جستجوی مقالات مرتبط با کلیدواژه « ساقه ذرت » در نشریات گروه « جنگلداری »

In this study, for the useful consumption of residue materials that have no specific consumption and are waste, it was started making the particleboard from the mixing of corn stalk, wheat straw and industrial wood particles. Then, the physical and mechanical properties of the boards were measured. Because of the consumption of these raw materials that have a low price (if possible), it can be reduce the cost of production of this type of product. For this purpose, corn stalk, wheat straw and industrial wood particles at levels of 0:100, 25:75 and 50:50, press temperature of 160 and 180° C and 12 percent of urea formaldehyde resin based on the dry weight of the particles were used for the production of particleboards. The physical and mechanical properties of the boards including thickness swelling within 2 and 24 hours immersion in water, bending strength, modulus of elasticity and internal bonding were measured and all the data were statistically analyzed. The results of this research showed that the increase in corn stalk and wheat straw in the mixture showed in increased thickness swelling within 2 and 24 hours immersion in water. It means increasing the amount of corn stalks and wheat straw had a negative effect on the thickness swelling of the boards. The amount of bending strength, modulus of elasticity and internal bonding decreased with the increase of corn stalk and wheat straw particles in the boards and there was a significant difference between different levels of wheat straw and corn stalks. Also press temperature increase from 160 to 180 ° C had a significant effect on all the properties of the boards and improved the physical and mechanical properties of the boards. Increasing the temperature of the press also had a significant effect on all the properties of the boards and improved the properties. According to the results of this research, using corn stalk, wheat straw and industrial wood particles, increased significantly the dimensional stability of the boards. Bending strength, modulus of elasticity and internal bonding in control samples showed the highest values. But compared to the properties of the boards produced by EN standard, using 25% corn stalk and wheat straw, 12% urea formaldehyde resin and press temperature of 160 ° C, can be produced particleboards with favorable properties. This is a positive result for the use of mixing this kind of agricultural wastes including corn stalk and wheat straw, following that the prevention of environmental pollution caused by the burning of these compounds.

In order to investigate the potential of two agricultural residues (cotton and corn stalks), laboratory MDF boards were produced using fibers generated applying ten minutes steaming at 175 ºC, defibrated with 25 centimeters single disc refiner. Three press temperatures (170, 180 and 190 ºC) were used. For board pressing. Boards after conditioning at 65% RH and 21 ºC and then test samples were prepared according to relevant EN standard. All tests were performed according to relevant EN standard methods and then analyzed. The results indicate that the strength (MOR and MOE) of boards produced from corn stalks is almost 25% higher than those from cotton stalks. However no significant difference was observed for internal bonds of boards. Thickness swelling of MDF boards from corn stalks was lower than cotton stalks. Comparing the results with the strength of boards produced from beech wood showed the similarity between corn stalks and beech wood, but the strength of MDF boards from cotton stalks was lower than those produced from beech wood. Our results fulfill the minimum EN requirement.

Soda and soda-AQ pulping of corn stalk applying different charges of active alkali and pulping time was studied. The average value of fiber length, diameter and cell wall thickness were measured as 1.03 mm, 23.64 µm and 5.26 µm, respectively. The content of alcohol-acetone extractives, cellulose, lignin, extractives soluble in 1% NaOH and ash content of corn stalk were determined as 15%, 51.2%, 23%, 45.95% and 2%, respectively. Pulping with four levels of sodium hydroxide (12, 14, 16 and 18%, based on NaOH), and two cooking times (15 and 30 minutes) and constant cooking temperature at 145 ºC was performed. 0.1% AQ was added to soda/AQ cooking liquor. After analyzing the pulping yield and kappa number, two pulps were selected (NaOH; 12, 18%, cooking time; 15 minutes and cooking temperature; 145 ºC) as brown and bleachable stock, respectively. Eventhougth addition of 0.1% AQ showed no significant effect on pulping yield, but its effect on paper strength properties was significant. The result of handsheet evaluation revealed that the strength of pulp produced applying 18% NaOH, 0.1% AQ, and 15 minutes pulping time with breaking length of 8.21 km, and 80.59 N.m/g tensile index was superior to other pulping conditions. The tear index of the pulp produced applying 12% NaOH, 0.1% AQ and 15 minutes pulping time was determined as 10.60 mNm2/g. The burst index of pulp produced using 18% NaOH, 15 minutes pulping time without AQ addition, was the highest.

Buffered sulfite pulping of corn stalks was investigated. Four variables including sodium hydroxide charge at 12، 14، and 16%، sodium carbonate charge at 4 and 8%، pulping temperature at 145 and 165°C and pulping time of 15 and 30 minutes were evaluated. Results showed that increasing any of the four variables reduced both total yield and kappa number where the influence of pulping temperature was more pronounced. The highest total yield and accepted yield were measured to be 59. 7% and 51. 4%، respectively، applying pulping condition of 12% Na2SO3، 4% Na2CO3، 145°C and 15 minutes. The kappa number was 55. 4. The lowest total yield of 34. 1% and kappa number of 16 were achieved using 16% Na2SO3، 8% Na2CO3، 165°C and 30 minutes. Two pulps with the highest total yield and one with the lowest kappa number were selected for further evaluation. The tensile index of selected pulps varied between 52. 5 and 66. 6 Nm/g، and the relevant value for low yield pulp was 62. 9 N. m/g. Tear index varied between 5. 2 and 6. 7 mN. m2/g and the respective value for low yield pulp was 7. 3 mN. m2/g. The brightness values of the high yield pulps were measured to be 26 and 27% ISO، respectively and 40% for the low yield pulp. The results of this study revealed that brown pulp can be produced using corn stalks.