| Abstract:In this study, using Edgeworthia chrysantha as the raw material to prepare pulp with a high degree of polymerization, four differernt cooking methods were compared, including caustic soda method (NaOH), caustic soda-anthraquinone method (NaOH-AQ), kraft method (KP) and alkaline sodium sulfite-anthraquinone method (AS-AQ). The results showed that the degree of polymerization of Edgeworthia chrysantha pulp after AS-AQ cooking was the highest, and the pulp yield and whiteness were relatively high, with a large fiber length-to-width ratio. By the means of response surface analysis experiments, more suitable process conditions for preparing Edgeworthia chrysantha pulp with a high degree of polymerization were optimized as follows: the alkali dosage of 13.9%, the degree of sulfitation of 54.7%, the maximum temperature of 137°C, the holding time of 2.5 h and the liquid-to-solid ratio of 1:6. Under these conditions, the yield of R16 of Edgeworthia chrysantha pulp was 35.04%, the degree of polymerization reach up to 1942, the fiber length-to-width ratio was 189 and the whiteness of the paper was 63.08%ISO. Then the tensile index, burst index, and tear index were 41.99 N·m/g, 2.55 kPa·m2/g, and 22.03 mN·m2/g, respectively. Thus it can be seen that AS-AQ cooking here can effectively increase the degree of polymerization while ensuring the pulp yield, providing a technical basis for the development of pulp products with high added value. |