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Wood-free paper is paper created exclusively from chemical pulp rather than mechanical pulp. [1] Chemical pulp is normally made from pulpwood, but is not considered wood as most of the lignin is removed and separated from the cellulose fibers during processing, whereas mechanical pulp retains most of its wood components and can therefore still be described as wood. [2] [3] [4] Wood-free paper is not as susceptible to yellowing as paper containing mechanical pulp. Wood-free paper offers several environmental and economic benefits, including reduced deforestation, decreased energy consumption, and improved waste management. [5] [6] The term Wood-free paper can be rather misleading or confusing for someone unfamiliar with the papermaking process because paper is normally made from wood pulp derived from trees and shrubs. However, wood free paper does not mean that the paper in question is not made from wood pulp but it means that the lignin in the wood fiber has been removed by a chemical process.
Paradoxically, lignin is the complex polymers containing aromatic groups that provide much of the tree strength. In its natural form, it gives rigidity and resilience to the tree, but its presence causes paper to weaken and turn yellow as it ages and eventually disintegrate.
The reason for this is that as the paper ages, lignin releases acid which degrades the paper. [7]
Wood is technically a lignocellulosic material and a xylem tissue that comes from shrubs and cambium, the inner bark of trees made up of extractives, lignin, hemicellulose and cellulose. [8]
Pulp consists of wood and other lignocellulosic materials that have been broken down chemically and physically and filtered and mixed in water to reform into a web. [9] [10] Creating pulp by breaking down the materials chemically is called chemical pulping, while creating pulp by breaking them down mechanically is called mechanical pulping.
In chemical pulping, chemicals separate the wood fibers. The chemicals lower the lignin content because chemical action solubilizes and degrades components of wood fibers, especially hemicelluloses and lignin.
Chemical pulping yields single unbroken fibers that produce strong quality papers because the lignin that interferes with hydrogen bonding of wood fibers has been removed. Chemical pulps are used to create wood free paper that is of high quality and lasts long, such as is used in arts and archiving [11]
Chemical pulping processes take place at high pressures and temperatures under aqueous alkaline, neutral or acidic conditions, with the goal of totally removing the lignin and preserving the carbohydrates. Normally, about 90% of the lignin is removed. [12]
Mechanical pulping, in contrast, converts raw wood into pulp without separating the lignin from the wood fiber. [13] No chemicals other than water or steam are used. The yield is about 90% to 98%. High yields result from the fact that lignin is retained.
Mechanical pulps are characterized by low cost, high stiffness, high bulk, and high yield. Mechanical pulp has low strength because the lignin interferes with hydrogen bonding between wood fibers.
The lignin also makes the pulp turn yellow when exposed to light and air.
Mechanical pulps are used in the production of non-permanent papers such as newsprint and catalog papers.
Mechanical pulps made up 20% to 25% of the world production and this is increasing because of the high yield of the process and increasing competition for fiber resources.
Advances in technology have also made mechanical pulp increasingly desirable. [14]
Wood-free paper is made from a variety of raw materials, including
Wood-free paper has a number of advantages over paper that contains mechanical pulp:
Wood-free paper is used in a variety of applications:
Non-wood paper, commonly referred to as tree-free paper or wood-free paper, is essential for encouraging sustainability and minimizing deforestation. [40] Wood-free paper offers substantial environmental advantages over conventional wood pulp since it uses alternative fibers and ingredients. [41] The use of wood-free paper is instrumental in promoting sustainability and reducing deforestation for several key reasons: [42]
Wood-free paper is made from non-wood materials, such as cotton, hemp, linen, and bamboo. [56] [57] [58] It is often used in applications where a high-quality, durable paper is needed, such as for printing, writing, and packaging.
There are two main types of wood-free paper:
Tissue pulp paper is smooth and opaque, making it ideal for printing and writing. [61] [62] [63] It is also relatively inexpensive, making it a popular choice for many applications. Non-wood pulp paper is more expensive than tissue pulp paper, but it is also more durable and has a higher quality. [64] [65] [66] It is often used for high-end printing and writing applications, as well as for packaging.
Here are some of the specific types of wood-free papers:
Wood-free paper is a good choice for applications where a high-quality, durable paper is needed. [70] It is also a sustainable choice, as it is made from renewable and recyclable materials.
Wood-free papers come in two varieties: uncoated and coated. Uncoated is typically used for printing and writing but also used in some packaging applications, whereas coated is used for things such as packaging and labels. [71]
Agricultural residues refer to the organic materials that are left over after crops are harvested. [80] [81] These residues include the stems, leaves, husks, and other parts of plants that are not used for food or other primary products. [82] [83] They are a significant component of agricultural ecosystems and have various potential uses, both beneficial and detrimental. [84] [85] [86] Here's a detailed overview of agricultural residues:
Cotton is a natural fiber that has been used for thousands of years to make textiles. It is derived from the fibers surrounding the seeds of the cotton plant (Gossypium). [127] [128] Here's a detailed overview of cotton:
Hemp, scientifically known as Cannabis sativa, is a versatile plant that has been cultivated for thousands of years for various purposes, including fiber, food, medicine, and industrial applications. Here's a detailed overview of hemp:
Cellulose is an organic compound with the formula (C
6H
10O
5)
n, a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the most abundant organic polymer on Earth. The cellulose content of cotton fiber is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%.
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by cross-linking phenolic precursors.
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw material used in papermaking and the industrial production of other paper products.
The pyrolysis process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere.
Lyocell is a semi-synthetic fiber used to make textiles for clothing and other purposes. It is a form of regenerated cellulose made by dissolving pulp and dry jet-wet spinning. Unlike rayon made by some of the more common viscose processes, Lyocell production does not use carbon disulfide, which is toxic to workers and the environment. Lyocell was originally trademarked as Tencel in 1982.
Fiber crops are field crops grown for their fibers, which are traditionally used to make paper, cloth, or rope.
Bagasse is the dry pulpy fibrous material that remains after crushing sugarcane or sorghum stalks to extract their juice. It is used as a biofuel for the production of heat, energy, and electricity, and in the manufacture of pulp and building materials. Agave bagasse is similar, but is the material remnants after extracting blue agave sap.
Hemp, or industrial hemp, is a plant in the botanical class of Cannabis sativa cultivars grown specifically for industrial and consumable use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest growing plants on Earth. It was also one of the first plants to be spun into usable fiber 50,000 years ago. It can be refined into a variety of commercial items, including paper, rope, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed.
The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper. In some situations, the process has been controversial because kraft plants can release odorous products and in some situations produce substantial liquid wastes.
Banana paper is a type of paper created from banana plant bark or banana peel fibers. Banana paper has a lower density, higher stiffness, higher disposability, higher renewability, and higher tensile strength compared to traditional paper. These qualities are due to the cellular composition of banana fiber, which consists of cellulose, hemicellulose, and lignin.
Cellulosic ethanol is ethanol produced from cellulose rather than from the plant's seeds or fruit. It can be produced from grasses, wood, algae, or other plants. It is generally discussed for use as a biofuel. The carbon dioxide that plants absorb as they grow offsets some of the carbon dioxide emitted when ethanol made from them is burned, so cellulosic ethanol fuel has the potential to have a lower carbon footprint than fossil fuels.
A biorefinery is a refinery that converts biomass to energy and other beneficial byproducts. The International Energy Agency Bioenergy Task 42 defined biorefining as "the sustainable processing of biomass into a spectrum of bio-based products and bioenergy ". As refineries, biorefineries can provide multiple chemicals by fractioning an initial raw material (biomass) into multiple intermediates that can be further converted into value-added products. Each refining phase is also referred to as a "cascading phase". The use of biomass as feedstock can provide a benefit by reducing the impacts on the environment, as lower pollutants emissions and reduction in the emissions of hazard products. In addition, biorefineries are intended to achieve the following goals:
A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or fully chemical methods. The finished product may be either bleached or non-bleached, depending on the customer requirements.
Lignocellulose refers to plant dry matter (biomass), so called lignocellulosic biomass. It is the most abundantly available raw material on the Earth for the production of biofuels. It is composed of two kinds of carbohydrate polymers, cellulose and hemicellulose, and an aromatic-rich polymer called lignin. Any biomass rich in cellulose, hemicelluloses, and lignin are commonly referred to as lignocellulosic biomass. Each component has a distinct chemical behavior. Being a composite of three very different components makes the processing of lignocellulose challenging. The evolved resistance to degradation or even separation is referred to as recalcitrance. Overcoming this recalcitrance to produce useful, high value products requires a combination of heat, chemicals, enzymes, and microorganisms. These carbohydrate-containing polymers contain different sugar monomers and they are covalently bound to lignin.
A biocomposite is a composite material formed by a matrix (resin) and a reinforcement of natural fibers. Environmental concern and cost of synthetic fibres have led the foundation of using natural fibre as reinforcement in polymeric composites. The matrix phase is formed by polymers derived from renewable and nonrenewable resources. The matrix is important to protect the fibers from environmental degradation and mechanical damage, to hold the fibers together and to transfer the loads on it. In addition, biofibers are the principal components of biocomposites, which are derived from biological origins, for example fibers from crops, recycled wood, waste paper, crop processing byproducts or regenerated cellulose fiber (viscose/rayon). The interest in biocomposites is rapidly growing in terms of industrial applications and fundamental research, due to its great benefits. Biocomposites can be used alone, or as a complement to standard materials, such as carbon fiber. Advocates of biocomposites state that use of these materials improve health and safety in their production, are lighter in weight, have a visual appeal similar to that of wood, and are environmentally superior.
Agricultural waste are plant residues from agriculture. These waste streams originate from arable land and horticulture. Agricultural waste are all parts of crops that are not used for human or animal food. Crop residues consist mainly of stems, branchs, and leaves. It is estimated that, on average, 80% of the plant of such crops consists of agricultural waste.
Tree-free paper, or tree-free newsprint, is described as an alternative to wood-pulp paper due to its raw material composition. It is claimed to be more eco-friendly when considering the product's entire life cycle.
Cellulose fibers are fibers made with ethers or esters of cellulose, which can be obtained from the bark, wood or leaves of plants, or from other plant-based material. In addition to cellulose, the fibers may also contain hemicellulose and lignin, with different percentages of these components altering the mechanical properties of the fibers.
Cotton recycling is the process of converting cotton fabric into fibers that can be reused into other textile products.
Hemp paper is paper varieties consisting exclusively or to a large extent from pulp obtained from fibers of industrial hemp. The products are mainly specialty papers such as cigarette paper, banknotes and technical filter papers. Compared to wood pulp, hemp pulp offers a four to five times longer fibre, a significantly lower lignin fraction as well as a higher tear resistance and tensile strength. Because the paper industry's processes have been optimized for wood as the feedstock, production costs currently are much higher than for paper from wood.
There are two main types of woodfree paper: uncoated and coated. Uncoated woodfree paper is typically used for printing and writing. It is also used in some packaging applications. Coated woodfree paper is used for packaging, labels, and other applications where a more durable paper is needed.
[Woodfree paper] is also less likely to warp or curl.