A Comparative Study of NIR Diffuse Reflectance of Cottons Grouped According to Fiber Cross-Sectional Dimensions. Part II: Optical Path Simulations

Abstract

In Part I of this series, a model was proposed to predict the comparative NIR reflectance of cottons grouped according to cross-sectional dimensions. The critical assumption in the model is that total fiber length in the diffuse reflectance optical path is constant among cottons of the same perimeter. This paper introduces an alternative assumption: that the volume of solid cellulose (i.e., mass) in the diffuse reflectance optical path is constant for cottons of the same perimeter. Optical path simulations are used to predict the consequences of either assumption. One method of simulation is based on diffuse reflectance calculations and the other on relating diffuse reflectance to diffuse transmittance. In the diffuse reflectance calculations, 13 variables are included in the simulation model. Relating reflectance to transmittance is justified because sample weights for the latter can be selected a priori to produce either a constant total fiber length or a constant volume of solid cellulose in the optical path. The simulations support the premise that the critical assumption in the comparative reflectance model is correct. The study goes further to produce diagnostic criteria from the simulation results for testing the assumptions.