ZnO nanorods were
prepared by the sol–gel method and characterized
using UV–visible absorption spectroscopy, Fourier transform
infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric
analysis/differential thermogravimetry (TGA/DTG), high-resolution
transmission electron microscopy (HR-TEM), field emission scanning
electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy
(EDAX). Banana fiber/polyester resin (BF/PE) biocomposites and BF/PE/MS/nano
ZnO nanobiocomposites were made using the untreated and chemically
treated (with NaOH, formic acid, acetic anhydride, hydrogen peroxide,
and potassium permanganate) banana fiber (BF), unsaturated polyester
resin (PE), molecular sieves (MS), and the prepared ZnO nanorods.
The KMnO
4
, Ac
2
O, and NaOH treatments enhanced
the thermal stability of the nanobiocomposites. Addition of 2% of
ZnO nanorods increased the tensile strength of all of the chemically
treated BF/PE/MS biocomposites. The chemical treatments alone decreased
(NaOH—15.4 MPa; KMnO
4
—14.5 MPa; H
2
O
2
—9.9 MPa; Ac
2
O—7.9 MPa; HCOOH—6.9
MPa) the compressive strength of the untreated BF/PE/MS biocomposite
(25.9 MPa). But the chemical treatment and addition of ZnO nanorods
enhanced the compressive strength effectively (48.5, 41.6, 39.4, 37.0,
and 34.6 MPa for NaOH, HCOOH, KMnO
4
, H
2
O
2
, and Ac
2
O treatments, respectively) compared to
the untreated BF/PE/MS biocomposites (24.0 MPa). The H
2
O
2
(69.0 MPa) and NaOH (62.9 MPa) treatments enhanced
the flexural strength of the untreated BF/PE biocomposites (51.6 MPa).
The addition of ZnO nanorods enhanced the flexural strength of all
of the chemically treated (except NaOH) BF/PE/MS biocomposites (55.7,
59.4, 79.0, and 67.4 MPa for HCOOH, Ac
2
O, H
2
O
2
, and KMnO
4
treatments, respectively). The
impact strengths of the biocomposites were enhanced by both chemical
treatments and addition of ZnO nanorods. The addition of ZnO nanorods
decreased the water absorption of the biocomposites significantly
from 24.3% for the untreated to a minimum of 14.5% for the H
2
O
2
-treated BF/PE/MS/ZnO nanobiocomposite.