Wet End Chemistry Characteristics Of DQP Bleached Wheat Straw And Acacia Pulp Cooperated To Make The High-grade P&W Paper

Wheat straw is a possible alternative to the hardwood kraft fiber use in the production of fine paper. It is available in abundance. Its fiber dimensions are quite similar to commercial hardwood pulp as well, having a length of approximately 0.7 mm.Therefore, the exploitation and application of wheat straw could be propitious to make up the lack for paper material. Wet end chemistry characteristics of DQP bleached wheat straw and Acacia pulp cooperated to make the high-grade culture paper was studied in this thesis.It provide the theoretical basis and technical support for the promotion and application of the environmentally friendly bleached (DQP) wheat straw.A holistic view of the use of wheat straw bleached by two different bleaching sequences (DQP and CEH) was to replace a portion of Acacia for fine paper manufacturing. For raw pulps, wheat straw showed physical properties suitable for the replacement of Acacia fiber with minimal or no refining.DQP bleached wheat straw was more difficult to dewatering followed by CEH bleached wheat straw and Acacia fiber.However, the use of suitable dewatering/retention wet-end chemicals can improve dewatering significantly.When used in a furnish, DQP bleached wheat straw gave improved tensile, tear and bending stiffness properties compared to Acacia. Wheat straw (CEH bleached) gave similar mechanical properties to Acacia.In the study of adsorption,DQP bleached wheat straw was more difficult to adsorption followed by CEH bleached wheat straw and Acacia fiber.Therefore more retention and dewatering wet-end chemicals were required.The results accord with retention and dewatering.It was found the the surface charge was changed because of the refining.However,the total charge remained unchanged.Comparing the properties of two kinds of fines,the secondary fines were better than primary fines.Some work was done trying to examine the fines fraction of DQP bleached wheat straw. Bauer McNett was used to fractionate the pulp followed by light microscopy,AFM and CLSM.The study shown the micro-fibres were very beautifully located in a nice pattern on the surface of long fibers;all kinds of overlapping and conglutina-tion occurred frequently on the surface of fines.Comparing with the fibers the fines,there are more extract and lignin on the surface of fibers.