Effect of Cellulases and Xylanases on Refining Process and Kraft Pulp Properties.

Samples of bleached kraft pine cellulosic pulp, either treated with an enzyme preparation (a Thermomyces lanuginosus xylanase, an Aspergillus sp. cellulase, and a multienzyme preparation NS-22086 containing both these activities) or untreated, were refined in a laboratory PFI mill. The treatment with cellulases contained in the last two preparations significantly improved the pulp's susceptibility to refining (the target freeness value of 30°SR was achieved in a significantly shorter time), increased water retention value (WRV) and fines contents while the weighted average fiber length was significantly reduced. These changes of pulp parameters caused deterioration of paper strength properties. The treatment with the xylanase, which partially hydrolyzed xylan, small amounts of which are associated with cellulose fibers, only slightly loosened the structure of fibers. These subtle changes positively affected the susceptibility of the pulp to refining (refining energy was significantly reduced) and improved the static strength properties of paper. Thus, the treatment of kraft pulps with xylanases may lead to substantial savings of refining energy without negative effects on paper characteristics

Data from: Effect of cellulases and xylanases on refining process and kraft pulp properties

Samples of bleached kraft pine cellulosic pulp, either treated with an enzyme preparation (a Thermomyces lanuginosus xylanase, an Aspergillus sp. cellulase, and a multienzyme preparation NS-22086 containing both these activities) or untreated, were refined in a laboratory PFI mill. The treatment with cellulases contained in the last two preparations significantly improved the pulp’s susceptibility to refining (the target freeness value of 30°SR was achieved in a significantly shorter time), increased water retention value (WRV) and fines contents while the weighted average fiber length was significantly reduced. These changes of pulp parameters caused deterioration of paper strength properties. The treatment with the xylanase, which partially hydrolyzed xylan, small amounts of which are associated with cellulose fibers, only slightly loosened the structure of fibers. These subtle changes positively affected the susceptibility of the pulp to refining (refining energy was significantly reduced) and improved the static strength properties of paper. Thus, the treatment of kraft pulps with xylanases may lead to substantial savings of refining energy without negative effects on paper characteristics

Structural, morphological and photoluminescent properties of annealed ZnO thin layers obtained by the rapid sol-gel spin-coating method

ZnO thin layers were deposited on p-type silicon substrates by the sol-gel spin-coating method and, then, annealed at various temperatures in the range of 573-873 K. Photoluminescence was carried out in the temperature range of 20-300 K. All samples showed two dominant peaks that have UV emissions from 300 nm to 400 nm and visible emissions from 400 nm to 800 nm. Influence of temperature on morphology and chemical composition of fabricated thin layers was examined by XRD, SEM, FTIR, and Raman spectroscopy. These measurements indicate that ZnO structure is obtained for samples annealed at temperatures above 573 K. It means that below this temperature, the obtained thin films are not pure zinc oxide. Thus, annealing temperature significantly affected crystallinity of the thin films

The effect of enzymatic pulp treatment on the number of PFI mill revolutions required to achieve the freeness of 30°SR.

<p>The effect of enzymatic pulp treatment on the number of PFI mill revolutions required to achieve the freeness of 30°SR.</p

The effect of enzyme preparations and number of PFI mill revolutions on the weighted average fiber length.

<p>The effect of enzyme preparations and number of PFI mill revolutions on the weighted average fiber length.</p

Effects of enzyme treatment and PFI revolutions number on pulp freeness (a), water retention value (b) and fines content (c).

<p>Effects of enzyme treatment and PFI revolutions number on pulp freeness (a), water retention value (b) and fines content (c).</p

The impact of the dose of enzymatic preparation and pretreatment time on the selected pulp and paper properties.

<p>The impact of the dose of enzymatic preparation and pretreatment time on the selected pulp and paper properties.</p

The dependence of tear resistance: breaking length ratio on enzymatic pulp treatment.

<p>The dependence of tear resistance: breaking length ratio on enzymatic pulp treatment.</p