CHAPTER 9 SUMMARY AND CONCLUSION

Transcription

1 125 CHAPTER 9 SUMMARY AND CONCLUSION 9.1 SUMMARY The acoustic characteristics of a room or a auditorium can be controlled by covering the walls, ceiling and floor with materials having suitable acoustic absorptive characteristics. Nonwoven is a kind of material with orientation and random arrangement of fibers bonded by means of thermal and chemical are very much suitable for the application as sound absorbing materials. The reclaimed fibers of nonwovens of cotton, polyester and cotton polyester blend which were developed into 12 distinct samples and 9 nonwoven composite samples. Through this research work the samples were tested and analyzed for their physical and acoustical characteristics. The sound absorption character is different from the sound resistance character of a material. Hence a sound insulation tester has been used to measure sound resisting capacity of the nonwoven composite materials. The reclaimed fibers of the cotton, polyester and cotton polyester blend of colour and white were developed. The thermal and chemical bonded sound absorption nonwovens and composite material has been developed and

2 126 tested for the physical, acoustical and sound insulating characteristics of the samples have been tested. Among them the thermal bonded nonwovens with colour cotton/polyester nonwoven showed higher acoustic performance of 24% and the sample of colour cotton/polyester showed higher insulating value of 16.7% at 75cm distance from the source. Hence, it is recommended that the above two sample specification and process parameters were suitable for better sound absorption and sound resistance applications. The chemical bonded nonwovens with colour cotton/polyester nonwoven showed higher acoustic performance of 37% and the sample of colour cotton/polyester showed higher insulating value of 12.3% at 75cm distance from the source. Hence, it is recommended that the above two sample specification and process parameters were suitable for better sound absorption and sound resistance applications. The composite with thermal & chemical colour cotton/polyester sample shows the high air flow resistivity with the value of 19.5% which influence the high increase in air flow resistance. It also has the acoustic performance of 45%, hence the above sample is recommended for the better sound absorption and sound resistance applications. 9.2 CONCLUSIONS Following conclusion were derived from this research work i) Soft waste and hard waste from spinning process, weaving and knitting waste are the major classification of the textile waste. In

3 127 this study knitted process fabric waste of white and colour have been used as the raw material. ii) -used -used fabric opener process is similar to that of textile carding process where fibers in the grip of metallic teeth on the surface of a drum are dragged through the teeth of other surfaces. This trial was designed to study the problems inherent in breaking down the fabric remnants into smaller pieces and ultimately into reclaimed fibers. This involves passing cut fabric pieces through two nipped feed rollers that grip the textile while a rapidly rotating cylinder covered in sharp metallic pins mechanically opens the fabric into smaller fractions. The reclaimed fibers are then collected on a vacuum assisted drum and fed out of the machine. iii) Based on the fiber characteristics evaluated, it can be concluded that the fibers may be easily changed into nonwovens. The recycled fiber nonwoven exhibits higher efficiency of sound absorption due to the following factors: effect of fiber diameter, shortened length of fibers, and variable pore geometry of the fabric. iv) The reclaimed fiber of thermal bonded nonwoven sound absorbing materials were developed by using the fibers recycled

4 128 from the waste of cotton, polyester and cotton polyester blend were taken. In total there were 6 samples of cotton colour and white, polyester colour and white and cotton/polyester colour and white have been produced. Among 6 samples colour cotton/polyester nonwoven showed highest average SAC of v) The sound resistance of thermal bonded nonwoven has been tested using sound decibel meter with different sound level of 30dB to 60dB. The colour cotton/polyester showed higher sound resistance of 60%. This is because the nonwoven fabrics of recycled fibers while increasing the no of layers, the areal density and bulk density also increased and thus resulting in higher sound absorption coefficient. Hence colour polyester, white cotton/polyester and colour cotton/polyester nonwovens at 75cm distance from the source showed the sound insulating values of 37%, 44% and 60% respectively. vi) The 6 samples of chemical bonded nonwoven sound absorbing material were developed. Among the 6 samples colour cotton/polyester showed the highest average SAC of The colour cotton/polyester showed higher sound resistance of 64%. This is because the nonwoven fabrics of recycled fibers while increasing the no of layers, the areal density and bulk density also increased and thus resulting in higher sound absorption coefficient. Hence colour polyester, white cotton/polyester and

5 129 colour cotton/polyester nonwovens at 75cm distance from the source showed the sound insulating values of 43%, 45% and 64% respectively. vii) Totally 9 samples of sound absorbent nonwoven composite materials have been produced. Among them Thermal and Chemical colour cotton/polyester material exibit higher sound absorption co efficient of It can be inferred that, higher airflow resistance always gives better sound absorption values. The value of the air flow resistance of the Thermal and Chemical colour cotton/polyester is 0.84.

6 130 SUGGESTIONS FOR FUTURE WORK In this research work the reclaimed fiber from cotton and polyester of white and colour waste fabrics have been used. Similarly the reclaimed fibers may be produced using other types of fabrics like viscose nylon poly propylene jute flux and wool etc,. The present work focuses on composite material developed from chemical and thermal bonded non wovens. Similarly novel products of coated woven and knitted fabrics of multi layered fabrics of different fibers can be studied further. The acoustic textile materials for home interior and other applications like acoustic resisting material may also be tried with different fibers of woven and knitted multi layered fabrics. Based on the test results obtained different non woven composite material can be recommended for automotive interior products for noise reduction application.