Chemical Composition, Fiber Morphology, and Kraft Pulping of Bracken Stalks (Pteridium aquilinum (L.) Kuhn) Kemijski sastav, morfologija vlakana i sulfatni postupak proizvodnje celuloze od stabljika paprati (Pteridium aquilinum (L.) Kuhn)Original scientifi c paper • Izvorni znanstveni rad ABSTRACT • In this study, kraft, kraft-NaBH 4 , and kraft-KBH 4 pulp and paper properties of the bracken stalks (Pteridium aquilinum (L.) Kuhn) were determined. Also, the chemical composition and fi ber properties of bracken stalks were evaluated. NaBH 4 and KBH 4 were separately added to cooking liquor by 0.5 %, 1 %, 1.5 %, and 2 % (oven dried wood). The boron compound-free kraft pulp were also made as control pulp. Fiber length and fi ber width of bracken stalks were determined as 1.25 mm and 24 μm, respectively. Bracken stalks are composed of 73.34 % holocellulose, 32.55 % α-cellulose, and 30.79 % lignin. In addition, the pulp yield was increased with additions of both boron compounds, while kappa number was decreased. Also, highest strength increases determined in 0.5 % NaBH 4 added pulp. These results showed that bracken stalks can be used as a raw material for kraft pulp production. SAŽETAK • U radu su opisana istraživanja svojstava kraft, kraft-NaBH 4 i kraft-KBH 4 celuloze i papira proizvedenih od stabljika paprati (Pteridium aquilinum (L.) Kuhn). Ocijenjeni su kemijski sastav i svojstva vlakana stabljika paprati. Otopini za kuhanje odvojeno su dodavani NaBH 4 i KBH 4 u postotcima 0,5; 1; 1,5 i 2 % (u odnosu prema apsolutno suhom drvu). Kraft celuloza bez spojeva bora proizvedena je kao kontrolni uzorak. Duljina vlakana stabljika paprati iznosila je 1,25 mm, a širina 24 μm. Stabljike paprati sadržavaju 73,34 % holoceluloze, 32,55 % α-celuloze i 30,79 % lignina. Rezultati su pokazali da je uz dodatak obaju spojeva bora prinos celuloze povećan, dok je Kapa broj smanjen. Usto, rezultati su pokazali najveće povećanje čvrstoće za celulozu dobivenu dodatkom 0,5 % NaBH 4 . Na temelju dobivenih rezultata može se zaključiti da se stabljike paprati mogu upotrebljavati kao sirovina za proizvodnju kraft celuloze.Ključne riječi: paprat, KBH 4 , sulfatni postupak, NaBH 4 , Pteridium aquilinum (L.) Kuhn., svojstva papira 1 Authors are associated professor and M.Sc. at

In this study, the effects of potassium borohydride (KBH 4 ) on maritime pine (Pinus pinaster Ait.) kraft pulp and paper properties were investigated. 0.5%, 1%, 1.5%, and 2% (based on oven-dried wood) KBH 4 added kraft cookings were carried out under the fixed cooking conditions. KBH 4 -free kraft cooking was also done as control cooking. The results revealed that pulp yield, kappa number, and beating time increased with addition of KBH 4 to cooking liquor. The screened yield increased 7.69 point (from 46,21% to 53.90%) with 2% KBH 4 addition to control cooking. The brightness values of handsheets were increased with KBH 4 addition. Strength properties of handsheets significantly decreased with addition of KBH 4 .