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Pulp is a fibrous lignocellulosic material prepared by chemically, semi-chemically or mechanically producing cellulosic fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemicals or plant-based additives, pulp is the major raw material used in papermaking and the industrial production of other paper products .
Molded pulp or molded fiber (also spelled as moulded pulp or moulded fibre) is a packaging material, that is typically made from recycled paperboard and/or newsprint. It is used for protective packaging or for food service trays and beverage carriers. Other typical uses are end caps, trays, plates, bowls and clamshell containers. [1]
The most common raw material source for fluff pulps are southern bleached softwood kraft from loblolly pine. SBSK from other species and NBSK are also used to make fluff pulp. [4] Thicker fibres are preferred to improve the bulk. Fluff pulp is normally made rolls on a drying machine (a simplified Fourdrinier machine).
The raw material is long fibered softwood fluff pulp in roll form. The pulp are defibrized in a hammermill. Defibration is the process of freeing the fibres from each other before entering the papermachine. Important parameters for dry defibration are shredding energy and knot content. Normally an air-laid paper consists of about 85% fibre.
Screening of the pulp after pulping is a process whereby the pulp is separated from large shives, knots, dirt and other debris. The accept is the pulp. The material separated from the pulp is called reject. The screening section consists of different types of sieves (screens) and centrifugal cleaning. The sieves are normally set up in a ...
Mechanical pulp can also be bleached to increase the brightness, but retaining the lignin in the pulp. [1] Industrial mechanical pulping started in the 1840s with groundwood pulping, producing the pulp from grinding. This made wood fibers the main raw material in paper, instead of textile fibers.
The raw material is normally softwood pulp from the kraft process. Maintaining a high effective sulfur ratio or sulfidity is important for the highest possible strength using the kraft process. The kraft process can use a wider range of fiber sources than most other pulping processes.
Pulp can be processed mechanically to produce tiny micro-fibrillated cellulose, which can be used to make fibres without any solvents. Pulp is dissolved in an ionic fluid, then pressed to form thin strands that can be used to make yarn; Fibres are first separated, then the material becomes a liquid and converted into textile fibres. [22]