Bamboo Dissolving Pulp Production Based On Acetic Acid Pre-hydrolysis And Its Application

Dissolving pulp is used as a raw material in the manufacture of various cellulose-derived products and textile fibers. Due to the consistent growth in rayon demand, linters and wood supplied to produce dissolving pulp can hardly meet the gap in the commercial production. Bamboo has been demonstrated to be a good source for dissolving pulp due to its abundance and short growth period. Though the manufacture of dissolving pulp is commercially viable, the overall fiber line yield for dissolving pulp production rarely exceeds 35% and normally retains around 30%. So studying on the manufacturingtechnologies and finding an optimal solution of bamboo dissolving pulp production can not only benefit meritof mills, but also promote the development of bamboo industry.In the work described in this thesis,the acetic acid pre-hydrolysis kraft process was used to produce bamboo dissolving pulp. During the pre-hydrolysis process, elevating temperature leads to the lose of bamboo yield, when temperature overtops 160oC,the reaction tends to be more drastic and the yiled decreased more rapidly. The addition of acetic acid(below 2.5%) does not much affect the pre-hydrolysis yield under the same reaction temperature below 160oC. Compare to the reaction temperature, holding time of pre-hydrolysis turns out to be less influence on the yield. Monosaccharides such as xylose,glucose,mannose,galactose and arabinose were typically exsited in the bamboo hydrolysate.During the reaction, Furfural and HMF would formedasproducts from dehydration of pentose and hexose. The first-order degradation kinetic models were established for glucose and xylose in a simulation experiment,whose apparent activation energy were 99.89 kjmol-1 and 99.68 kjmol-1。The pre-hydrolyzed bamboo chips were cooked in kraft method.Effects of temperature and cooking time on pulp yield and performance were discussed.It has been found that higher temperature in pre-hydrolysis would result in lower pulp yield and kappa number.In cooking time from 30 min to 90 min,pulp yield and kappa number keeps descending,however,both the two values would gain a slight rise after 120 min. The oxygen delignification, cold caustic extractionand D0-(EP)-D1 bleaching could improved the pulp performance effectively via selected reducing lignin and hemicellulosecontent.The dissolving pulp from bamboo was produced with 93%α-cellulose,90%ISO brightness,959 m L/g viscosity,5.23% xylans and 0.17% ash, which was suitable for viscose grade pulp.The overall yield on the basis of raw material was 37%,which was higher than other documented stuty on bamboo dissolving pulp production.Prehydrolysis kraft pulp and dissolving pulp were used to prepare TOCNs and cellulosic films through TEMPO/Na Cl O/Na Br oxidation system in this study.The TEMPO-mediated oxidation shortensthe length of the fiber and cause the increasing of fine content. At the same time, the fiber curl and kink index decreased notably after oxidation when compared with the original pulp. The carboxylate contents in oxidized prehydrolysis kraft pulp and dissolving pulp were quite different when apply the same reaction conditions,the value was 0.83mmol/g.o.d.p and 0.88mmol/g.o.d.p,respectively.In this work, TEMPO-oxidized pulps(TOP) and TOCNs from different materials were used to prepare two types of cellulosic films.TOCN film, tends to have higher transmittance, Young’s modulus and tensile strength than corresponding TOP film.Furthermore,the above-mentioned performance of film prepare from dissolving pulp were better than that prepared from prehydrolysis kraft pulp.The Young’s moduli and tensile strength of the TOCNs film from dissolving pulp were 5.8±0.3GPa and 61±3MPa, and transmittance of it was above 90%.