Wood-free paper

Not to be confused with Tree-free paper.

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.^[8][9] 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.^[8] 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.^[9]

Mechanical pulping, in contrast, converts raw wood into pulp without separating the lignin from the wood fiber.^[9] 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.^[8]

Composition

Wood-free paper is made from a variety of raw materials, including

• Tissue pulp: This is the most common type of wood-free paper. It is made from wood pulp that has been treated with chemicals to remove the lignin.^{[10][11][12][13]}
• Balsa pulp: This is a type of wood pulp that is made from balsa trees. It is very strong and lightweight, making it ideal for use in envelopes and other lightweight applications.^[14][15]
• Coniferous pulp: This is a type of wood pulp that is made from coniferous trees, such as pine and fir. It is strong and durable, making it ideal for use in writing and printing papers.^{[16][17][18][19]}
• Non-wood pulp: This is a type of pulp that is made from non-wood materials, such as cotton, hemp, and linen. It is often used in high-quality papers, such as those used for art and photography.^[16][18][20]

Wood-free paper has a number of advantages over paper that contains mechanical pulp:

• It is more resistant to yellowing. This is because the lignin, which is the main cause of paper yellowing, has been removed from the pulp.^[17][21][22]
• It is stronger. This is because the cellulose fibers in wood-free paper are longer and more uniform than the fibers in mechanical pulp.^[10]
• It is more durable. This is because wood-free paper is less likely to tear or crease.^[10]
• It is smoother. This is because the surface of wood-free paper is smoother than the surface of paper that contains mechanical pulp.^[10]

Wood-free paper is used in a variety of applications:

• Writing and printing papers: Wood-free paper is the most common type of paper used for writing and printing.^[23] It is available in a variety of weights and finishes, making it ideal for a variety of applications^[17]
• Envelopes: Wood-free paper is the most common type of paper used for envelopes.^[24][25] It is available in a variety of colors and finishes, making it ideal for a variety of occasions.
• Art and photography papers: Wood-free paper is the most common type of paper used for art and photography.^[23] It is available in a variety of weights and finishes, making it ideal for a variety of projects.
• Other applications: Wood-free paper is also used in a variety of other applications, such as packaging, labels, and currency^[16][26]

Types of wood-free papers

Wood-free paper is made from non-wood materials, such as cotton, hemp, linen, and bamboo.^[18][27][28] 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: This is the most common type of wood-free paper. It is made from wood pulp that has been treated with chemicals to remove the lignin. Lignin is the natural adhesive that holds wood fibers together.^[29]
• Non-wood pulp: This is a type of wood-free paper that is made from non-wood materials, such as cotton, hemp, linen, and bamboo.^[16]

Tissue pulp paper is smooth and opaque, making it ideal for printing and writing.^[30][31][32] 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.^[33][34][35] 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:

• Cotton paper:

  

  Cotton paper texture

  This is made from 100% cotton fibers, making it one of the most luxurious and expensive types of paper. It is known for its strength, durability, and high opacity. Cotton paper is often used for high-end printing and writing applications, as well as for greeting cards, stationery, and other special projects.^{[citation needed][36]}
• Hemp paper:

  

  Hemp paper

  This is made from hemp fibers, which are strong and durable.^[37] Hemp paper is also biodegradable and recyclable, making it a sustainable choice. It is often used for packaging, as well as for greeting cards, stationery, and other special projects.
• Linen paper: This is made from linen fibers, which are also strong and durable. Linen paper has a natural sheen and is often used for high-end printing and writing applications.^[38]
• Bamboo paper:

  

  Bamboo paper

  This is made from bamboo fibers, which are renewable and sustainable. Bamboo paper is also strong and durable, and it has a smooth, matte finish.^[39] It is often used for packaging, as well as for greeting cards, stationery, and other special projects.

Wood-free paper is a good choice for applications where a high-quality, durable paper is needed.^[10] 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.^[40]

Advantages and benefits of wood-free paper

1. Conservation of Forests: One of the key advantages of wood-free paper is its ability to reduce the demand for wood pulp derived from trees. This conservation of forests persevering valuable ecosystems and biodiversity. Wood-free paper production significantly contributes to the conservation of forests by reducing deforestation and protecting natural habitats.^[41][42]
2. Harder to Warp: Another key advantage of wood-free paper is its lesser likelihood to warp or curl.^[43]
3. Decreased Deforestation: The use of alternative fibers in timber-loose paper reduces the stress on forests, minimizing the need for big-scale deforestation. This helps protect touchy and ecologically valuable regions.^[44][45][46]
4. Decreased Carbon Footprint: wooden-loose paper generally has a decreased environmental effect as compared to standard wood-based total paper. The manufacturing system emits fewer greenhouse gases, consumes less strength,^{[clarification needed]} and requires less water.^[47][48] Additionally, it frequently includes fewer chemical treatments.
5. Usage of Agricultural Residues: Wooden-free paper can be made from agricultural residues like wheat straw, rice straw, and bagasse. Making use of those by-products of agriculture reduces waste and presents an extra source of revenue for farmers.^[49]
6. Advertising of Sustainable Farming Practices: The cultivation of opportunity fiber crops for paper manufacturing encourages sustainable agricultural practices. although vegetation frequently requires fewer insecticides and fertilizers as compared to traditional crops, lowering environmental impacts.
7. Waste discount and recycling: wooden-unfastened paper is often crafted from recycled materials. This supports recycling projects and reduces the demand for brand new raw materials. moreover, it emitted from landfills.
8. Diversification of supply Chains: depending completely on timber pulp can result in overexploitation of unique tree species and wooded area ecosystems. Incorporating alternative fibers diversifies the assets of uncooked materials for the paper industry, decreasing strain on precise varieties of timber.
9. Energy efficiency: wood-free paper manufacturing often requires much less electricity compared to conventional timber-based totally papertmanufacTuring. this is because the processing of opportunity fibers normally entails fewer steps and mucnergy-in-ergy-in depth remedies.
10. More advantageous Soil health: utilizing agricultural residues for paper manufacturing can enhance soil fitness by returning organic count to the soil. this may lead to better fertility and a normal soil structure.
11. Help for Rural communities: The manufacturing of timber-free paper using agricultural residues can create economic possibilities for rural communities. This will lead to improved livelihoods and sustainable improvement in areas where these resources are plentiful.
12. Monetary Viability and market demand: The demand for environmentally sustainable products, including wood-free paper, is on the rise. This presents economic opportunities for businesses that choose to invest in and produce eco-friendly paper products.
13. Alignment with Sustainability desires: the use of wood-loose paper aligns with global sustainability dreams, together with the ones outlined within the United Nations Sustainable Improvement Goals (SDGs). It contributes to desires related to accountable consumption and production (SDG 12) and existence on land (SDG 15).

Alternative Fibers: The Key Players

1. Agricultural Residues

Agricultural residues refer to the organic materials that are left over after crops are harvested.^[50][51] These residues include the stems, leaves, husks, and other parts of plants that are not used for food or other primary products.^[52][53] They are a significant component of agricultural ecosystems and have various potential uses, both beneficial and detrimental.^[54][55][56] Here's a detailed overview of agricultural residues:

Types of Agricultural Residues

1. Crop Residues:
   • Stems and Leaves: These are typically the above-ground portions of plants that remain after harvest.^{[57][58][59][60]} They are composed mainly of cellulose, hemicellulose, and lignin.
   • Husks and Straws: These are the protective coverings of seeds and grains, like rice husks and wheat straw.^[61][52]
   • Roots: After harvest, the roots of some plants may also be left in the ground.^[62][63][64]
2. Animal Manure:
   • Dung and Urine: Manure from livestock contains organic matter and nutrients that can be used as a soil conditioner or fertilizer.^[65][66][67]

Characteristics of Agricultural Residues

1. Chemical Composition:
   • They are primarily composed of organic compounds such as cellulose, hemicellulose, lignin, and various other polysaccharides.^[68][69][70] These materials provide structural support to plants.
2. Nutrient Content:
   • They contain a range of essential nutrients including nitrogen, phosphorus, potassium, and micronutrients.^{[citation needed]} However, the nutrient content varies depending on the type of residue and the plant it comes from.
3. Moisture Content:
   • This varies greatly depending on the type of residue, climate, and storage conditions.^[71] Some residues are relatively dry (e.g., straw), while others may have a higher moisture content (e.g., green crop residues).
4. Decomposition Rate:
   • The rate at which agricultural residues decompose depends on their chemical composition.^[72][73][74] For example, lignin-rich materials like wood take longer to break down compared to cellulose-rich materials like straw.

Uses and Applications

1. Soil Amendment:
   • Agricultural residues are commonly used to improve soil structure, moisture retention, and nutrient content.^[75][76][77] They act as organic matter, enhancing soil fertility.
2. Bioenergy Production:
   • Residues can be processed to produce biofuels like biogas, bioethanol, and bio-oil.^[78][79][80] This contributes to renewable energy production.
3. Livestock Bedding:
   • Straw and other crop residues can be used as bedding for livestock.^[81] This provides a comfortable and clean environment, reducing the risk of diseases.
4. Composting:
   • They are valuable components in composting operations, providing carbon-rich material that balances the nitrogen-rich materials (like green plant matter and manure).^[82][83][84]
5. Erosion Control:
   • Cover crops and crop residues left on the field surface can help prevent soil erosion by wind and water.^[85][86][87]
6. Mushroom Cultivation:
   • Certain agricultural residues, such as rice straw and sawdust, are used as substrates for growing mushrooms.^[88][89][90]

Challenges and Considerations

1. Nutrient Imbalance:
   • Depending on the type of residue, there may be an imbalance in the nutrient content, which may require supplementation.^[91]
2. Harvesting Practices:
   • Leaving residues on the field can have both positive (soil protection, organic matter addition) and negative (pest and disease carryover) consequences, depending on how it's managed.^[92]
3. Transport and Storage:
   • Handling and transporting large quantities of agricultural residues can be logistically challenging due to their bulkiness.
4. Environmental Impact:
   • If not managed properly, burning or improper disposal of residues can lead to air pollution and contribute to greenhouse gas emissions.^[93][94][95]

2. Cotton

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).^[96][97] Here's a detailed overview of cotton:

Botanical Characteristics

• Genus: Gossypium
• Family: Malvaceae
• Species: There are about 50 species of cotton plants, but only a few are cultivated for commercial purposes. The most common species used in commercial cotton production are Gossypium hirsutism (Upland cotton) and Gossypium barbadense (Pima or Egyptian cotton).

Cotton Cultivation

1. Climate: Cotton is primarily grown in regions with a warm climate. It requires a frost-free growing season of about 160 to 200 days.^[98][99]
2. Soil: Well-draining loam soils with good fertility are ideal for cotton cultivation.^[100][101]
3. Cultivation Practices:
   • Planting: Cotton seeds are planted in rows, and the plants are spaced out to allow for proper growth and air circulation.^[102]
   • Irrigation: Cotton requires regular watering, especially during dry spells.
   • Fertilization: Depending on the soil's nutrient content, supplementary fertilizers may be used.
4. Pest Management: Cotton plants are susceptible to various pests and diseases. Integrated Pest Management (IPM) practices are often employed to minimize chemical inputs.

Life Cycle

1. Germination and Growth: Cotton seeds germinate in warm soil. The plants grow into bushes with multiple branches, and flowers emerge at the nodes.
2. Flowering: Cotton plants produce large, showy flowers that are usually white or cream-colored. Each flower produces a cotton boll, which contains the seeds.
3. Boll Formation: After fertilization, the flower wilts, and the ovary enlarges to form a boll. Inside the boll, fibers develop around the seeds.
4. Harvesting: Cotton bolls mature and split open, revealing the cotton fibers. Harvesting involves mechanically picking the cotton or, in some cases, by hand.

Cotton Fiber

1. Chemical Composition: Cotton fibers are primarily composed of cellulose, a complex carbohydrate that provides strength and flexibility.
2. Properties:
   • Cotton fibers are soft, breathable, and absorbent, making them suitable for a wide range of textile applications.
   • They have good dye affinity, allowing for a wide range of colors and finishes.
3. Staple Length: The length of cotton fibers, known as the staple length, varies depending on the cotton variety. Longer staple lengths are typically associated with higher-quality cotton.

Cotton Products and Applications

1. Textiles: Cotton is used to produce a wide range of textile products including clothing, linens, towels, and upholstery.
2. Nonwoven Fabrics: Cotton fibers are also used in nonwoven applications like medical dressings, wipes, and filters.
3. Seed Products: Cotton seeds are crushed to extract oil, which is used in cooking and various industrial applications. The remaining seed meal is used in animal feed.

Challenges and Considerations

1. Pesticide Use: Cotton is susceptible to pests, and conventional farming often involves the use of pesticides. Sustainable and organic cotton production methods aim to reduce chemical inputs.
2. Water Usage: Cotton cultivation can be water-intensive, particularly in arid regions. Efficient irrigation practices and water-saving technologies are being implemented.
3. Genetic Modification: Some varieties of cotton are genetically modified (GM) to resist pests or tolerate specific environmental conditions. This has both benefits and controversies.

3. Hemp

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:

Botanical Characteristics

• Genus: Cannabis
• Family: Cannabaceae
• Species: Cannabis sativa is one of several species within the Cannabis genus. There are also subspecies, such as Cannabis sativa subsp. indica.

Hemp Cultivation

1. Climate: Hemp is a robust plant that can grow in a wide range of climates. It is adaptable and can thrive in temperate, subtropical, and tropical climates.
2. Soil: Well-draining, loamy soils with good fertility are ideal for hemp cultivation. Hemp can also grow in various soil types, including sandy and clayey soils.
3. Cultivation Practices:
   • Planting: Hemp seeds are typically sown directly in the field. The spacing between plants depends on the specific variety and intended use (fiber, seed, or cannabinoid production).
   • Irrigation: Hemp requires regular watering, especially during dry spells, but it can also tolerate drought conditions.
4. Pest and Disease Management: While hemp is generally considered a hardy plant, it can still be susceptible to certain pests and diseases. Integrated pest management (IPM) practices are used to address these issues.

Life Cycle

1. Germination and Growth: Hemp seeds germinate in warm soil. The plant grows into a tall, upright stem with multiple branches. It is a fast-growing plant.
2. Flowering: Depending on the variety and purpose of cultivation, hemp plants can flower in as little as 60–90 days. The flowers of female plants are the primary site of cannabinoid production.
3. Seed Formation: In some varieties, female plants produce seeds after pollination. These seeds can be harvested and used for various purposes, including food and oil production.
4. Harvesting: The timing of hemp harvest depends on the intended use. For fiber production, the plants are typically harvested before flowering. For seed production, they are left to mature longer. For cannabinoids, the harvest occurs when the plants have reached the desired cannabinoid content.

Hemp Products and Applications

1. Fiber: Hemp fibers are known for their strength and durability. They can be used to make a wide range of products including textiles, ropes, paper, and construction materials.
2. Seeds: Hemp seeds are rich in protein, healthy fats, and various nutrients. They are used in food products like hemp oil, hemp milk, protein powders, and as a whole food ingredient.
3. Hemp Oil: Hemp seeds can be cold-pressed to extract oil, which is used in cooking, skincare products, and industrial applications.
4. Cannabinoids (CBD and THC): Some varieties of hemp are bred for their cannabinoid content. Cannabidiol (CBD) and tetrahydrocannabinol (THC) are two of the most well-known cannabinoids. Hemp-derived CBD is used in various wellness and medicinal products.
5. Industrial Applications: Hemp can be used to make a wide range of industrial products including biofuels, biodegradable plastics, building materials, and more.

Challenges and Considerations

1. Regulatory Environment: The legal status of hemp varies by country and region. Many places have strict regulations around cultivation due to its association with cannabis.
2. Pollination: For some purposes (such as cannabinoid production), preventing male plants from pollinating female plants is essential to maintain high cannabinoid content.
3. Crop Uniformity: Hemp crops can show a wide range of genetic diversity, which can lead to variability in desired traits. Selective breeding and genetic techniques are used to address this.

See also

• Coated fine paper
• Woodfree uncoated paper
• Tree-free paper