Effectiveness of principal component analysis for analyzing particleboard subjected to outdoor exposure

Abstract

In order to investigate the strength reduction of particleboards subjected to outdoor exposure at eight sites across Japan, the climate factors, i.e., temperature, sunshine duration, and precipitation were analyzed using a principal component analysis. The first principal component (PC1) had an eigenvalue of 2.31 and a proportion of 76.9 %, indicating that the PC1 combines the climate factors into one factor. All of the PC1 eigenvectors demonstrated high, positive values for each climate factor, demonstrating that the first principal component score (PC1 score) increases with increasing temperature, sunshine duration, and precipitation. The PC1 score was introduced as a new index for evaluating strength reduction, as the strength shows a strong correlation with the PC1 score: a higher PC1 score was linked to lower particleboard strength after the outdoor exposure test. The PC1 score can be calculated directly and unambiguously using the climate factors; further, the PC1 score was found to be a more powerful index than each individual climate factors or a combination of them.