Rapid determination of biomass and polypropylene in three types of wood plastic composites (WPCs) using FTIR spectroscopy and partial least squares regression (PLSR)

Abstract

Abstract The biomass/plastic ratio in wood plastic composites (WPCs) has been evaluated because of the great practical importance of this topic. To this purpose, FTIR spectra of 59 polypropylene (PP)-based WPCs from three biomass species (Chinese fir, poplar, and bamboo) were recorded and the spectral dates were evaluated by means of the partial least squares regression (PLSR) approach aiming at the prediction of the biomass/PP ratio in the WPCs. The results of the full cross-validation of the data showed that first derivative spectra corrected by standard normal variate (SNV) yielded the optimal model for prediction of the WPC composition. For both biomass and PP prediction, the coefficients of determination (R 2) of external validation were above 0.94. The standard errors of prediction (SEP) were between 1.38 and 1.39. And the ratios of performance to deviation (RPD) were about 4.20. The relative prediction errors in this context were lower than ±6%. FTIR combined with PLSR is a useful tool for a rapid and reliable estimation of the biomass and PP contents in different types of PP-based WPCs.