Study of Agave Fiber-Reinforced Biocomposite Films

Abstract

Thermoplastic resins (linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and polypropylene (PP)) reinforced by different content ratios of raw agave fibers were prepared and characterized in terms of their mechanical, thermal, and chemical properties as well as their morphology. The morphological properties of agave fibers and films were characterized by scanning electron microscopy and the variations in chemical interactions between the filler and matrix materials were studied using Fourier-transform infrared spectroscopy. No significant chemical interaction between the filler and matrix was observed. Melting point and crystallinity of the composites were evaluated for the effect of agave fiber on thermal properties of the composites, and modulus and yield strength parameters were inspected for mechanical analysis. While addition of natural fillers did not affect the overall thermal properties of the composite materials, elastic modulus and yielding stress exhibited direct correlation to the filler content and increased as the fiber content was increased. The highest elastic moduli were achieved with 20 wt % agave fiber for all the three composites. The values were increased by 319.3%, 69.2%, and 57.2%, for LLDPE, HDPE, and PP, respectively. The optimum yield stresses were achieved with 20 wt % fiber for LLDPE increasing by 84.2% and with 30 wt % for both HDPE and PP, increasing by 52% and 12.3% respectively.

Keywords: agave fiber; biocomposites; mechanical properties; polyethylene; polypropylene; thermoplastic.

Figure 1

Images of agave fiber reinforced thermoplastic composite films. (a–e), LLDPE reinforced with agave fiber at 0 wt %, 5 wt %, 10 wt %, 20 wt % and 30 wt %; (f–j), HDPE reinforced with agave fiber at 0 wt %, 5 wt %, 10 wt %, 20 wt % and 30 wt %; (k–o), PP reinforced with agave fiber at 0 wt %, 5 wt %, 10 wt %, 20 wt % and 30 wt %.

Figure 2

Agave fibers: (a) before and (b) after washing treatment; SEM images of agave fibers: (c) and (d): at low magnification showing individual fibers, (e) and (f) variations in fibers’ diameter, and: (g) and (h): surface roughness of agave fiber.

Figure 3

Cross-sectional SEM micrographs of PP/agave fiber films: (a) PP control group, (b–f) PP: agave fiber 80:20 wt %.

Figure 4

FT-IR spectra of agave fiber reinforced thermoplastic-based composite films: (a) LLDPE with agave fiber; (b) HDPE with agave fiber; (c) PP with agave fiber.

Figure 5

Elastic modulus (E) region of biocomposite films from stress vs. strain graph.

Figure 6

Elastic modulus (E) of biocomposites consisting of different fiber content.

Figure 7

Yield stress (σ) of the composite films and thermoplastic control films.

Figure 8

Effect of agave fiber content on melting points of LLDPE, HDPE and PP; no significant variation in T_m was observed.

Figure 9

Glass transition temperatures of various composites with different agave fiber contents.