical shape with average diameters of approximately 15 μm was developed. The high-density polyethylene/microcapsule blends were prepared via two routes. In the first case, the dry high-density polyethylene powder covered by microcapsules was simply hot pressed, whereas, in the second case, the dry high density polyethylene/capsule powder was first blended in the molten state to obtain better homogeneity before hot pressing. It was observed that both systems behave qualitatively the same with comparable mechanical properties and thermal behavior. The thermal stability of high-density polyethylene/microcapsule blends characterized by thermogravimetry is significantly lower than that of neat high-density polyethylene. The selected characteristic temperatures of degradation decreased by more than 200 °C compared with the related temperatures for neat high-density polyethylene. An analysis based on Differential Scanning Calorimetry revealed separated melting and crystallization behavior of wax within the capsules and high density polyethylene in the blends. The enthalpies of melting and crystallization are proportional to the amount of individual components in the material. The capsules have a strong plasticizing effect on the high density polyethylene, resulting in a significant decrease in the melting and crystallization temperatures. The plasticizing effect was also confirmed by measurements of the tensile mechanical properties and rheological behavior.
Hyun-joong Kim - One of the best experts on this subject based on the ideXlab platform.
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H (2006) Antibacterial performance of colloidal silver-treated laminate wood flooring
2020Co-Authors: Sumin Kim, Hyun-joong KimAbstract:Abstract In this study both the anti-bacterial properties and strength of cockroach avoidance of laminate wood floorings containing colloidal silver is evaluated. The laminate wood flooring manufactured with the overlay added with Resin containing colloidal silver ion showed an antibacterial activity of up to 98.9%. For colloidal silver-treated, laminate wood flooring, the relative avoidance rate was 8771%. With colloidal silver treatment onto the surface of the laminate wood flooring, using Melamine-Formaldehyde Resin for overlay paper impregnation, laminate wood flooring was developed as an environmentally friendly material for residential application.
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anti bacterial performance of colloidal silver treated laminate wood flooring
International Biodeterioration & Biodegradation, 2006Co-Authors: Sumin Kim, Hyun-joong KimAbstract:In this study both the anti-bacterial properties and strength of cockroach avoidance of laminate wood floorings containing colloidal silver is evaluated. The laminate wood flooring manufactured with the overlay added with Resin containing colloidal silver ion showed an antibacterial activity of up to 98.9%. For colloidal silver-treated, laminate wood flooring, the relative avoidance rate was 87±1%. With colloidal silver treatment onto the surface of the laminate wood flooring, using Melamine-Formaldehyde Resin for overlay paper impregnation, laminate wood flooring was developed as an environmentally friendly material for residential application.
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comparison of standard methods and gas chromatography method in determination of formaldehyde emission from mdf bonded with formaldehyde based Resins
Bioresource Technology, 2005Co-Authors: Sumin Kim, Hyun-joong KimAbstract:Formaldehyde emissions from MDF bonded with urea-formaldehyde Resin (UF), Melamine-Formaldehyde Resin (MF) and the co-polycondensation Resin of urea-Melamine-Formaldehyde (UMF) and Melamine-Formaldehyde, measured by the Japanese standard method of determining formaldehyde emission with a desiccator (JIS A 5908) and the DIN EN 120 (European Committee For Standardization, 1991) method using the perforator value, were used as the typical standard methods. While the UF Resin showed a desiccator value of 7.05 ppm and a perforator value of 12.1 mg/100 g panel, the MF Resin exhibited a desiccator value of 0.6 ppm and a perforator value of 2.88 mg/100 g panel. According to the Japanese industrial standard and the European standard, the formaldehyde emission level of the MDF panels made with UF Resin in this study was E(2) grade. The formaldehyde emission level was dramatically reduced by the addition of MF Resin. This is because the addition of formaldehyde to melamine occurs more easily and completely than its addition to urea, even though the condensation reaction of melamine with formaldehyde is similar to that between urea and formaldehyde. These two methods, the desiccator method and the perforator method, produced proportionally equivalent results. Gas chromatography, a more sensitive and advanced method, was also used. The samples used for gas chromatography were gathered during the experiment involving the perforator method. The formaldehyde emission levels obtained from gas chromatography were similar to those obtained from the perforator method. The formaldehyde contents measured by gas chromatography were directly proportional to the perforator values.
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Effect of addition of polyvinyl acetate to Melamine-Formaldehyde Resin on the adhesion and formaldehyde emission in engineered flooring
International Journal of Adhesion and Adhesives, 2005Co-Authors: Sumin Kim, Hyun-joong KimAbstract:Abstract The objective of this research was to investigate the effect of adding polyvinyl acetate (PVAc), for reducing the formaldehyde emission level, on the adhesion properties of Melamine-Formaldehyde (MF) Resin for fancy veneer and plywood in engineered flooring. We controlled the hot-press temperature, time and pressure to determine the bonding strength and formaldehyde emission. Blends of various MF Resin/PVAc compositions were prepared. To determine and compare the effect of PVAc content, 0, 30, 50, 70 and 100% PVAc floorings, by weight of MF Resin, were used. Wheat flour, 25% by weight of adhesive, was added as material to increase the quantity. To determine the level of formaldehyde emission, we used the desiccator method. The formaldehyde emission level decreased with increased additions of PVAc. At a PVAc replacement ratio of only 30%, the formaldehyde emission level of the coated sample by UV-curable coat was under E 1 grade. Curing of the high MF Resin content in this adhesive system (MF Resin with PVAc) was well processed indicating that the bonding strength was increased. In the case of PVAc only, the bonding strength was much lower due to the already high temperature of 120 °C. The adhesion layer was broken by high temperature and pressure. The sample with 30% PVAc added to MF Resin (MF Resin: PVAc=70:30) showed good bonding strength compared with MF Resin only in all cases, hot-press temperature, time, pressure and boiling test.
Mustapha Karkri - One of the best experts on this subject based on the ideXlab platform.
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Thermal properties of phase-change materials based on high-density polyethylene filled with micro-encapsulated paraffin wax for thermal energy storage
Energy and Buildings, 2015Co-Authors: Mustapha Karkri, Mohamed Lachheb, Bojana Boh, A. Fethi, Zuzana Nogellova, Bostjan Sumiga, Mariam Al Ali Almaadeed, Igor KrupaAbstract:Microcapsules consisting of paraffin wax cores with a melting point of approximately 42 °C and a Melamine-Formaldehyde Resin shell were synthesized using in situ polymerization. These microcapsules have a uniform distribution with a spherical shape and an average diameter of approximately 15 μm. The thickness of the shell was approximately 1.5 μm. Shape-stabilized phase change materials (PCM) based on high-density polyethylene (HDPE) mixed with micro-encapsulated paraffin wax were prepared and investigated for application in thermal energy storage. The distribution of the capsules within the HDPE matrix was uniform without any tendency toward agglomeration. The microencapsulated paraffin wax acts as a high-latent-heat material, whereas the HDPE matrix ensures the compact shape, structural compactness and mechanical strength of the final PCM. The periodic temperature method was used to determine the thermal conductivity and thermal diffusivity of the phase change materials. A guarded hot plate unit was used to determine the latent heats of these phase-change materials. The thermal conductivity and diffusivity of the investigated PCMs decreased as the microcapsule content increased. In contrast, the latent, sensible and total heat of the PCMs increased with the paraffin content.
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phase change materials based on high density polyethylene filled with microencapsulated paraffin wax
Energy Conversion and Management, 2014Co-Authors: Igor Krupa, Zuzana Nogellova, Zdenko Spitalský, Ivica Janigova, Bostjan Sumiga, Angela Kleinova, Mustapha Karkri, Mariam Al Ali AlmaadeedAbstract:Abstract A modified in situ polymerization microencapsulation procedure for the preparation of microcapsules with paraffin wax cores (43 wt.%) and melamine–formaldehyde Resin shells having a uniform size distribution and a spherical shape with average diameters of approximately 15 μm was developed. The high-density polyethylene/microcapsule blends were prepared via two routes. In the first case, the dry high-density polyethylene powder covered by microcapsules was simply hot pressed, whereas, in the second case, the dry high density polyethylene/capsule powder was first blended in the molten state to obtain better homogeneity before hot pressing. It was observed that both systems behave qualitatively the same with comparable mechanical properties and thermal behavior. The thermal stability of high-density polyethylene/microcapsule blends characterized by thermogravimetry is significantly lower than that of neat high-density polyethylene. The selected characteristic temperatures of degradation decreased by more than 200 °C compared with the related temperatures for neat high-density polyethylene. An analysis based on Differential Scanning Calorimetry revealed separated melting and crystallization behavior of wax within the capsules and high density polyethylene in the blends. The enthalpies of melting and crystallization are proportional to the amount of individual components in the material. The capsules have a strong plasticizing effect on the high density polyethylene, resulting in a significant decrease in the melting and crystallization temperatures. The plasticizing effect was also confirmed by measurements of the tensile mechanical properties and rheological behavior.