Effect of elastic modulus and position of polyurea coating on flexural strength of coated ceramic tiles by experiments and finite element analysis / Kanittha Kamonchaivanich in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 16, N° 4 (07/2019)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 16, N° 4 (07/2019) . - p. 1201-1211 Titre : Effect of elastic modulus and position of polyurea coating on flexural strength of coated ceramic tiles by experiments and finite element analysis Type de document : texte imprimé Auteurs : Kanittha Kamonchaivanich, Auteur ; Keiichi Kuboyama, Auteur ; Toshiaki Ougizawa, Auteur Année de publication : 2019 Article en page(s) : p. 1201-1211 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Elasticité Flexion (mécanique) Flexion trois points Matériaux céramiques Polyurée Revêtements -- Propriétés mécaniques Revêtements organiques Index. décimale : 667.9 Revêtements et enduits Résumé : The mechanism of a polyurea coating on the flexural strength of coated ceramic tiles was studied by three-point bending together with FEM simulation. The influence of Young’s modulus and the coating position of the polyurea on the coated ceramic sample were investigated. The back-coated ceramic with lower modulus polyurea (PUR240 MPa) could show higher flexural strength due to the cushion effect that reduces tensile stress around the bottom center of the substrate. The higher modulus polyurea coating (PUR866 MPa) has a significant influence on the flexural strength of the coated ceramic sample. In back-coating, the higher modulus coating increased the flexural strength of the coated ceramic sample by nearly twofold, compared to lower modulus. This higher modulus coating enhanced the stress distribution as well as storage energy in the sample. According to the results of the FEM simulation, the mechanism which influences the stress distribution within samples during the three-point bending test was investigated. The cushion effect shows a main contribution in stress distribution by a lower modulus coating. The cushion effect occurs near the supporting pins and contributes to the stress dissipation and the reduction of stress concentration at the center-bottom of the substrate. In contrast, a thickening effect plays an important role in the case of higher modulus polyurea coatings. The center-back-coated with higher modulus polyurea acts to increase the thickness of the ceramics and dominates the effect on the flexural strength of the coated ceramic sample. Note de contenu : - EXPERIMENTAL : Materials - Sample preparation - Three-point bending test - Strain measurement - Simulation by finite element method (FEM) - Input parameters - RESULTS AND DISCUSSION : Effects of elastic modulus of coating on the flexural strength by three-point bending - Analysis of elastic modulus effect of coating by finite element method - Effects of partial back coating on flexural strength of ceramic sample - Effects of partial back coating with different elastic modulus polyurea coating by finite element method DOI : 10.1007/s11998-018-00170-6 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-018-00170-6.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32874 [article]

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A tunable controlled-release urea fertilizer coated with a biodegradable polyurethane-nanoclay composite layer / Kannika Sitthisuwannakul in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 20, N° 2 (03/2023)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 20, N° 2 (03/2023) . - p. 635-646 Titre : A tunable controlled-release urea fertilizer coated with a biodegradable polyurethane-nanoclay composite layer Type de document : texte imprimé Auteurs : Kannika Sitthisuwannakul, Auteur ; Kanittha Kamonchaivanich, Auteur ; Thanakorn Wirunmongkol, Auteur ; Pennapa Muthitamongkol, Auteur ; Wiyong Kangwansupamonkon, Auteur Année de publication : 2023 Article en page(s) : p. 635-646 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Angle de contact Argile Biodégradation Caractérisation Coefficient de diffusion Un coefficient de diffusion est une grandeur caractéristique du phénomène de diffusion de la matière. Le coefficient de diffusion mesure le rapport entre le flux molaire dû à la diffusion moléculaire, et le gradient de concentration de l'espèce chimique considérée (ou, plus généralement, de la variable d'effort entraînant cette diffusion), comme formulé par la loi de Fick. Engrais organiques Nanoparticules Polyuréthanes Revêtements -- Propriétés chimiques Revêtements -- Propriétés mécaniques Revêtements -- Propriétés physiques Revêtements organiques Système de libération contrôlée (technologie) Urée Index. décimale : 667.9 Revêtements et enduits Résumé : To minimize a loss of urea to the environment and also control a release activity, a tunable and controlled-release urea fertilizer (TCRF) was created. Composite coating layers of the TCRF were synthesized using a composite of nanoclay (B27), and a linseed oil-modified polyurethane resin (BURNOCK® UL65). The concentration of B27 nanoclay was varied from 0, 3, 5 and 10 wt% and called TCRF, TCRF-3, TCRF-5 and TCRF-10, respectively. Firstly, nanocomposite free-standing films (NFs) with 0, 0.5, 1, 3, 5 and 10 wt% of B27 were synthesized and tested to demonstrate the mechanical properties of the coating layer. When the B27 clay content increased, the Young’s modulus and yield strength were increased. On the other hand, the elongation at break was decreased. NFs were also characterized by XRD and TEM, which showed a partial exfoliated nanocomposite character. The water contact angle measurement showed that all NFs had hydrophobicity properties (87°–90° contact angle). Moreover, the microorganism degradability test showed that the NFs degraded at 37 ± 2°C and 58 ± 2°C in manure, a common agriculture media. The study on coated urea fertilizers found that the thickness of all TCRFs layers is around 52–54 μm. The nitrogen release profiles of the TCRF at 60°C in water as a predictive analytic model were investigated using an elemental analyzer that is a pathway analysis method to understand the release profiles of the TCRFs. All release profiles fitted well with the sigmoidal model, which was suitable for a common plant growth. The profiles gave diffusion coefficients (D) in the range of 49–69 μm2 h−1 and presented an inverse trend to the yield strength of the NFs. The investigation demonstrated that B27 played an important role in tuning the strength of the coating layers that affected the urea release to the plants and the environment. Note de contenu : - MATERIALS AND METHODS : Chemicals - Nanocomposite free-standing films (NFS) preparation - Biodegradability analysis of the NF - Tunable controlled-release urea fertilizer (TCRF) preparation - Characterizations - Nitrogen release test and kinetic study of TCRF - RESULTS AND DISCUSSION : Swelling performance and the characteristics of the nanoclays - Chemical and physical properties of the NF - Biodegradable ability - Nitrogen release mechanism - Table 1 : Mechanical properties and contact angles of NF nanocomposite films - Table 2 : The percentages of biodegradation via the conversion yield of carbon in the sample to carbon dioxide according to the ASTM 5338–98 test method - Table 3 : Kinetic parameters and diffusion coefficients of various types of TCRF DOI : https://doi.org/10.1007/s11998-022-00688-w En ligne : https://link.springer.com/content/pdf/10.1007/s11998-022-00688-w.pdf?pdf=button Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39308 [article]

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