Сhemical processing of corn head wrappers on fiber semi-finished products
Authors: Cheropkina Romaniia , Denysenko Anna 
Published: July 2021

Non-woody plant raw materials are of scientific interest in the effective processes of their chemical processing into fibrous semi-finished products and the properties of the finished product. A feature is the study of local species of annual plants that are among the most cultivated. Therefore, scientists are increasingly experimenting with corn waste for the possibility of their use in the manufacture of paper or cardboard, the study of their properties, but the results are not always stable.
Our work focuses on the use of corn waste in the form of cob wrappers and obtaining from them fibrous semi-finished products by the soda-soda method. The restraining factor of obtaining cellulose from this raw material is the variability of chemical composition, features of morphological structure, the insufficient study of delignification depending on the cost of active alkali, the influence of impregnation on this process, its duration, and temperature.
Wraps in the form of chaff were boiled with a solution at the consumption of active alkali 6 %, 10 %, and 14 % in units. Na2O by mass abs. dry. raw materials for impregnation for 15 min or without impregnation and subsequent cooking at a final temperature in the range of 100 0C - 160 0C for 15 or 30 min. The semi-finished products obtained as a result of cooking were ground, samples were made and their strength indicators were determined. It should be noted that the wrappers contain about twice less lignin, about 7.5-14 %, compared to wood – 23-28 %, which led to the choice of the minimum duration of cooking. However, the semi-finished products obtained from them are difficult to grind. This pattern is partly explained by the location of fibrils in the secondary wall of the middle layer S2 at an angle of 45-500 to the fiber axis, and the direction of fibrils in adjacent layers S1 and S3 of the cell wall is opposite, which inhibits splitting into individual fibrils.
It is shown that impregnation has a positive effect on the quality of raw material digestion and physical and mechanical properties. At a temperature of 130 0C for only 15 and 30 minutes of cooking with impregnation and the consumption of active alkali 14 % in units. Na2O achieved high strength of semi-finished products. Increasing the cooking temperature to 160 0C and the maximum consumption of active alkali to 14 % per unit. Na2O leads to a sharp decrease in the yield and strength of semi-finished products. This pattern is logically explained by theoretical provisions on the processes of delignification of raw materials. At the same time, the temperature and the consumption of alkali increase the destruction of the carbohydrate part, primarily its low-molecular fractions, which are responsible for the formation of strong hydrogen bonds between the fibers. The optimal conditions for delignification at a temperature of 160 0C can be considered the consumption of active alkali 10 % per unit. Na2O with impregnation and cooking time of 15 minutes and obtaining high yield cellulose.
The proposed raw materials for corn cob wrappers and technological modes of its chemical processing provide the production of fibrous semi-finished products with high strength.