Puidukiud

Puidukiud, or wood fibers, are natural cellulose-based fibers derived from woody plants. They form the primary fibrous component of wood and are a fundamental raw material for papermaking and biocomposites. The fibers consist mainly of cellulose, with smaller amounts of hemicelluloses and lignin. The cellulose is organized into long, stiff microfibrils embedded in a matrix of hemicelluloses and lignin, giving high tensile strength and rigidity.

Source variation is notable: softwood fibers (from conifers) tend to be longer and more slender than hardwood fibers (from deciduous trees), a difference that influences properties such as strength, tear resistance, and the bulk of paper produced from them. Fiber length and microfibril angle contribute to processing behavior and end-use performance.

Production and processing involve pulping. Mechanical pulping preserves most of the lignin and yields high fiber length but produces darker, less chemically stable fibers. Chemical pulping, such as kraft pulping, removes much of the lignin, yielding brighter, stronger fibers suitable for high-quality papers. Chemi-thermomechanical pulping combines chemical pretreatment with mechanical refining. Bleaching further increases brightness. Recycled fibers can be incorporated into papermaking with deinking and refining steps.

Applications extend beyond traditional paper production to dissolving pulps for textile fibers (such as viscose and lyocell), reinforcement in polymer composites, specialty papers, filters, and nonwoven materials.

Sustainability considerations emphasize responsible forest management, recycling, and energy and chemical use in processing. Wood fiber properties and processing routes can be tailored to meet specific end-use requirements while aiming to minimize environmental impact.