Effect of Moisture content and loading positions on the Mechanical properties of New Rice for Africa (NERICA)

Abstract

The mechanical properties of New Rice for Africa, (NERICA) were determined on different moisture content levels of 12.5, 17 and 21.5% (db), and loading positions of major, minor, and intermediate diameters using the Instron Universal Testing Machine (UTM). The mechanical properties studied were the maximum load at rupture, compressive extension at maximum load, load at bioyield point, toughness, stiffness, compressive strength, energy at maximum load, and the maximum slope. Results obtained indicated that, the loading pattern and moisture content affected the mechanical properties determined (p < 0.05). Results showed that, maximum load at rupture, compressive extension, load at bio yield point, ranged from 363.73 to 50.92 N; 0.50 to 2.79 mm; and 11.58 to 6.78 N/mm 2 ; respectively for NERICA Raw-Paddy major diameter loading; and from 18.46 to 5.44 N; 0.92 to 2.52 mm; 9.01 to 4.08 N/mm 2 respectively for NERICA Raw-Paddy minor diameter loading. For the NERICA Parboiled-Milled, results at both major diameter and minor diameter loading positions ranged as follows; maximum load at rupture (156.08 to 44.94 N; 94.90 to 22.05 N); compressive extension (0.59 to 1.61 mm; 0.46 to 2.67 mm). Regression analysis were carried out on the mechanical properties with moisture content, and there was positive correlation between the parameters. There were significant effects of moisture content (p < 0.05) on all parameters studied.