According to its refining degree, it can be divided into three kinds: unbleached, semi-bleached and bleached. Unbleached pulp contains a small amount of lignin and colored impurities, so it is yellow and the fiber is hard.

Only the heartwood and sapwood are useful for making pulp. Bark contains relatively few useful fibers and is removed and used as fuel to provide steam for use in the pulp mill. Most pulping processes require that the wood be chipped and screened to provide uniform sized chips.

Explanation: Following are the four broad categories of pulping: Chemical, semi-chemical, chemi-mechanical, and mechanical. These are in increasing order of mechanical energy required to separate fibers and decreasing reliance on chemical action. 3.

Nonwood fibers, also referred to as ”alternate fibers”, are nonwoody cellulosic plant materials from which papermaking fibers can be extracted. The most widely used nonwoods for papermak- ing are straws, sugar cane bagasse, bamboo, kenaf, hemp, jute, sisal, abaca, cotton linters, and reeds.

Extended Delignification Chemical pulping and bleaching of chemical pulps are both delignification reactions. Of course, bleaching reactions are much more specific for lignin removal than pulping but are much more expensive.

Chemical wood pulping involves the extraction of cellulose from wood by dissolving the lignin that binds the cellulose fibers together. The 4 processes principally used in chemical pulping are kraft, sulfite, neutral sulfite semichemical (NSSC), and soda.

Put simply, wood pulp is a lignocellulosic fibrous material that is produced by separating cellulose fibers from wood, fiber crops or waste paper. Unsurprisingly, pulp is regularly used as the source material in paper products. You can find this ingredient in everything from newspapers to toilet paper.

Paper is made from softwood or hardwood trees, but 85% of the wood pulp that makes paper in the U.S. comes from softwood coniferous trees. They have longer fibers known to produce stronger paper. The primary trees in this category are pines, firs, spruces, hemlocks, and larch.

Wood pulp is a versatile material used for a wide variety of products. “We can consider four main end uses for wood pulp. They are tissue, printing and writing papers, board and specialty papers.

What is Pulp? Pulp is made from breaking down the fibrous part of plants, primarily trees or recycled paper, and refers to the main ingredient in the papermaking process. Pulp made from trees (wood fiber) is the most common source of fiber for papermaking and the base for many paper and wood products.

Soda pulping, invented in England by Burgess and Watts in 1851, uses sodium hydroxide as the cooking chemical. Finding little enthusiasm in England for this new process, Burgess brought the method to the United States in 1854, and the first mill was started in 1866.

We make kraft pulp by mixing wood fibres with a solution of caustic soda and sodium sulphide, and cooking them inside a digester. This separates the fibres from the lignin, which is a natural glue-like substance that binds them together.

Nowadays, in the total pulp consumption of the world, the proportions of wood pulp, wastepaper pulp, and non-wood pulp are 63, 34, and 3%, respectively. The bamboo, and bagasse, would play a major role in optimizing papermaking raw materials.

This kind of raw materials include bamboo, bagasse, rice straw, is generally around 50%, closing to wood. However, with the heterogeneity of cellulose, the utilization of this kind of plant in pulping is far less than that of wood. 2.2. Bast ber materials

However, due to shortage of wood resources, utilization of non-wood fibers remains important in China. The total production capacity of bamboo pulp in China reached 2,400,000 tons in 2017, and most of the bamboo pulps (about 80%) are for the production of household paper grades.

” Bamboo as an emerging resource for worldwide pulping and papermaking ,” BioRes. 14 (1), 3-5. As a widely distributed and fast growing graminaceous plant, bamboo has emerged as an important raw material for pulping and papermaking to mitigate the shortage of wood resources, at least in the East Asia region.