Properties of low density polyethylene/natural Rubber/chemical modified water hyacinth fibers (Eichhornia crassipes) composites

Abstract

The natural fiber composites of low density polyethylene (LDPE)/natural rubber (NR)/water hyacinth fibers (WHF) were studied. The composites were prepared by using Brabender Plasticorder at 160 oC with rotor speed of 50 rpm. The effect of WHF loading, compatibilizer and various types of chemical modification on mechanical properties, swelling behavior, morphological properties, thermal properties, spectroscopy infrared and XRD characterization of LDPE/NR/WHF composites were investigated. The compatibilizer used in this study was polyethylene-grafted-maleic anhydride (PE-g-MAH). The various types of chemical modification applied on LDPE/NR/WHF composites were poly (methyl methacrylate) (PMMA), poly (vinyl alcohol) (PVA), polyaniline (PANI), alkaline treatment (NaOH), and epoxy-ethylene diamine (EED). The compatibilized composites increased 15.38 % of tensile strength and 17.63 % of Young’s modulus but decreased 35.79 % of elongation at break, 26.21 % of molar sorption, and 4.22 % of average interparticle spacing. The PMMA modified LDPE/NR/WHF composites showed an increment of 29.18 % of tensile strength, 31.86 % of Young’s modulus, 35.66 % of elongation at break while a decrement of 5.36 % of molar sorption and 5.84 % of average interparticle spacing. The PVA modified LDPE/NR/WHF composites exhibited an improvement in tensile strength, Young’s modulus, and elongation at break by an increment of 23.96 %, 16.34 %, and 24.69 %, respectively whereas the molar sorption and average interparticle spacing decreased 3.22 % and 2.35 %, respectively. The PANI modified LDPE/NR/WHF composites increased 4.71 % of tensile strength, 24.46 % of Young’s modulus, 85.5 % of elongation at break but decreased 3.60 % of molar sorption and 11.29 % of average interparticle spacing. The NaOH modified WHF on LDPE/NR/WHF composites showed an increment of 2.46 %, 202.33 % and 68.77 %, respectively in tensile strength, Young’s modulus and elongation at break while a decrement of 25.30 % and 19.39 %, respectively in molar sorption and average interparticle spacing. The EED modified LDPE/NR/WHF composites increased 16.30 % of tensile strength, 17.13 % of Young’s modulus, and 507.05 % of elongation at break but decreased 8.6 % of molar sorption and 11.52 % of average interparticle spacing. The PE-g-MAH, PMMA, PVA, PANI, NaOH and EED modified LDPE/NR/WHF composites exhibited better thermal stability but lower % crystallinity except for PMMA modified LDPE/NR/WHF composites. The SEM micrographs of tensile fracture surfaces for the chemical modified composites indicated interfacial interaction and adhesion between WHF and LDPE/NR blends have been improved. The SEM microghaphs of NaOH and EED modified WHF exhibited a rough surface for better adhesion. The PANI modified LDPE/NR/WHF composites exhibited higher conductivity but lower capacity. The FTIR spectra of compatibilized composites and PMMA modified LDPE/NR/WHF composites showed a formation of ester bond while PANI modified LDPE/NR/WHF composites and EED modified LDPE/NR/WHF composites showed the presence of C-N group.