FEATURE / BAMBOO FIBER Figure 3. SEM micrographs of the polished cross-sectional areas of (a) BF-PP-TCF (0/0) and (b) BFPP-TCF (0/90) composites indicating BF-PP and TCF tape region. strength and modulus of the BF-PP increased by ~53% and ~54% respectively. The enhancement in strength on adding TCF layers was also due to the inherent strength of the TCF than BF-PP, thus resists higher stress upon failure compared to BFPP17 . Figure 5d represents the SEM image of flexural fractured BF-PP sample. The nature of failure was ductile which was attributed to the ductile nature of PP. Failure in both BF-PP-TCF (0/0) and BF-PPTCF (0/90) occurred at the tape and propagated to the BF-PP region as depicted in Figure 5e and f. The failure between the two TCF layer might be due to the poor interfacial strength between the TCF layers resulted from process variability. Both overmolded samples exhibited delamination at the weld line representing possibilities to improve interface strength. This can be achieved by various methods as plasma treatment or etching on the surface, adding PP modifiers as PP is hydrophobic in nature etc18 . Figure 4. (a) Flexural properties and (b) Typical flexural load-displacement curve of BF-PP, BF-PP-TCF (0/0) and BF-PP-TCF (0/90) composites. Interlaminar Shear Strength (ILSS) Testing ILSS properties of BF-PP and BF-PP-TCF composites are presented in the Figure 6. ILSS of BF-PP composites significantly increased from 5.53 MPa to 18.98 MPa and to 11.27 MPa on overmolding of 0/0 and 0/90 TCF layers. ILSS of BF-PP composites provided an understanding of shear strength of PP aided by the BF-PP interface19 . The increase in ILSS on overmolding TCF could be due to the effective stress transfer between the continuous TCF fiber and matrix19 . Furthermore, excellent interfacial bonding between BF-PP and TCF tape might be the other reason for increase in ILSS. It is well known that the ILSS of a composite is significantly influenced by the fiber-matrix interfacial shear strength, matrix characteristics, void content, fabrication defects, dry fiber strands and internal microcracks9 . Alwekar et al.7 also observed 33-41% higher ILSS for CFRT tape overmolded LFT as compared to LFT. (a) (b) 26 | SAMPE JOURNAL | MARCH APRIL 2023 www. sampe.orghttp://www.sampe.org