puunsäie

Puunsäie is the Finnish term for the fibrous component of wood, referring to the elongated cells that provide mechanical strength in trees and wood products. It encompasses the cellulose-rich fibers embedded in a matrix of hemicelluloses and lignin, arranged in the plant cell walls. In wood anatomy, the majority of fibers are tracheids in softwoods and various fiber types in hardwoods; the secondary cell wall, especially the S2 layer with its microfibril angle, largely determines stiffness and strength.

The density and length of wood fibers vary by species, growth conditions, and age. Longer and well-librillated fibers generally yield stronger and more flexible wood products, while shorter fibers contribute to smoother surfaces in paper. The orientation and distribution of fibers influence the overall properties of the wood structure, including its ability to transport water and resist mechanical stress.

In industry, wood fiber is the principal raw material for papermaking and many wood-based composites. Mechanical pulping preserves more of the fiber length, whereas chemical pulping removes lignin to produce cellulose pulp; dissolving pulps for textiles are another example. Recycled wood fiber can be used in combination with virgin fiber, affecting properties and quality of the final product.

Environmental considerations: Wood fibers are renewable when sourced from sustainably managed forests; life-cycle assessments consider energy use, chemical consumption, and waste streams in pulping and papermaking.