Britannica Sources used in this answer

How do fibre length and fibre bonding affect paper strength?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

paper mill — papermaking Paper mill in British Columbia, Canada.

In papermaking, the strength of paper is determined by a combination of factors, including the strength of individual fibres, the average length of the fibres, and the degree of interfibre bonding.1

Fibre Length

Fibre length is a critical factor in producing strong and durable paper. Generally, longer fibres contribute to higher strength, as they are better able to form a cohesive, interconnected structure within the sheet. However, there are practical limitations to using extremely long fibres in water-based manufacturing, as they tend to tangle and rope together during the formation process.2

Fibre Bonding

Interfibre bonding is essential for the structural integrity of paper. Natural cellulose fibres possess an inherent ability to bond together as the sheet dries, a process driven by interatomic forces known as hydrogen bonding or van der Waals forces.3

This bonding is significantly enhanced through mechanical action, such as beating or refining, which causes fibres to swell, become flexible, and fray into smaller fibrils. These treated fibres bond more readily as water is removed and the web is pressed, resulting in denser paper with higher tensile strength. Conversely, synthetic fibres often lack this natural bonding property, requiring the addition of adhesives to achieve similar coherence.32