Pulp and Paper 



3117 



available by conventional technology. Some representative properties of labora- 

 tory-produced paper are summarized in table 25-9. 



Byrd ( 1 979b) and Horn ( 1 979) found that hemicellulose is primarily responsi- 

 ble for the high levels of bond adhesion and strength developed by press drying. 

 They found that lignin retards the initiation of flow and contributes little to bond 

 adhesion and strength, but does enhance wet-strength development in press- 

 dried high-yield pulps by flowing and protecting the hemicellulose bonds. 



CONVENTIONAL DRYING 



PRESS DRYING 



SHEET FORMATION 



DRYING 



WINDING 



Figure 25-19. — Paper drying systems. (Top) Conventional. (Bottom) Press drying. 

 (Drawing after Setterholm and Ince 1980.) 



