The processing of Pinus radiata: Pore size distribution changes in the cell wall structure studied by pressure plate technique and mercury intrusion porosimetry

Abstract

The pore size distribution of cell walls in softwood pulps was studied using the pressure plate technique and mercury intrusion porosimetry, which together make it possible to cover the range from 101 to 106 nm in pore sizes (mesopores and macropores). The differences in pore size distribution between never-dried pulp from a fiber line, industrially-dried pulp, and laboratory-dried pulps were evaluated. The results showed an increase in the relative pore volume (100 to 2,000 nm) between industrial washing and bleaching stages. Also, mercury porosimetry showed a broadening of the pore size distribution of cell walls after industrial drying. Results showed that, besides the changes in micropore and mesopore size distributions, the macropore range is also affected by processing and drying.