Читать книгу Mechanical and Dynamic Properties of Biocomposites - Группа авторов - Страница 24

A tropical plant, pineapple (Ananas comosus) belongs to the family of bromeliad (Bromeliaceae). In South America, it is next in line to banana and mango in total production across the globe [39]. Pineapple leaf fibers (PALFs) are waste products when cultivating pineapples and are extracted from pineapple leaves. It has a significant mechanical behavior, because it is high in cellulose (70–82%) as well as in crystallinity (44–60%) [40]. Combining these properties with that of Kenaf fiber, excellent tensile and flexural strengths from FRP composite are obtained, which promises a good material for different applications [4].

Aji et al. [41] studied hybridized Kenaf/PALF specimens with HDPE reinforcement, using 1 : 1 fiber ratio. They investigated into how the size of fiber and its loadings affected the mechanical responses of the hybrid biocomposites (Table 1.8). The four reinforcement lengths considered at a fiber loading range of 10–70% were 0.25, 0.50, 0.75, and 2.00 mm. The smallest of these fiber lengths (0.25 mm) yielded the best result in terms of its flexural and tensile properties, while both 0.75 and 2 mm exhibited enhancement in impact strength. As observed further, an increase in the fiber length reduced some of the mechanical behaviors, which is credited to the entanglement in fibers as against fiber attrition. An inverse proportionality was established between the tensile and impact properties, as the rule of mixture was satisfied by flexural strength. The adhesion between the fiber and the matrix interface was good, as evaluated by scanning electron microscopy (SEM).

Table 1.8 Mechanical behaviors of kenaf/PALF, roselle/sisal, and silk/sisal FRP hybrid composites.

Source: Nguyen et al. [4]. © 2017, Elsevier.

Hybrid biocomposites	Fibre ratio (by weight or volume)	Flexural modulus (GPa)	Flexural strength (MPa)	Tensile modulus (GPa)	Tensile strength (MPa)	Impact strength (kJ/m2)
Kenaf/PALF	1 : 1 (At 0.25 mm fiber length and 60% fiber loading)	4.114	34.01	0.874	32.24	6.167
	1 : 1
Sisal/roselle	Dry condition, fiber length = 15 cm	—	76.5	—	58.7	1.30
Wet condition, fiber length = 15 cm	—	62.9	—	44.9	1.28
Sisal/silk	1 : 1, fiber length = 20 mm
Untreated	—	46.18	—	18.95	—
Alkali treatment	—	54.74	—	23.61	—