Study on the Application of Kenaf Core as a Composite Reinforcement: Injection Molding of Kenaf Core/Poly(l-lactide) Compounds

• Published in: Journal of natural fibers Vol. 14; no. 5; pp. 666 - 677
• Main Authors: Kawahara, Yutaka, Saito, Yo, Yamamoto, Kiyoshi, Ikeda, Yoshimitsu, Nishikawa, Yukihiro
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03-09-2017; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: composite; Distillation; dry-distillation; Drying ovens; Fibers; Hydrophobicity; Impact strength; Injection; Injection molding; Kenaf; kenaf core; Microwave oven; Moisture content; Molecular weight; Physical properties; PLLA; Poly(L-lactide); Polylactic acid; surface affinity of reinforcement; Tensile properties; Transesterification; Vaporization; 增强的表面亲和力; 复合材料; 槿麻核
• ISSN: 1544-0478; 1544-046X
• DOI: 10.1080/15440478.2016.1266293

Injection molding was performed using poly(l-lactide) (PLLA) as a matrix and by varying the reinforcements, i.e., dry-distilled kenaf core (D-core) or untreated kenaf bast fibers, and the physical properties for these composites were subsequently compared. The dry-distillation was able to reduce the moisture content of D-core by a maximum of 4.2% as compared with untreated control core. As a result, the hydrophobicity was increased, which contributed to favorable Charpy impact strength and tensile properties of the D-core/PLLA composite relative to the kenaf bast fiber/PLLA composite. Moreover, the puffing phenomenon, which arises when heating with a microwave oven due to the vaporization of water dispersed within the interfacial regions and associated softening of the PLLA matrix by the heated vapor, was completely suppressed for the D-core/PLLA composite, whereas a large puffing ratio was observed for the kenaf bast fiber/PLLA composite. Reducing the moisture content also effectively suppressed the occurrence of transesterification reactions, leading to a decrease in the molecular weight of PLLA. However, the apparent nucleation effect of the D-core remains slightly inferior to that for the hydrophilic bast fibers due to its stronger affinity for PLLA molecules.