Interfacial Adhesion Characteristics of Kenaf Fibres Subjected to Different Polymer Matrices and Fibre Treatments

Table 4

Main fibre pullout mechanisms and their brief remarks for the different types of fibre treatments used subjected to polyester matrix at dry loading conditions.

Polyester
Corresponding SEM figure	Fibre treatment	Brief remark/explanation	Main fibre pullout mechanism
Figure 6(a)	Untreated	Debonding of fibre observed associated with slight chipping of polyester because of impurities on fibre surfaces	Fibre breakage associated with slight torn fibre from the core of the fibre
Figure 6(b)	4% HCl	(i) Sign of fibre rupture from the core of the fibre after the pullout; (ii) Tendency of fibre to split from the main single fibre was high which contributed to many loose fibres; (iii) Fibre surfaces were smooth which ruined the interfacial adhesion strength of the fibre against the matrix	Brittle-like fracture at end of fibre was observed because of the acidic treatment
Figure 6(c)	6% HCl	(i) Sign of fibre contraction during the SFPT; (ii) Fibre surfaces were smooth which lowered the IAS of the fibre and matrix; (iii) Sign of micro cracks on fibre surfaces which cause the fibre to break during the pullout test	Brittle-like fracture at end of fibre was observed because of the acidic treatment
Figure 6(d)	4% NaOH	(i) Slight debonding of fibre with matrix; (ii) Fibre was torn apart from the main core fibre after the test indicating high interlocking capabilities of the fibre and matrix	Pure fibre breakage
Figure 6(e)	6% NaOH	Evidence of many fibre strands from the core of the fibre indicating that the fibre resisted the pullout force during the test	Ductile-like breakage was observed at the end of the fibre