Microstructure and performance characteristics of acoustic insulation materials from post-consumer recycled denim fabrics

Abstract

<jats:p> One of the key issues of the 21<jats:sup>st</jats:sup> century is to reduce the rate of continuously increasing environmental pollution from waste generated by human beings. Use of recycled materials and environmentally friendly approaches to manufacturing can be a good way to deal with these challenges. Similarly, sound pollution has been increasing at an alarming rate due to industrialization and modernization. Use of acoustic insulation materials produced from recycled textile waste can play a vital role in reduction of sound pollution while simultaneously helping reduce municipal solid waste. The goal of this study was to evaluate the recycling of used apparels to produce commercially feasible sustainable products using nonwoven fabrication techniques with a biodegradable thermoplastic binder fiber for possible use as acoustic insulation panels. Recycled denim fibers were used with Sorona® or a PLA binder fiber to successfully produce sound insulation with good performance properties. Maximum transmission loss of about 24 dB and transmission coefficient close to zero at around 1000 Hz were observed. The data indicated that there is a direct correlation between loss of sound transmission with increase in thickness, areal density and decrease in air permeability. When compared with commercially available acoustic insulation material (gypsum board), these products had better insulation properties, indicating that recycled textile products can be used to produce such value-added materials, giving them another useful life before safely disposing in composting environments. </jats:p>

Investigation of sound transmission loss of natural fiber/rubber crumbs composite panels

“…Also, it is important to participate in the economical ways of producing sound-absorbing materials which are cheaper and eco-friendly. 14,29…”

“…33,37,38 The meltblown nonwoven structure has a low areal density, fiber diameter, and average pore diameter resulting in a relatively high coefficient of sound absorption, particularly in the middle-frequency region. 13,14,27 In the case of the multi-layer structure, the STL mainly depends on the sound transmission of the layer directly facing the sound wave. When using a layer of the meltblown fabric over the rubber crumbs/fiber panel and due to the air gap between the two layers, the surface texture of the rubber crumbs is not smooth, therefore keeping air gaps increases the insolation of the panels.…”

“…The measurements are repeated three times with and without sample and results are averaged. STL can be calculated, ASTM E2611, using the following equation 13,14 where A is the incident and C is the transmitted sound components in decibels.

Figure 3.Schematic drawing of the measurement setup. 27

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“…The post-consumer textile waste is suitable to produce commercially feasible sustainable products for acoustic insulation by using nonwoven fabrication techniques in the form of loose fibers, nonwoven fabric, and compostable thermoplastic binder fibers as the insulation materials. 1,[13][14][15] The acoustic absorptivity of nonwoven samples at low, mid, and high frequencies is improved by increasing the thickness of the tested samples, which increases the friction losses. The energy losses elevate with the adding of the air spaces behind the sample at mid and high frequencies.…”

Microstructure and physical properties of composite nonwovens produced by incorporating cotton fibers in elastic spunbond and meltblown webs for medical textiles

“…[32]. The value is larger than most hydroentangled and needle-punched nonwovens [33][34][35]. Thus, the addition of cotton reduced air permeability to some extent in all the cases, and the reduction was dependent on the initial structure and properties of the elastomeric webs.…”