Fiber Flexibility vs Paper Flexibility

There is not direct relation between fiber flexibility and paper flexibility
fiber flexibility ↑ , inter-fiber bonding ↑, density of paper ↑, rigidity ↑, paper porosity ↓.
- Flexibility of fibers only affect the density, porosity and rigidity of paper, but not the flexibility of papers.

How to increase the flexibility of fibers?
- beating process.
- beating process will cause internal fibrillation (rupture of s2 microfibril layer, flexibility ↑) and external fibrillation (peeling effect on cell wall, ↑ surface area, ↑ bonding area)