The rice husk and DDGS were soaked in a 0.5 NaOH solution at room temperature maintaining a ratio of (500 mL alkali solution/50 g reinforcing filler) reinforcement was kept immersed in the alkali solution for 2 h. The fibers were then washed sever­al times with distilled water to remove any NaOH on the fiber surfaces, neutralized with dilute acetic acid, and again washed with distilled water. Below, in Fig. 12.3 are exposed photos of different reinforcements used in our study. Alkali treatment is one of the well-known processes to increase mechanical properties. The process alters the chemical content in crude fiber by removing lignin, pectin, hemi-cellulose, and changing the state of the materials from hydrophilic to hydrophobic. The large amount of hemi-cellulose lost made the fibers lose their cementing capacity and caused them to separate out from each other, making them finer42,43,44.