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This research identified suitable conditions to fabricate pulp fibers for paperboards and medium density fiberboards (MDF) from the bagasse of sugarcane ( Saccharum officinarum ) and the empty fruit bunch (EFB) of oil palm ( Elaeis guineensis ). First, the effects of chemical pretreatments at 121 °C and pressurized refining under steaming conditions were studied in regards to the thermomechanical pulps. The optimal conditions to achieve the highest paper strength properties of the EFB pulp involved pretreatment with 2% NaOH for 2 h and refining at 0.7 MPa of pressure at 165 °C. The sugarcane bagasse (SB) pulp properties could not be improved by chemical pretreatment, while the EFB pulp properties clearly benefited from such pretreatment. Second, the effects of dry and wet blowing methods after pressurized refining on the fiber properties were examined. The strength properties of the half-dried SB and EFB pulps with 55% solid content were slightly higher than those of their wet counterparts. These results clearly suggest that SB and EFB can be promising refined fibers for paperboard and MDF preparation. Third, MDF was made from dried EFB refined fibers with 92% solid content by dry processing, and suitable properties for actual use were obtained.

The structural features of bast fiber and core lignins in kenaf (Hibiscus cannabinus), bark and wood lignin of paper mulberry (Broussonetia papyrifera (L.) Vent × Broussonetia kazinoki Sieb.) and mulberry (Morus bombycis) were characterized by alkaline nitrobenzene oxidation, ozonation and methoxyl group determination. Bjorkman lignins were isolated from bast fiber and core, and bark and wood fractions of the plant samples, and structural characteristics were investigated by 1H NMR and 13C NMR spectroscopies. Kenaf bast fiber gave very high molar ratio of syringaldehyde to vanillin (S/V) of alkaline nitrobenzene oxidation products, while methoxyl content was about the same as that of the core fraction. Results of 1H NMR and 13C NMR of Bjorkman lignin suggested the presence of aliphatic fragments in lignins isolated from paper mulberry and mulberry bark, but not in kenaf bast fiber. The lower yield of alkaline nitrobenzene oxidation products from bast fiber and bark might be due to the higher content of condensed structure of lignin compared to core fraction. Total yield of erythronic (E) and threonic (T) acids of ozonation products and the molar ratio of erythronic acid to threonic acid (E/T) of the bast fibers and bark were lower than the corresponding core and wood fractions, suggesting that the contents of arylglycerol-β-aryl ether intermonomer linkages in the bast fiber and bark lignin were lower than those of the core and wood fractions. Methoxyl content of bark lignin was lower than the corresponding wood lignin. The methoxyl content of the extract-free kenaf bast fiber was similar to that of the core fraction, while the values of paper mulberry and mulberry bark were about one-half of the corresponding wood fractions, respectively. In bark lignins, the methoxyl contents of Klason lignin and Bjorkman lignin from bark were lower than those of the extract-free barks. This result suggests that the purity of Klason lignin and Bjorkman lignins of bark may be rather low.

連続操業を行っている工場で国産針葉樹材パルプ収率を化学的に評価する方法について検討した。カラマツ材のKraft，Kraft―AQ，PS―AQおよびSoda―AQ蒸解の結果，キシランの再吸着などが起こるため，パルプのキシロース／グルコース比（X／G比）からパルプ収率を評価することはできないことが明らかとなった。様々なカッパー価のパルプ収率とマンノース／グルコース比（M／G比）の間では相関が低かった。Kraft，Kraft―AQおよびPS―AQ蒸解でカッパー価25のパルプでは，パルプ収率とM／G比との相関が高いことが明らかとなった。このことからアカマツ・スギ混合材を原料に用いている工場パルプのM／G比からカッパー価25のパルプ収率を評価した。Kraft法にAQを添加することで収率が1．3％増加することが示された。多変量解析により蒸解因子とヘキセンウロン酸（HexA）量の関係を示す実験式を作成した結果，AQおよびイオウの添加はHexA量を増加させる影響があることが示された。同一カッパー価，同一H―ファクターではPS―AQ蒸解が最もHexA量が高いパルプを与えた。工場実験では，Kraft―AQパルプのHexA量はKraftパルプよりも7μmol／g高い値となった。

Hibiscus cannabinus (kenaf) plants grown in the Agricultural and Forestry Research Center at the University of Tsukuba were separated into three parts, (upper, middle and lower), and their bast and core parts were subjected to protein, lignin and carbohydrates analyses. We clarified the differences of the chemical features of these parts. The lower part of the core contained more lignin and xylan than the upper part and the upper and lower bast parts. The core accumulated a large amount of lignin with a high syringyl to guaiacyl ratio, which suggests rich non-condensed lignin structures. Cooking efficiency of the bast was compared with that of Acacia mearnsii, Eucalyptus spp. and Cryptomeria japonica wood under kraft-anthraquinone pulping conditions. Although the lignin content of the bast was lower than that of A. mearnsii wood, the selectivity of delignification of the bast was not better than that of the hardwood in the kraft pulping process. However, the bast pulp was easily oxygen-bleached, resulting in a low kappa number.