Sound Absorption Characteristics Of Spent Tea Leaf Fiber-Rubber Composite Materials

• المؤلف الرئيسي: Wong, Kylie Muh Shin
• التنسيق: أطروحة
• اللغة: الإنجليزية; الإنجليزية
• منشور في: 2017
• الموضوعات: T Technology (General); TA Engineering (General). Civil engineering (General)
• الوصول للمادة أونلاين: http://eprints.utem.edu.my/id/eprint/22409/; https://plh.utem.edu.my/cgi-bin/koha/opac-detail.pl?biblionumber=107368

Sound control has been regarded as one of the important requirements for human comfort. Conventionally, synthetic fibers, such as glass fibers are used as sound absorbing material. It was found that glass fibers present negative impacts in terms of environment ecology and human safety. Glass fibers are non-biodegradable, high in cost and unsafe during handling. Due to these aforementioned disadvantages, natural fibers have recently been gaining attention to substitute synthetic fibers as they offer some advantages including biodegradable, lower greenhouse gas emission, lower density, lower cost and user friendly. This study is intended to demonstrate the feasibility of spent tea leaf fiber (STLF), a type of natural fiber as porous sound absorbing material. STLF is a by-product obtained during the processing of tea leaves at tea plantation industry. Three different grades of STLF are studied and the acoustic property is analyzed in terms of sound absorption coefficient (SAC) and transmission loss. In this study, natural rubber (NR) latex is introduced as binder to hold the fibers in shape, producing an open-pore structure. Impedance tube measurement is performed to analyze the acoustic properties of STLF based sound absorber presented in Phase 1. Phase 2 focused on the effect of fiber grade, binder content and air gap distance on acoustic performance of STLF by using statistical factorial design of experiment. Results show that all the samples obtained maximum SAC above 0.70 at frequency range of 1990-3800 Hz. In addition, it is found that finest STLF with the average diameter of 0.129 mm exhibits better acoustic performance as compared to other two grades STLF. Phase 2 results suggest that fiber grade, binder content and air gap distance have significant effect on the acoustic performance of STLF. It is confirmed through the analysis of variance (ANOVA) test with a confidence interval of 95% in which all three selected factors show P-value < 0.0500. Generally, the sample with smallest diameter fiber grade (0.129 mm) mixed with high binder content (41 wt%), incorporated with air gap distance (30 mm) is able to absorb 98.2% of sound at frequency around 1000 Hz. Lastly, PVC perforated membrane is used as cover screen to protect the STLF. The presence of perforated membrane enhances the acoustic absorption of STLF mixed NR latex by 25.1%. The overall results indicate that STLF can be promising environmental friendly sound absorbing material.