What is the whiteness of pulp? How to test whiteness?
Release time:
2024-01-30 10:22
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The whiteness of pulp is measured using its ability to reflect monochromatic light in comparison to a known standard whiteness (usually magnesium oxide). The most commonly used instrument is the Zeiss Elrepho reflectometer, which emits a scattered light source. The whiteness measured for fully bleached sulphite pulp can be as high as 94 Elrepho units, while unbleached sulphite pulp can be as low as 15 Elrepho units.
Unbleached pulp shows a wide range of whiteness values. The sulphite method produces pulp with a fairly high whiteness (up to 65), while those produced by the sulphate, caustic soda and semi-chemical pulp methods can be very low. The whiteness of mechanical pulp is mainly related to the species and condition of the wood used for pulping. In general, only those wood species with whiteness values above 55 are used for mechanical pulping.
Cellulose and hemicellulose are naturally white and have no effect on pulp colour. Chromophores in the structure of lignin are generally considered to be the main cause of pulp colour; the mechanism is claimed to be the partial oxidation of the phenol group of lignin to a benzoquinone-type substance, which is known to absorb coloured light. It has also been known that heavy metal ions (e.g. iron and copper) form coloured complexes with the phenol group. The extractives may affect the colour of mechanical pulp made from fat-containing wood.
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What is the whiteness of pulp? How to test whiteness?
The whiteness of pulp is measured using its ability to reflect monochromatic light in comparison to a known standard whiteness (usually magnesium oxide). The most commonly used instrument is the Zeiss Elrepho reflectometer, which emits a scattered light source. The whiteness measured for fully bleached sulphite pulp can be as high as 94 Elrepho units, while unbleached sulphite pulp can be as low as 15 Elrepho units.
What is the whiteness of pulp? How to test whiteness?
The whiteness of pulp is measured using its ability to reflect monochromatic light in comparison to a known standard whiteness (usually magnesium oxide). The most commonly used instrument is the Zeiss Elrepho reflectometer, which emits a scattered light source. The whiteness measured for fully bleached sulphite pulp can be as high as 94 Elrepho units, while unbleached sulphite pulp can be as low as 15 Elrepho units.
What is the whiteness of pulp? How to test whiteness?
The whiteness of pulp is measured using its ability to reflect monochromatic light in comparison to a known standard whiteness (usually magnesium oxide). The most commonly used instrument is the Zeiss Elrepho reflectometer, which emits a scattered light source. The whiteness measured for fully bleached sulphite pulp can be as high as 94 Elrepho units, while unbleached sulphite pulp can be as low as 15 Elrepho units.
What is the whiteness of pulp? How to test whiteness?
The whiteness of pulp is measured using its ability to reflect monochromatic light in comparison to a known standard whiteness (usually magnesium oxide). The most commonly used instrument is the Zeiss Elrepho reflectometer, which emits a scattered light source. The whiteness measured for fully bleached sulphite pulp can be as high as 94 Elrepho units, while unbleached sulphite pulp can be as low as 15 Elrepho units.
What is the whiteness of pulp? How to test whiteness?
The whiteness of pulp is measured using its ability to reflect monochromatic light in comparison to a known standard whiteness (usually magnesium oxide). The most commonly used instrument is the Zeiss Elrepho reflectometer, which emits a scattered light source. The whiteness measured for fully bleached sulphite pulp can be as high as 94 Elrepho units, while unbleached sulphite pulp can be as low as 15 Elrepho units.
What is the whiteness of pulp? How to test whiteness?
The whiteness of pulp is measured using its ability to reflect monochromatic light in comparison to a known standard whiteness (usually magnesium oxide). The most commonly used instrument is the Zeiss Elrepho reflectometer, which emits a scattered light source. The whiteness measured for fully bleached sulphite pulp can be as high as 94 Elrepho units, while unbleached sulphite pulp can be as low as 15 Elrepho units.
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