Quantification of diffuse scattering in glass and polymers by parametric power law analysis of UV to NIR light

Tsu, D. V.; Muehle, Matthias; Becker, Michael F.; Schuelke, Thomas; Slagter, John

doi:10.1016/j.surfcoat.2017.08.054

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…Shorter NIR wavelengths are also more strongly affected by light scattering and sample color. The effects of scattering are however complicated due to the presence of absorbing constituents and variation in physical properties such as particle size and shape, surface properties and sample packing 21 , 22 . Increasing carbonization temperature generally leads to a higher carbon content and a darker sample color, which can manifest as increased absorbance on shorter wavelengths 23 .…”

Section: Resultsmentioning

confidence: 99%

Hyperspectral near infrared imaging quantifies the heterogeneity of carbon materials

Mäkelä

Geladi

2018

Sci Rep

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For many applications heterogeneity is a direct indicator of material quality. Reliable determination of chemical heterogeneity is however not a trivial task. Spectral imaging can be used for determining the spatial distribution of an analyte in a sample, thus transforming each pixel of an image into a sampling cell. With a large amount of image pixels, the results can be evaluated using large population statistics. This enables robust determination of heterogeneity in biological samples. We show that hyperspectral imaging in the near infrared (NIR) region can be used to reliably determine the heterogeneity of renewable carbon materials, which are promising replacements for current fossil alternatives in energy and environmental applications. This method allows quantifying the variation in renewable carbon and other biological materials that absorb in the NIR region. Reliable determination of heterogeneity is also a valuable tool for a wide range of other chemical imaging applications.

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Section: Resultsmentioning

confidence: 99%

Hyperspectral near infrared imaging quantifies the heterogeneity of carbon materials

Mäkelä

Geladi

2018

Sci Rep

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“…In contrast to laser heating applications, the radiation emitted by an IR source and transferred through a polymer medium is not monochromatic, but in a range, which introduces such a complexity in terms of modeling of optical scattering, as the scattering behavior may change under varying wavelength in the spectral range of emitted radiation. Such a wavelength-dependent scattering behavior in semi-crystalline polymers was discussed in [5,6].…”

Section: Introductionmentioning

confidence: 98%

Cost-effective computational method for radiation heat transfer in semi-crystalline polymers

Boztepe¹,

Gilblas²,

Almeida³

et al. 2018

AIP Conference Proceedings

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This paper introduces a cost-effective numerical model for infrared (IR) heating of semi-crystalline polymers. For the numerical and experimental studies presented here semi-crystalline polyethylene (PE) was used. The optical properties of PE were experimentally analyzed under varying temperature and the obtained results were used as input in the numerical studies. The model was built based on optically homogeneous medium assumption whereas the strong variation in the thermo-optical properties of semi-crystalline PE under heating was taken into account. Thus, the change in the amount radiative energy absorbed by the PE medium was introduced in the model induced by its temperaturedependent thermo-optical properties. The computational study was carried out considering an iterative closed-loop computation, where the absorbed radiation was computed using an in-house developed radiation heat transfer algorithm-RAYHEAT-and the computed results was transferred into the commercial software-COMSOL Multiphysics-for solving transient heat transfer problem to predict temperature field. The predicted temperature field was used to iterate the thermo-optical properties of PE that varies under heating. In order to analyze the accuracy of the numerical model experimental analyses were carried out performing IR-thermographic measurements during the heating of the PE plate. The applicability of the model in terms of computational cost, number of numerical input and accuracy was highlighted.

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“…Such a wavelength-dependent scattering behavior in semi-crystalline polymers was discussed in Refs. [4,5,12]. The common point that was stressed out in those studies is that the scattering behavior becomes weaker considering an increase in the wavelengths roughly between 0.5 μm and 2 μm, which lies in the visible (VIS) and near-infrared (NIR) ranges.…”

Section: Introductionmentioning

confidence: 99%

A combined experimental and numerical approach for radiation heat transfer in semi-crystalline thermoplastics

Boztepe

Almeida

Gilblas

et al. 2019

International Journal of Thermal Sciences

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This paper proposes a novel experimental-numerical approach for radiation heat transfer in semi-crystalline thermoplastics. The proposed experimental and numerical approaches were analyzed here for the case of IR heating of linear polyethylene (PE). The challenges for radiation transport in semi-crystalline polymers may be categorized into the two main aspects: optical heterogeneity in polymer medium due to semi-crystalline nature and, semi-transparency in certain type of such polymers, like PE. In this study, we address the temperature dependence in the thermo-optical properties of semi-crystalline thermoplastics concerning its effect as a thermal radiation parameter for radiation heat transfer modeling of such type of polymers. The temperature dependence in the optical properties of PE, namely transmittance and reflectance characteristics, were experimentally analyzed under heating condition and, the temperature-dependent thermo-optical properties of PE was determined. The experimental analyses showed that the change in the thermo-optical properties under heating is related to change in the optical scattering behavior in PE medium since it is strongly affected by its crystalline structure. The radiation heat transfer model was built based on optically homogeneous medium assumption at which the change in the amount of radiative energy absorbed by the PE medium under heating was introduced without modeling how the light scatters inside of the medium. Thus, the effect of optical scattering on the absorption characteristics of PE under varying temperature was taken into account without modeling the spatial distribution of the scattered light intensity at microscopic level, which offers computationally cost-effective numerical solutions. The accuracy of the numerical model was analyzed performing IR heating experiments where IR thermography and thermocouples were employed for the surface temperature measurements. Due to the semi-transparent nature of PE, an experimental method was developed for IR thermography of PE and its accuracy was analyzed. The experimental-numerical comparisons showed that the temperature field on PE can be closely predicted using its temperature-dependent thermo-optical properties. Thanks to the adopted comparative case study, it was demonstrated how the temperature field predictions may deviate from the experimental thermal measurements due to the ignorance of this temperature dependence. Considering any type of monochromatic or polychromatic radiation source, the combined experimental-numerical approach proposed here may be adopted for temperature field predictions and non-invasive surface temperature measurements on the radiatively heated semi-crystalline thermoplastics.-* Corresponding author.

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Quantification of diffuse scattering in glass and polymers by parametric power law analysis of UV to NIR light

Cited by 4 publications

References 7 publications

Hyperspectral near infrared imaging quantifies the heterogeneity of carbon materials

Hyperspectral near infrared imaging quantifies the heterogeneity of carbon materials

Cost-effective computational method for radiation heat transfer in semi-crystalline polymers

A combined experimental and numerical approach for radiation heat transfer in semi-crystalline thermoplastics

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