When dry, cellulose polymer chains are held together by hydrogen bonds between the hydroxyl groups(OH) of nearby chains.Hydrogen bonding is so extensive that polymer chains are held fimly in place and are able to resist stresses applied to the fabric from twisting or stretching.

If the fabric is wet, however, wrinkling and shrinkage can occur. This occurs becasue water molecules disrupt the hydrogen bonds between the cellulose chains When the hydrogen bonds are broken cellulose the cellulsoe chains move relative to each other. As tghe fabric dries out hydrogen bonds between the cellulose chains reform and once again hold the chains tigthtly in their new position.

Permanent Press shirts are shirts that never need ironing. They have permanent creases and folds thanks to permanent crosslinks that exist between the cellulsoe chains. These crosslinks hold the chains in permanent position and prevents movement which causes wrinkles and shrinkage.