💡 Comparison of the production of grass pulp and wood pulp.
Because it uses a lot less raw material and is recyclable and compostable, grass paper is a green alternative to traditional paper in every sense of the term.
Test Result Comparison: Wood Pulp Paper VS Grass Pulp Paper
This comparison outlines the typical differences between paper made from wood pulp and paper made from grass pulp, focusing on key physical and chemical properties.
Note. that the exact values can vary based on the specific species of wood/grass, pulping process, and papermaking techniques.
⚙️ Physical Properties:
| Property | Wood Pulp Paper | Grass Pulp Paper | Explanation |
| Tensile Strength (kN/m) | 30-80 | 20-50 | Wood pulp generally forms longer fibers, creating stronger inter-fiber bonds and higher tensile strength. Grass fibers are shorter and result in lower tensile strength. |
| Burst Strength (kPa) | 200-600 | 150-400 | Similar to tensile strength, the longer wood fibers contribute to better resistance against bursting. Grass pulp paper has a lower resistance and can burst more easily. |
| Tear Strength (mN) | 8-20 | 4-12 | Again, the fiber length is key. Longer wood fibers translate to higher tear resistance. Grass fibers, being shorter, tear more readily. |
| Folding Endurance (Double Folds) | 500-5000 | 200-1500 | Wood pulp paper, especially hardwood pulp, demonstrates superior folding endurance due to its fiber structure. Grass pulp paper, due to its inherent stiffness and shorter fibers, has a lower folding endurance. |
| Brightness (%) | 80-95 (bleached) | 60-80 (bleached) | Wood pulp, particularly softwood, can achieve higher brightness levels after bleaching than grass pulp, which contains more lignin and other light-absorbing compounds. |
| Smoothness (Bendtsen ml/min) | 50-300 | 100-500 | Wood pulp paper can be calendered to achieve a smoother surface finish. Grass pulp paper tends to be rougher because of the shorter and stiffer fibers, even after calendering. |
| Opacity (%) | 90-98 | 85-95 | Wood pulp paper generally exhibits slightly higher opacity due to light scattering within its fiber structure. Grass pulp paper has slightly lower opacity. |
| Basis Weight (g/m²) | Can vary widely (e.g., 40-300) | Can vary widely (e.g., 40-300) | Basis weight refers to the weight of paper per unit area and can be adjusted during papermaking for both wood and grass pulp papers. |
🧪 Chemical Properties:
| Property | Wood Pulp Paper | Grass Pulp Paper | Explanation |
| pH | 4.5-7.5 (can be adjusted) | 6.5-8.5 (can be adjusted) | Grass pulp naturally tends to be more alkaline than wood pulp. However, the pH of both can be adjusted during the papermaking process through the use of additives. |
| Lignin Content (%) | <5 (bleached), 1-5 (unbleached) | 5-15 | Grass contains significantly more lignin than wood, contributing to its lower brightness and different aging properties. Even after bleaching, grass pulp paper retains more lignin. |
| Cellulose Content (%) | 40-45 | 35-45 | While both contain cellulose as the primary structural component, wood pulp generally has marginally higher cellulose content. |
| Ash Content (%) | <1 (wood) | 2-10 | Grass contains more silica and other minerals that remain as ash after combustion, leading to a higher ash content compared to wood pulp. |
Summary
- Grass fibers, being shorter, tear more readily.
- Grass pulp paper has a lower resistance and can burst more easily.
- Grass pulp contains significantly more lignin than wood, contributing to its lower brightness and different aging properties. Even after bleaching, grass pulp paper retains more lignin.
- Wood pulp, particularly softwood, can achieve higher brightness levels after bleaching than grass pulp
- Grass pulp paper, due to its inherent stiffness and shorter fibers, has a lower folding endurance.
🌿 However, grass pulp presents a sustainable alternative with specific advantages in certain applications.
Examples & Specifics:
- Newspaper: Traditionally made primarily from wood pulp (newsprint grade), increasingly incorporating recycled fibers and even some grass pulp to reduce costs and environmental impact.
- Writing Paper: Typically made from wood pulp, particularly hardwood pulp for smoothness and brightness. Higher grades might utilize cotton fibers.
- Packaging Paper: Kraft paper, made from wood pulp, is known for its strength. Grass pulp can be blended for certain packaging applications where high strength is not critical.
💡 Conclusion:
Because of its advantageous fiber qualities, wood pulp continues to be the most popular source for papermaking. But in some situations, grass pulp offers a sustainable substitute with unique benefits. To lessen dependency on wood pulp and encourage environmental sustainability, ongoing research and development is concentrated on enhancing the qualities of grass pulp paper and increasing its uses.
Reference
– https://www.biologischverpacken.de/en/guide/materials/grass-paper
– https://innovationorigins.com/en/sustainable-paper-alternative-comes-from-grass-here-is-how/
– https://at.duni.com/en/magazin/verpackungen/graspapier-verpackungen
– https://label.co.uk/sustainable-labels/grass-paper-labels/