Alkali Treatment and Coupling Agent

In this treatment, parameters such as type and concentration of the alkali solution, operational temperature, temperature treatment time, material strength, as well as the applied additives are considered. Optimal conditions of mercerization ensure the improvement of tensile properties and absorption characteristics, which are important 

The alkaline treatment promotes the removal of partially amorphous constituents such as hemicelluloses, lignin, waxes and oils soluble in alkahne solution, and therefore reduces the level of fiber aggregation, making a surface rougher. 

During the alkaline treatment, the OH groups present in the fibers react with sodium hydroxide according to Equation 10.1. 

Sipiao et al. [37] studied the mechanical properties of high-density polyethylene (HDPE) composites reinforced with palm fiber-treated alkali solution. 

Firstly, fibers were dried at 50°C for an hour, and after being groxmd in a mill, finally sieved to obtain a sample that passed through a 45 mesh. To remove the soluble extractives and to fadhtate adhesion between fibers and matrix, palm fibers were pretreated with sodium hydroxide solution (1% w/w) for an hour xmder constant stirring at room temperature. Once the time of treatment was reached, the solution was filtered in a vacuum filter and fibers were washed with distilled water xmtil neutral pH was attained. Then, fibers were dried in an oven at 50°C for 24 hours. 

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