- 标题
- 摘要
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- 实验方案
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Modeling of Radiative Properties of Polystyrene Foams Containing IR-Opacifiers
摘要： The addition of opacifiers in foams considerably reduces the radiative thermal conductivity and consequently enhances the insulation performance of the foams. In this work two different methods were developed to calculate the spectral specific extinction coefficient of opacified extruded polystyrene (XPS) foam material. Cell morphology and thermal conductivity of two identical XPS-foams, one opacified with 3 wt% carbon black as opacifier and one without opacifier, were thoroughly characterized. The experimental results were in a good agreement with the theoretical results obtained from two different computing techniques. These methods allow a good prediction of the specific extinction coefficient of arbitrary opacified foam material.
关键词： Radiative transfer,Radiative thermal conductivity,Complex refractive index,Extinction coefficient,Porous materials,Opacifiers
更新于2025-09-23 15:23:52
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Spherical particle absorption over a broad range of imaginary refractive index
摘要： This paper presents studies of the optical absorption cross section for homogeneous spheres of radius R interacting with light of wavelength λ as calculated with the Mie equations. Four regimes of behavior are disclosed: the Rayleigh Regime, the Geometric Regime, the Re?ection Regime, and a Crossover Regime. Two parameters govern these regimes, the imaginary part of the refractive index, κ, and the product of κ with the sphere size parameter kR where k = 2 π / λ, i.e. κkR . Simple, approximate functionalities on κ, k , sphere volume and projected geometric cross section are derived for these regimes. Interesting aspects of our observations include: Rayleigh absorption can apply to all particle sizes, Fresnel re?ection can occur for sub-wavelength spheres, and while κ is the agent of absorption, large κ can increase scattering to the detriment of absorption.
关键词： Absorption,Complex refractive index,Rayleigh theory,Mie theory
更新于2025-09-19 17:15:36
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Determination of complex refractive index of SU-8 by Kramers-Kronig dispersion relation method at the wavelength range 2.5 – 22.0 μm
摘要： Accurate determination of the complex refractive index of SU-8 epoxy has significant for the wide variety of applications in optical sensor technology at IR range. The complex refractive index of SU-8 is determined by recording the transmission of light spectra for the wavelength range of 2.5 – 22.0 μm. The data analysis is based on the Kramers-Kronig dispersion relation method. The method has several merits, such as ease of operation, non-contact technique, measurement accuracy, and rapid measurement. The present method is not restricted to the case of SU-8 but it is also proposed to be applicable across a broad range of applications, such as assessment of the optical properties of paints and biomedical samples.
关键词： SU-8 epoxy,FT-IR spectrophotometer,Infrared region,Kramers-Kronig dispersion relation method,Complex refractive index
更新于2025-09-10 09:29:36