Pinus radiata chips were pulped on a laboratory scale to yields betwee
n 47% and 96%. A ''delayed contact'' pulse sequence was used to separa
te C-13 CP/MAS NMR spectra into subspectra of pulp components. Results
showed a smooth increase in the degree of crystallinity of the intact
cellulose fibrils from 0.53 for the high-yield pulps to a plateau at
about 0.60 for low-yield pulps. This was interpreted in terms of prefe
rential loss of disordered cellulose in the early stages of pulping. C
ellulose damage was observed for pulp yields below 57%. with a maximum
of 16% of total cellulose being physically damaged at 47% pulp yield.
A combination of chemical analysis and NMR spectra provided evidence
for molecular ordering in about half of the residual hemicelluloses. N
MR estimates of residual lignin contents were in good agreement with K
lason lignin values.