The manufacture of chemical cellulose from wood



This paper discusses progress made and problems associated with the manufacture of chemically pure cellulose from wood. The yield of pure cellulose which can be obtained from any wood species is limited by the chemical composition of the wood starting material. An examination of the chemical composition of various native wood species emphasizes the special potential of the genus Populus. Improved yield and good economy of manufacture of cellulose depends on the development of purification processes which are effective on less thoroughly digested wood. Conditions are developed for the most effective way of carrying out extraction of raw pulp with hot caustic soda. These include very high consistencies and very short times at high temperatures. The best conditions for extraction with strong caustic soda at low temperature are also reviewed. The need for properly designed equipment for both these processes is stressed. The special problem of removal of mannan is discussed. Two objectives are put forth: a more economical cellulose with today's standard of purity and chemically pure cellulose from wood.