Effects of total surface area and fabric density on the acoustical behavior of traditional thermal‐bonded highloft nonwoven fabrics

Nonwoven fabrics are ideal materials for use in acoustical insulation products because they have a high total surface area, which is directly related to the denier and cross‐sectional shape of the fiber. The smaller the denier, the more fibers for the same material density, the higher the total fiber surface area is. This results in a greater opportunity for interaction between the sound wave and the fibers in the structure. Another important parameter is the density of the nonwoven material, which affects the geometry and the volume of the voids in the structure. The acoustical properties of fabric materials are measured using one of two methods: the impedance tube method and the reverberation room test method. The impedance tube method uses very small test samples (5–15 cm), whereas the reverberation room test method requires large test samples and is expensive to set up. For making comparative analysis of the test samples and overcoming the disadvantages of the current test methods, a direct comparative acoustical properties measurement device has been developed and fabricated in the School of Materials Science and Engineering at Clemson University in an attempt to overcome some of the disadvantages of the other method.     

Determination of the minimum sample size for a reliable strength measurement of talc‐filled polypropylene fibers

Accurate determination of mechanical properties plays an important role to comment on improvement in the mechanical properties of particle‐filled PP fibers. However, the existing standards are not totally suitable for reliable strength determination of particle‐filled PP fibers. In the framework of this study, microsized talc particle‐filled PP fibers were produced with different talc ratio and tensile strength measurements were performed with various gage lengths. Statistical Akaike Information Criterion analysis shows that strength distribution of talc‐filled PP fibers is best characterized by Weibull distribution function. It is reported that, the gage length has almost no influence of Weibull parameters of pure PP fibers while strong effects on Weibull parameters of talc‐filled PP fibers. It is shown that if the tensile strength of talc‐filled PP fibers is to be measured, at least 50 samples, which is more than value suggested by existing standard, should be used for a reliable determination of Weibull parameters. Therefore, the main aim of this study is to question the feasibility of minimum sample size suggested by the existing ASTM D3822 standard for reliable strength measurement of talc filled PP fibers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44083.