Toughness is actually the relationship between stress and strain. If the paper elongation is small, it will be difficult for the paper to undergo a large strain when subjected to external forces, and it will be easier to break. If the elongation is large, the paper will first be strained under the same force. fracture. In practice, paper with high tensile strength and low elongation does not necessarily have better performance than paper with low tensile strength and high elongation. The reason is that the latter can absorb more energy and show higher performance. Toughness.

Brittleness refers to the fact that the paper is easy to break, brittle and has poor toughness when subjected to impact force or bending force. The indicator of the brittleness of paper is the degree of brittleness, and the degree of brittleness of paper is expressed as a percentage of the decrease in the strength of the paper after a given crimp. Paper often has such a phenomenon in use, that is, when used under the conditions of impact, shaking or rubbing, paper with higher tensile strength is more likely to crack or break than paper with smaller tensile strength, which is only because The former is more brittle. Whether the paper is tough or brittle depends on the resistance and dispersibility of the paper sheet to stress. For papers with large stress dispersion ability, the stress acting on a certain part of the paper can be quickly dispersed and transmitted to a relatively large area, so that the stresses in each place are relatively balanced, thereby preventing partial breakage and destruction.