Effect of Alkali Treatment Using Calcium Hydroxide and the Fiber Length on the Strength of Sugarcane Bagasse Fibers-Polypropylene Composites

Abstract

Milling sugarcanes to produce sugar generates by-product called bagasse. Due to the large availability and low cost, the potential of obtaining renewable and biodegradable fibers from bagasse had been explored. To produce fibers from these bagasse, the bagasse was treated in alkali solution using 14 % v/v calcium hydroxide, Ca(OH) 2 at high temperature (60-70 o C) for 4 hours. After treatment and washed to remove dissolved substances, the fibers were cut into 3 and 5 cm length. Some fibers were prepared in their original length. These fibers were mixed with polypropylene (PP) matrix in weight % ratios of bagasse fibers/PP 20/80, 25/75, and 30/70 and hotpressed to make composite samples. Composites produced were characterised with tensile test to evaluate their tensile properties. Scanning electron microscopy (SEM) was performed on the fiber surface as well as on the fracture area of the tensile tested samples. Tensile strength of the composite shows an increase with the increase of the fiber length and weight % ratios of bagasse fibers/PP up to 25/75 and decreases when bagasse fibers were added to 30 wt.%. The highest strength of 11,30 MPa was obtained when 5 cm fibers were used in a weight % ratio of bagasse fibers/PP at 25/75. SEM study found a greater number of fibers oriented perpendicular to the tension direction.

The use of sugarcane bagasse in PP matrix composites: A comparative study of bagasse treatment using calcium hydroxide and sodium hydroxide on composite strength

“…There is an indication of carbonate peaks in the range of 1500-1400 and 872 cm -1 which was only found in the fibers treated with Ca(OH)2 solution (Fig.1b). [9] This finding is further supported by Fig. 2(c) presenting scanning electron micrograph taken on the fiber surface after treatment.…”

“…Two different alkaline solutions, NaOH and Ca(OH)2 were used. The results from Ca(OH)2 treatment has been reported elsewhere [9] and a comparative study on composite strength affected from those two different solutions on bagasse fibers was performed in this current study.…”

“…[11,12] That band was absent in fibers after alkali treatment using both solutions which explains a hemicelullose fraction removed in each treatment. [9] The relative absorbance of the primary and secondary peaks of OH groups at 1051 cm -1 and 1165 cm -1 of bagasse fibers treated with NaOH is higher than the ones treated using Ca(OH)2 as shown in Fig. 1(b).…”

“…The spectra 1250cm-1 which is aligninspectrumwas no longerfound insugar canefibersthat have been givenalkalitreatment. [9] Lignin is an amorphous phenolic macromolecule and has the least water sorption of the natural fiber components. [13] The removal of lignin during treatment was favorable to improve interfacial bonding between fibers and matrix.…”

“…This deposit originated from the Ca(OH)2 solution used which contained CaCO3 which has also been identified during EDX analysis. [9] Figures 3 and 4 show the results from the thickness measurement on composite samples with the bagasse fibers treated in Ca(OH)2 and NaOH solution respectively. The measurement was done on tensile test samples using micrometer before test was performed.…”