A Review on the Effect of Various Chemical Treatments on the Mechanical Properties of Renewable Fiber-Reinforced Composites

Table 4

Effect of permanganate (KMnO₄) treatment on various biofibers.

S. no.	Fibers used	Type of chemical treatment	Effects	Ref.
1	Sisal	Permanganate treatment	Improvement in tensile strength.	[75]
2	Oil palm	Permanganate treatment	The treated fiber has highly fibrillated structure and hence very good fiber matrix adhesion. As a result, better tensile strength and modulus were observed	[100]
3	Sisal	Permanganate treatment	At 1% concentration of KMnO4 polar groups between fiber and matrix are formed leading to degradation of cellulose. The hydrophilic tendency of fiber decreases as the KMnO4 concentration increases up to an optimum.	[105]
4	Sisal	Permanganate treatment	At 1% concentration, higher degradation of cellulose occurred due to formation of polar group. Optimum properties were found to be better at 0.055% concentration. Tensile properties were observed between alkali and peroxide.	[144]
5	Sisal	Permanganate treatment	Improvement in interlaminar shear strength, tensile strength, and flexural properties compared to silane. But impact properties were lower than those of untreated fiber.	[145]
6	Banana	Permanganate treatment	An increase in thermal diffusivity, tensile strength, and tensile modulus by 16%, 6.4%, and 7.5%, respectively. However, flexural strength and modulus were found to have increases of 6% and 10%, respectively, which were lower compared to alkali and silane treatment.	[108]
7	Flax	Permanganate treatment	Improvement in tensile and moisture resistance as compared to alkali and silane-treated fibers.	[108]
8	Banana	Permanganate treatment	An increase in tensile strength and flexural strength by 5% and 10%, respectively. Increases in polarity and roughness of fiber were also observed.	[146]