Simultaneous prediction of density and moisture content of wood by terahertz time domain spectroscopy

Inagaki, Toru; Ahmed, Belal; Hartley, Ian D.; Tsuchikawa, Satoru; Reid, M.

doi:10.1007/s10762-014-0095-7

Cited by 37 publications

(24 citation statements)

References 24 publications

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“…Likewise, Δκ is described as Equation (4) The difference between calculated and measured Δn 0.4 may be attributed to free and bound water in the specimen because THz radiation is sensitive to both water states [18][19][20][21][22][23][24][25][26]. Since amine cured EP resins have some hydrophilic groups such as hydroxyl groups and amine groups, water becomes bound to such groups to some extent.…”

Section: Discussionmentioning

confidence: 99%

“…The main advantages of THz-TDS for NDT studies are the high penetration of THz electromagnetic waves into polymers [13][14][15][16][17][18], high sensitivity to the inter/intra molecular vibrations (especially for water) [18][19][20][21][22][23][24][25][26], and ability to estimate the materials dielectric properties without direct contact [27][28][29]. The THz spectra of various thermoplastics [13][14][15] and thermosets [16,17] measured by THz-TDS were reported.…”

mentioning

confidence: 99%

“…For example, the amounts of water in polyamide and wood plastic composites were estimated with THz-TDS by measuring the complex refractive index as a function of water content [18]. In the case of wood materials in humid environment, the real and imaginary parts of the complex dielectric function of the samples strongly correlated with density and moisture content [21]. As described above, the interpretation of THz spectra for penetrants in polymer still remains unclear but if penetrants such as sulfuric acid in polymer affect THz spectra, THz spectroscopy may help to nondestructively monitor polymer degradation by corrosive solution penetration and evaluate the penetrant content in polymer.…”

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confidence: 99%

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Non-destructive evaluation by terahertz spectroscopy for penetration of acid solutions into epoxy resin

Kusano¹,

Kubouchi²,

Bulgarevich³

et al. 2016

Express Polym. Lett.

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Abstract. Epoxy resins are used as high-performance thermosetting linings to protect substrates under corrosive environments. However, in a severe corrosive chemical solution, such protective layers may degrade with long time due to penetrations of solvent and solute molecules into resin network. In this regard, the terahertz time-domain spectroscopy (THz-TDS) is a promising tool for non-destructive evaluation of the penetrant amounts due to high transparency of such plastic materials and high sensitivity to the molecular vibrations in terahertz spectral range. In this work, the complex refractive indexes n and κ of epoxy specimens were measured after immersion into sulfuric acid solutions and compared with penetrated mass fractions of water and acid ions. It was found that n and κ depended linearly with water and sulfuric acid mass fraction in specimens, and κ of sulfuric acid immersed specimens was lager at higher frequency. While the calculated Δκ agreed well with THz-TDS measurement by THz-TDS, the calculated Δn was higher than the measurement. The difference may be attributed to the water and sulfuric states in the specimen.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Non-destructive evaluation by terahertz spectroscopy for penetration of acid solutions into epoxy resin

Kusano¹,

Kubouchi²,

Bulgarevich³

et al. 2016

Express Polym. Lett.

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“…Del mismo modo, se logró apreciar una tendencia de disminución del contenido de humedad respecto al aumento de temperatura de los tratamientos (cuadro 1), Inagaki et al (2014) indicó la existencia de una fuerte relación entre la densidad de la madera y su contenido de humedad, es decir, a medida que aumenta el contenido de humedad aumenta la densidad. No obstante, ese comportamiento no fue obtenido en este estudió lo que se puede deber a las pérdidas de humedad generadas en el proceso de termo-tratamiento.…”

Section: Discussionunclassified

Determinación del módulo de elasticidad por los métodos dinámico y estático para madera termo-tratada de Gmelina arborea y Tectona grandis

Méndez-Mejías

2015

RFMK

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<p>Se estudió el efecto del tratamiento térmico sobre el módulo de elasticidad (MOE) de la madera para dos especies forestales Gmelina arborea (melina) y Tectona grandis (teca). Las muestras fueron expuestas a cuatro niveles de temperatura 160, 180, 200 y 220 °C por 2 horas, además se definió un tratamiento testigo (sin termo-tratamiento). A las muestras sometidas al tratamiento térmico se les determinó el módulo de elasticidad por ultrasonido (EUS) en sentido transversal y longitudinal y módulo de elasticidad en flexión estática (EES). Asimismo, se determinó la densidad y contenido de humedad (CH). Los resultados mostraron que la densidad varió entre 444,32 a 531,54 kg/m3 y de 594,11 a 697,25 kg/m3 para melina y teca respectivamente. El CH fluctuó de 3,77 a 11,47 % y de 2,90 a 8 % para melina y teca respectivamente, con una tendencia a disminuir conforme aumenta la temperatura de termo-tratamiento en las piezas. El EUS en sentido transversal varió de 1,16 a 2,35 GPa, el EUS en sentido longitudinal varió de 9,80 a 12,53 GPa y el EES fluctúo de 6,15 a 7,98 GPa, para melina. Para teca los resultados variaron de 1,90 a 3,07 GPa para EUS en sentido transversal, de 16,13 a 18,12 GPa para EUS en sentido longitudinal y de 9,41 a 11,47 GPa para EES. Finalmente, se obtuvo que los mejores valores de MOE para melina corresponde a los tratamientos de 160 y 180 °C de temperatura. En tanto para teca, corresponden a los tratamientos con 180 y 200 °C de temperatura.</p>

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“…The species used in this study were maple (Acer saccharum) , birch (Betula spp) and western hemlock ( Tsuga heterophylla), and were taken from samples initially prepared by T. Inagaki [44]. These samples were selected to give reasonable variation in species density and wood type (softwood versus hardwood).…”

Section: Sample Preparationmentioning

confidence: 99%

Single-frequency terahertz Michelson interferometer for applications in wood products

Lawyer¹

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There is an ever-growing demand in the wood products industry for cost-effective and compact equipment to ensure wood quality measures and specifications are met. Recently, terahertz (THz) technology has begun to pave the way for new , non-destructive imaging techniques rather than the standard use of X-ray or microwave technology.A prototype THz Michelson interferometer operating at 0.102 THz was developed to measure the indices of refraction and absorption coeffi cients of maple, hemlock and birch. These measurements were compared to the Picometrix system, which uses conventional THz time-domain spectroscopy and has been implemented in an industrial setting for the real-time measurement of the density of OSB flakes . However , the cost and complexity of the Picometrix system prohibits its use for many industrial applications. The interferometer is cost-effective, compact and provides accurate data at low THz frequencies , thus providing an excellent alternative direction for new THz technology in the wood products industry.

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Simultaneous prediction of density and moisture content of wood by terahertz time domain spectroscopy

Cited by 37 publications

References 24 publications

Non-destructive evaluation by terahertz spectroscopy for penetration of acid solutions into epoxy resin

Non-destructive evaluation by terahertz spectroscopy for penetration of acid solutions into epoxy resin

Determinación del módulo de elasticidad por los métodos dinámico y estático para madera termo-tratada de Gmelina arborea y Tectona grandis

Single-frequency terahertz Michelson interferometer for applications in wood products

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