Investigation On Dielectric And Sound Absorption Properties Of Banana Fibers Reinforced Epoxy Composites

This research work focused on the development of banana fiber reinforced epoxy resin composites for dielectric and sound absorption applications. The dielectric and sound absorption properties of the composites were studied with respect to the fiber loading and treatment. The fibers were treated using 5wt % of sodium hydroxide at room temperature. The properties of the composites were measured using HP Impedance Analyzer E4980A and two-microphone transfer function impedance tube method according to the American Society for Testing Materials (ASTM D150-11 and ASTM E1050-12) standards. In general, the composites displayed higher dielectric constant and sound absorption coefficients at the higher fiber loading. In extend, the treated fibers reinforced composites showed higher sound absorption coefficients, but lower dielectric constant values

Fundamental study on the effect of alkaline treatment on natural fibers structures and behaviors

In composites, chemical treatment caused better adhesion interface between fibers and polymer. Thus, in this research, alkaline treatment was performed on jute and kenaf fibers in an alkaline solution containing 5wt % sodium hydroxide diluted with distilled water, at room temperature for 30 minutes. The pH levels of the alkaline solution were maintained approximately at pH 11 to pH 12. The untreated and treated fibers were analyzed using Fourier transform infrared (FTIR) spectroscopy in the range of 4000 cm-1 to 400 cm-1. It is found out that change in the structure and the removal of outer cell layers, cellulose, hemicellulose, lignin, waxes and other impurities during the alkaline treatment that affected the improvement on the adhesion interface between fibers and polymer

Nano-reinforcement in sustainable polymer composites

In this chapter, nano-reinforcement in sustainable composites is highlighted by understanding the different types of nonrenewable and renewable nano-reinforcements and its applications in polymer composites. Most of the known nano-reinforcement for nonrenewable are unbiodegradable, expensive, and unsustainable, while the alternative nano-reinforcement for renewable are biodegradable, cheap, and sustainable. Determining the relationship and characteristic of nonrenewable nano-reinforcement may help improve distinctive properties of the materials, in terms of mechanical, morphological, thermal, etc. Therefore understanding the basic properties of the nano-reinforcement helps determining the area of suitable applications

Sound absorption and impedance study of lignocellulosic fibre based composites for acoustical applications

This study investigates five types of lignocellulosic fibres reinforced polymer matrix composites to be applied for the acoustical material component. In this work, three thermoplastic binders were used, which include polypropylene (PP), poly lactic acid (PLA) and zein. The two thermoset binders used were epoxy and unsaturated polyester. The five lignocellulosic fibres include rice straw, luffa, sisal, oil palm empty fruit bunch, and betel nut. The weight percentage of fibres used ranged from 5 wt.% to 30 wt.%. Hot compression moulding was used in the preparation of specimens for thermoplastic composites. The cold compression process was used in preparation of specimen for thermoset binders. Chemical and physical surface modifications were carried out on natural fibres to enhance the interfacial adhesion between the fibres and the matrix. In this work, sodium hydroxide and heat treatment were used to modify the hydrophilic properties of natural fibres. The effects of this surface modification on the sound absorption, mechanical, and dielectric properties of the composites were measured. Two units of two-microphone transfer function impedance tube devices were fabricated in the laboratory, according to the American Society for Testing Materials, ASTM E1050-12. The first unit was used to measure sound absorption coefficients in the frequency range of 500 Hz to 2000 Hz. The second unit was used to measure the frequency ranging from of 2000 Hz to 6000 Hz. Later, the results from both units were combined to obtain the sound absorption coefficient (α) for the frequency range between 500 Hz to 6000 Hz. Prior to the measurements, a relative calibration of microphone pairs was performed according to ASTM E1050-12 standards. The structural and thermal decomposition of the fibres and their reinforced composites before and after surface treatments were investigated through fibre morphology analysis (scanning electron microscope (SEM)), Fourier transform infrared spectroscopy (FTIR) analysis, and thermo-gravimetric analysis (TGA). Generally for all the composites tested, the composites made of treated fibre had higher sound absorption coefficients than the untreated fibre composites. Increase in fibre content generally leads to higher sound absorption coefficients, with exceptions at certain frequencies. A slight difference in sound absorption coefficients was observed among the five types of composites tested. In these tested composites, the sound absorption coefficients of rice straw/PP composites were found to be the highest. Generally for all the composites tested, the dielectric constant, dissipation factor and loss factor of composites increased with fibre content for the entire range of frequencies. This increase was high at low frequencies, low at medium frequencies, and very low at high frequencies. The dielectric constant, decreased with frequency due to the decreased interfacial and orientation polarization at higher frequencies. The fibre surface modifications by alkaline and heat treatments improves the fibre matrix adhesion, which in turn improves the mechanical properties of composites until the optimum wt.% of fibre. These results were confirmed through SEM and FTIR analysis. After surface modifications, the SEM characterisation showed that the surface modifications changed the morphology of fibres, resulting in the increase of sound absorption coefficients of composites. For all the fibres tested, FTIR spectra confirmed that the shifts in the functional groups that occurred were a result of surface treatments. These shifts show the effectiveness of treatments on the fibres. The TGA thermographs for all the five composites tested have been observed with a slight difference in decomposition temperatures. Thermo-gravimetric analysis revealed that moisture absorbed by the natural fibres was primarily due to the presence of hemicellulose. Hemicellulose also exhibited lower thermal stability compared to cellulose and lignin constituents. Thermal analysis revealed that, the presence of hemicellulose constituents in the untreated fibres had lower thermal stability. Cellulose showed higher decomposition temperatures compared to lignin. Lignin decomposed over a broad temperature range. Treated fibre composites showed higher thermal decomposition temperatures compared to the thermal decomposition temperatures of the untreated fibre composites

Sound Absorption Coefficients Natural Fibre Reinforced Composites

In this Investigation, the influence of two kind of polymers (Urea-formaldehyde and Polypropylene) mixed with natural fibre (Kenaf) were studied for their sound absorption coefficients. Four samples were made; Samples A1 and A2 are made of Kenaf core fibre with adhesive of high emission Urea-formaldehyde resin (HN 100) with 51.6 % solid content. The fabrication of the particle board was done using a hot press for 6 minutes under the pressure of 40 Ton at 1800C for different fibre lengths 1 mm (Sample A1) and 0.6 mm (Sample A2) with weight fraction of 80%. Sample B1 and B2 are made of Kenaf core fibre with polypropylene matrix materials with coupling agent of polyvinyl alcohol. The fabrication of the sample was done using hot press for 30 minutes under the pressure of 1000 Psi at 1800C for different lengths of 1 mm (Sample B1) and 0.6 mm (Sample B2) with weight fraction of 20%. The sound absorption coefficients of samples were measured according to American society for Testing Materials (ASTM E1050 10) two microphone method. It is evident that type of polymer influences the sound absorption coefficients

Experimental determination of Sound Absorption Coefficients of Four types of Malaysian Wood

Currently, one of the important topics in acoustic science is noise control. It is important to control the noise in order to minimize extraneous noise in rooms, buildings, and our environment. Noise control can be achieved by reducing the intensity of sound to the level that is not harmful to human ear. There are four basic principles employed to reduce noise which is absorption, isolation, vibration isolation, and vibration damping. In fact, the most recognized technique to reduce noise is sound absorption on the materials itself. Sound absorption on material such as wood and porous material have been developed and studied by few researchers. Materials that reduce the sound intensity as the sound wave passes through it by the phenomenon of absorption are called sound absorptive materials. There are lot of methods can be used on determining the sound absorption coefficient of materials. In this paper, a preliminary work has been carried out experimentally to determine the sound absorption coefficient of four types of Malaysian wood. They are Tapang (Koompassia excels), Pulai (Alstonai angustiloba), Selunsor merah (Tristianiopsis beccariana) and Jelutong (Dyera polyphylla). The test was performed using the ASTM E1050-98/ISO 10534-2 (American Society for Testing and Material) standards for the sound absorption coefficient testing. This method is known as impedance tube method (Two- Microphone Method). The absorption coefficient depends on the frequencies. In this study the values of the frequencies used was in the range from 350 Hz to 1000 Hz

Processing and Characterization of Banana Fiber/Epoxy Composites: Effect of Alkaline Treatment

This research focuses on the development of natural fibers reinforced polymer matrix composites using agricultural waste, such as banana fibers. The banana fibers were obtained from agricultural field after banana fruit has been matured. And it underwent an alkaline treatment using 5wt% of sodium hydroxide. The composites were prepared with various fiber loadings, ranging from 5wt%, to 20wt%. The effects of alkaline treatment on the mechanical, morphological, and spectral properties were investigated and evaluated using, universal testing machine, light/optical microscope, scanning electron microscopy, and Fourier transform infrared spectroscopy. Based on the results obtained, it is noticed that a lot of factors involved in affecting the characteristics of the natural composites, such as density, fiber amount, structure agglomeration and etc. From the results obtained, treated fiber composites have superior properties as compared with untreated fiber composites

S1E04 - Talking About Authentic Engineering Assessments with Socio-Environmental Impact

An Authentic Engineering Assessment in Sarawak gives students the opportunity to enhance their research skills and explore the socio-environmental impacts that engineering decisions have on local communities. In this podcast, Course Coordinator Dr. Elammaran Jayamani (Sarawak) and his student Haripratshanth Palani Velayda Shanmugasundram reflect on their experience of an authentic assessment which sees students propose sustainable energy sources for small regional communities

Design and simulation of multilayer hybrid foam material for acoustic application

New acoustic multilayer absorber fabricated by coupling closed-cell metallic foam and open-cell polymeric foam, which aimed to develop a practical use of metallic foam in the noise control application. In prior, the individual sound absorption coefficient of both foam materials with different thicknesses measured by the impedance tube method as per ASTM E-1050. Using inverse characterization technique, the intrinsic properties needed for five parameter models in a numerical study are predicted. The measured characteristic impedance, complex wave propagation, and sound absorption coefficient of the individual foams are in close agreement with the prediction. Subsequently, a different configuration of multilayer absorber is modeled using obtained properties, and their acoustic performance is evaluated. The result indicates that the coupling of polymeric foam with metallic one exhibits enhanced sound absorption and usage of closed-cell metallic foam in noise control material. Furthermore, the result demonstrates that absorption capability entirely relies on the placement of polymeric foam in the configuration. The proposed hybrid multilayer absorber coupled with test bench car for interior acoustic study, where 5–30 dB is reduction is noticed in 1/3rd octave plot