Nazire Deniz Yilmaz

Bio: Nazire Deniz Yilmaz is an academic researcher from Pamukkale University. The author has contributed to research in topics: Fiber & Husk. The author has an hindex of 11, co-authored 26 publications receiving 355 citations. Previous affiliations of Nazire Deniz Yilmaz include Anadolu University.

Effects of porosity, fiber size, and layering sequence on sound absorption performance of needle-punched nonwovens

Abstract: The relationships between the material parameters, i.e., the fiber fineness, porosity, areal density, layering sequence, and airflow resistivity with the normal- incidence sound absorption coefficient of nonwoven com- posites consisting of three layers have been studied. The monofiber or multifiber needle-punched nonwovens included poly(lactic acid) (PLA), polypropylene (PP), glass fiber, and hemp fibers. Air flow resistivity was statistically modeled and was found to increase with decreasing fiber size and nonwoven porosity. The former models devel- oped for glass fiber mats in the literature were found to be inconsistent with the air flow resistance of the nonwovens reported below. The effects of the layering sequence on air flow resistivity and sound absorption were obtained. It was found that when the layer including reinforcement fibers, i.e., hemp or glass fiber, faced the air flow/sound source, the air flow resistance and the absorption coeffi- cient were higher than the case when the layer including reinforcement fibers was farthest from the air flow/sound source. The difference was more pronounced if there was a greater difference between the resistivity values of the constituent layers of the nonwoven composite. Sound absorption coefficient was statistically modeled in terms of air flow resistivity and frequency. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 3056-3069, 2011

Hemp-fiber based nonwoven composites: Effects of alkalization on sound absorption performance

Abstract: The effects of the material and treatment parameters on airflow resistivity and normal-incidence sound absorption coefficient of alkalized three layered nonwoven composites have been studied. The material parameters included fiber size and porosity. The treatment factors included the temperature, duration and concentration. The alkalized composite was a three-layered nonwoven sandwich structure consisting layers of Polypropylene/Hemp/Polypropylene. Alkalization treatment has been found to result in a loss of basis weight and a decrease in air flow resistivity. Among treatment factors, only temperature was found to be a statistically-significant factor on air flow resistivity. Higher-temperature alkalization leads to higher air flow resistivity compared to the lower-temperature treatment. Alkalization at higher temperature and higher concentrations gives better results in normalized sound absorption performance compared to lower-temperature and lower-concentration treatments, respectively.

Multi-fiber needle-punched nonwoven composites: Effects of heat treatment on sound absorption performance:

Abstract: Nonwovens have been increasingly used in car interiors for noise reduction. Most of these nonwovens are subjected to thermal treatments to give the nonwovens their final three-dimensional forms. Th...

Effects of enzymatic treatments on the mechanical properties of corn husk fibers

Abstract: Corn husk fibers were extracted by water retting, alkalization, and enzymatic processes at different concentration and duration levels. The effects of extraction process parameters on the mechanical and thermal properties and chemical characteristics of corn husk fibers were investigated. Chemical structures of the fibers were studied by IR measurements. The finest and the stiffest fibers were produced by water retting followed by an enzymatic treatment. The highest breaking strength and breaking tenacity were obtained by water-retted fibers. While resulting in loss of breaking tenacity and elongation in water-retted fibers, enzymatic treatment resulted in increase in initial moduli and breaking tenacity of alkalized fibers. No significant effect of enzymatic treatment duration was obtained on the mechanical properties of corn husk fibers. Alkalized fibers gave higher elongation and lower stiffness compared to water-retted ones. The IR spectra showed higher amount of lignin and hemicellulose in water-rett...

Effects of material and treatment parameters on noise-control performance of compressed three-layered multifiber needle-punched nonwovens

Abstract: The effects of material and treatment parameters on airflow resistivity and normal-incidence sound absorption coefficient (NAC) of compressed three-layer nonwoven composites have been studied. Material parameters included fiber size and porosity, and treatment factors included applied pressure and duration of compression. Fibers used included poly(lactic acid) (PLA), polypropylene (PP), glassfiber, and hemp. Three-layered nonwoven composites were classified based on material content and fiber blend. LHL and PGP were sandwiched structures consisting of PLA/Hemp/PLA and PP/glassfiber/PP layers, respectively. PGI consisted of three layers of an intimate blend of PP and glassfiber. Statistical models were developed to predict air flow resistivity from material parameters and the change in air flow resistivity from compression parameters. Independent variables in the first model were porosity and fiber size and, in the latter model, were compressibility, pressure, and initial material parameters. An increase in air flow resistivity was found with increased compression. No significant effect of compression duration was detected. Two additional statistical models were developed for the prediction of sound absorption coefficient based on material and treatment parameters. The independent variables of the first model were air flow resistivity, thickness, and frequency, and those of the second model were compressibility, initial thickness, and initial density of the composite, diameter and density of the fiber, compression pressure, and frequency. A decrease in sound absorption coefficient was detected with increasing compression, while no effect of duration was detected. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Acoustic energy absorption properties of fibrous materials: A review

Abstract: Fibrous materials have been widely used in noise reduction due to the porous structures. In this review, available studies regarding the prediction methods of acoustic absorption coefficient are gathered. Empirical model could predict the acoustic absorption coefficient based on facile airflow resistivity, while microstructural model is determined by detailed structural parameters of fibrous materials. Various fibrous materials including inorganic and metallic fibers, synthetic fibers, natural fibers, and nanofibrous membranes for noise reduction are reviewed. Inorganic and metallic fibers have the advantages of corrosion resistance, high temperature resistance and long service life. The tailored cross-sections of synthetic fibers such as circle, hollow and triangle are beneficial to improve acoustic absorption properties. Natural fibrous materials are biodegradable, renewable and eco-friendly. Nanofibrous materials are lightweight and have good potential in low frequency noise reduction. Herein, we summarized the recent advances concerning the acoustic absorption of various fibrous materials.

Physical and mechanical properties of natural fibers

Abstract: With the increase of crude oil prices, environmental concerns and growing global waste problems drive the interest on sustainable and eco-friendly products, including natural fibers, as an alternative to materials derived from petroleum or nonrenewable sources. Natural fiber belongs to the earliest known cultivated plants, which have intrinsic properties: low weight, cost, high specific strength, and specific stiffness. These properties have made them particularly attractive to many and varied industrial uses. The factors that should be considered in using natural fibers are safety, mechanical strength, and stiffness improvement of the composites, decreasing the density and environmental issues. This chapter intends to describe the physical and mechanical properties of natural origin fiber fabrics. Also, this chapter is going to study the reinforcing capabilities of natural fiber in different composites. Here, some challenges due to poor compatibility between the fibers and the matrix from a bonding strength point of view will be discussed.

An overview on corporate response towards sustainability issues in textile industry

Abstract: Textiles constitute an important part of human beings everyday life. Environmentalists have been calling forth industries to incorporate sustainability principles into their production processes. In comparison with other industries, textile industry is considered to be major contributor towards environmental pollution and is subject to creating various ecological (water body pollution, waste generation, air pollution) issues throughout supply chain from fibre production till fabric finishing. This paper reviews the existing literature related to various sustainability issues surrounding the textile industry across the globe. The authors classify the literature to discuss the drivers, barriers, and responses of firms in the textile industry in favour of sustainability. Despite a growing body of research in this area, we identify significant gaps in the literature with special reference to managerial approaches being used for incorporating sustainability. While it is very important to understand the motivations that drive firms towards sustainability and barriers to implementation, attention is also drawn towards research aspects pertaining to managerial perception towards new technologies and processes. The article also provides future research opportunities in form of specific questions to strengthen existing literature in this field.

Highly compressible and anisotropic lamellar ceramic sponges with superior thermal insulation and acoustic absorption performances.

Abstract: Advanced ceramic sponge materials with temperature-invariant high compressibility are urgently needed as thermal insulators, energy absorbers, catalyst carriers, and high temperature air filters. However, the application of ceramic sponge materials is severely limited due to their complex preparation process. Here, we present a facile method for large-scale fabrication of highly compressible, temperature resistant SiO2-Al2O3 composite ceramic sponges by blow spinning and subsequent calcination. We successfully produce anisotropic lamellar ceramic sponges with numerous stacked microfiber layers and density as low as 10 mg cm−3. The anisotropic lamellar ceramic sponges exhibit high compression fatigue resistance, strain-independent zero Poisson’s ratio, robust fire resistance, temperature-invariant compression resilience from −196 to 1000 °C, and excellent thermal insulation with a thermal conductivity as low as 0.034 W m−1 K−1. In addition, the lamellar structure also endows the ceramic sponges with excellent sound absorption properties, representing a promising alternative to existing thermal insulation and acoustic absorption materials. Temperature-invariant highly compressible ceramic sponges are attractive for thermal insulators and energy absorbers, but development is limited by complex preparation processes. Here the authors report large-scale fabrication of silica-alumina composite ceramic sponges via blow spinning and calcination.