2024-03-29T07:43:21Z
https://niigata-u.repo.nii.ac.jp/oai
oai:niigata-u.repo.nii.ac.jp:00001697
2022-12-15T03:34:28Z
453:454
485:486:487
Photoyellowing of chemically modified chemithermomechanical pulps (CTMP) from Eucalyptus globulus under various atmospheres
Photoyellowing of chemically modified chemithermomechanical pulps (CTMP) from Eucalyptus globulus under various atmospheres
Kojima, Yasuo
5076
Kato, Yoshiaki
5077
Ishikura, Yukiko
5078
Yoon, Seung-Lak
5079
Ona, Toshihiro
5080
chemical modification of CTMP
CTMP
Eucalyptus
oxygen
photoyellowing
UV microspectrophotometer(UMSP)
Chemithermomechanical pulps (CTMP) were prepared from Eucalyptus globulus and photoirradiated, and the responses have been examined by means of ultraviolet (UV) microspectrophotometer. The absorbance in the UV spectra of fiber walls increased in the range of 300 of 350 nm as a result of photoirradiation, indicating the formation of conjugated double-bound systems in the fiber walls. These spectral changes occurred only on the irradiated surface of sheets. CTMP photoirradiation under various atmospheres indicated that the presence of oxygen in the irradiation atmosphere is not necessary for CTMP yellowing. In nitrogen or vacuum, photoyellowing was at the same level as observed under oxygen. This observation was interpreted as a result of direct elimination of proton radicals from free phenolic groups and/or cleavage of β-aryl ether linkages. This induced probably the excited triplet state of α-carbonyl structures in CTMP, which leads to chromophore formation in the absence of oxygen. Reduction of CTMP with sodium borohydride impeded effectively the effects of photoirradiation only in the absence of oxygen. On the contrary, acetylation of CTMP had no effect in the absence of oxygen but led to photobleaching in the presence of oxygen.
journal article
Walter de Gruyter
2014-01
application/pdf
Holzforschung
2
68
143
149
Holzforschung
AA00664822
00183830
https://niigata-u.repo.nii.ac.jp/record/1697/files/68_2_143-149.pdf
eng
info:doi/10.1515/hf-2013-0086