Processing and Characterization of Epoxy/Luffa Composites: Investigation on Chemical Treatment of Fibers on Mechanical and Acoustical Properties

Abstract

This study focuses on the development of epoxy/luffa composites and the investigation of their mechanical and acoustical properties. The fibers underwent an alkalization treatment, and its effects on the mechanical and sound absorption properties of the composites were measured utilizing a universal testing machine and two-microphone transfer function impedance tube methods. The effects of chemical modifications on the fibers were studied using a scanning electron microscope (SEM). The thermal analyses of composites were conducted using thermo-gravimetric analysis (TGA). The composite's functional group was identified and evaluated using Fourier transform infrared spectroscopy (FTIR). The sound absorption coefficient of untreated and treated composites across a range of frequencies was very similar. Untreated composites appeared to perform better than those that were treated. Compared with untreated fiber composites, there was an improvement in the tensile strength of the treated fiber composites. The SEM characterization showed that the alkaline treatment changed the morphology of the fibers, resulting in a decrease in the sound absorption coefficients of the composites. The thermal characterization of composites showed that dehydration and degradation of lignin occurred in a temperature range of 40 to 260 °C, and the maximum percentage of cellulose was found to decompose at 380 °C.

Windmill Palm Fiber/Polyvinyl Alcohol Coated Nonwoven Mats with Sound Absorption Characteristics

“…Improvements in absorption coefficients at all frequencies, especially at low frequencies of approximately 80 to 2000 Hz, were observed as the thickness of the nonwoven materials was increased. Yang et al (2003) and Jayamani et al (2014) observed an interesting decrease and increase of sound absorption coefficient at a specific frequency for the rice straw (1000 Hz), while for the luffa the corresponding value was 3100 Hz. This kind of decrease and increase was due to the specific characteristics of natural fibers reflecting sound at the specific frequency, but absorbing sound in the middle and high frequency ranges (Yang et al 2003).…”

“…At lower concentration, PVA covers the fibers, the pores between the fibers are maintained and the porosity of each constituent remains open. But at higher concentration, the PVA creates a thin layer around the particles and obstructs the intra-fiber pores (Gle et al 2011;Jayamani et al 2014). As a result, a decrease in the acoustic properties was observed when the PVA concentration was 1.5 wt.%.…”

“…The exothermic peaks of these specimens were quite similar; however, they were slightly higher for sample 9. The high thermal stability of coated nonwoven mats is due to the interaction between the binder and the fiber, which produces additional intermolecular bonding (Jayamani et al 2014). The third stage is the decomposition of lignin and PVA (Ishak et al 2012;Saini et al 2015).…”

“…Lignin is the most difficult to decompose compared to hemicelluloses and cellulose from 160 °C to as high as 900 °C (Ishak et al 2012;Chen et al 2014). The thermal changes indirectly affected the sound absorption properties of the nonwoven mats by changing the expansion of airflow size and porosity inside the natural mats (Jayamani et al 2014). …”

“…Windmill palm fibers (WPFs) are one of the natural fibers that have not been widely used; date palm fibers and oil palm fibers have been studied more. Most of these materials can be used as a reinforcing phase in polymers to prepare composites (Sreekala et al 2002;Alawar et al 2009;Sbiai et al 2010;Alam et al 2012;Shalwan andYousif 2014 andJayamani et al 2014). Because there is very limited research on WPFs, their use as an acoustic material has hardly been discussed.…”