| 1. |
- Lundström-Hämälä, Lisa, et al.
(författare)
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The adsorption of polyelectrolyte multilayers (PEM) of starch on mechanical pulps for improved mechanical paper properties
- 2009
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 24:4, s. 459-468
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, the long fibre and middle fibre fraction of a thermomechanical pulp (TMP) was treated with polyelectrolyte multilayers (PEMs) of cationic and anionic starch and sheets were made from both the treated and untreated fractions. In separate experiments, different amounts of untreated fines were added to the PEM-treated fraction before sheets were prepared, and the results were also compared with PEM treatment of the entire pulp containing 17% fines before sheet preparation. The PEMs were made of two different combinations of starch, two cationic potato starches with DS values of 0.06 and 0.09, both in combination with an anionic potato starch with a DS of 0.04, at 0.010 M NaCl and pH 6.3. Sheets were formed using the Rapid Kothen sheet former and the resulting mechanical and optical sheet properties were evaluated. Four-layer PEM treatment of the long fibre and middle fraction resulted in significant improvements in in-plane and out-of-plane mechanical properties. However, a subsequent fines addition reduced the effect of the PEMs, and this is explained by a blocking of the necessary PEM interaction with the treated TMP long fibre and middle fraction by the subsequently added fines. PEM treatment of the entire pulp increased the amount of starch needed for PEM treatment, but improved the in-plane and out-of-plane mechanical properties compared with those of sheets prepared from a PEM-treated long fibre and middle fraction with a subsequent addition of fine material. The increase in the tensile index for sheets made from a PEM-treated long fibre and the middle fraction without a subsequent fines addition, however, was much larger.
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| 2. |
- Niklasson, Annika, 1977, et al.
(författare)
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Air Pollutant Concentrations and Atmospheric Corrosion of Organ Pipes in European Church Environments
- 2008
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Ingår i: Studies in Conservation. - 0039-3630 .- 2047-0584. ; 53:1, s. 24-40
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: The atmospheric environment inside and outside historical organs in several European regions is reported. In each region, comparisons were made between an instrument suffering organ pipe corrosion and an organ without corrosion problems. Concentrations of acetic acid (ethanoic acid), formic acid (methanoic acid), acetaldehyde (ethanal), formaldehyde (methanal) and other volatile organic compounds in the organ environment were determined using active sampling. Temperature and relative humidity were recorded. In addition, polished metal samples that mimic the material used in the historical organ pipes have been exposed in the organ wind systems for up to 22 months. High concentrations of acetic acid and formic acid vapours are present in the wind system of the corroded organs. Acetaldehyde and formaldehyde are also present in smaller amounts. The main source of acetic acid is the wood from which the wind system is built. In contrast, formic acid is generated in the chruch environment outside the wind system. The results show that the two organic acids play an important role in the atmospheric corrosion of organ pipes. It is suggested that the corrosion of lead pipes in historical organs can be effectively reduced by removing the sources of gaseous acetic acid and formic acid in the wind system and in the chruch environment.
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