Study on the effects of denier and shapes of polyester fibres on acoustic performance of needle-punched nonwovens with air-gap: comparison of artificial neural network and regression modelling approaches to predict the sound absorption coefficient of nonwovens

In this article, a comparative analysis of artificial neural network (ANN) and regression modelling approaches has been carried out to predict the sound absorption coefficient (SAC) of nonwovens plus air-gap at wide range of frequencies (50–6300?Hz). Needle-punched nonwoven fabrics were produced with different denier and cross-sectional shapes of polyester fibres to study their combined effect on acoustic performance of nonwovens. The surface area of fibres, specific airflow resistance and mean flow pore size of nonwovens were analysed to explain their sound absorption behaviour. Finer fibre nonwovens perform better than the coarser fibre nonwoven as sound absorber. The effective surface areas of fibres in the nonwoven structure greatly affects the SAC. Finer fibres will get aligned easily in z-direction compared to coarser fibres, facilitating formation of more tortuous channels in the fabric structure contributing damping of sound waves. It has been observed that ANN model predicts the SAC with high degree of accuracy than the regression model. The ranking of input parameters in predicting SAC of nonwovens was analysed. Both the models ranked frequency of sound is the major determinant for predicting SAC followed by specific airflow resistance of nonwoven fabric.     

分层复合水刺/热风非织造材料的吸声性能研究

以水刺非织造材料、热熔纤网和热风非织造材料为原料,分层叠加,置于烘箱中热风加热,制得两层和三层复合非织造材料。对分层非织造材料的厚度、透气性、孔隙率以及吸声性能等进行测试,探讨各因素对材料吸声性能的影响。测试结果显示:随着非织造材料厚度增加,同一声波频率的吸声系数提高;单层非织造材料的吸声系数随声音频率的增大而提高;双层复合材料吸声系数随着热风非织造材料面密度增加而提高,最高吸声系数向低频段偏移,吸声频段拓宽,吸声系数随着频率增加呈先上升再下降的趋势;双层分层吸声材料选择孔隙率梯度从受声面开始由低到高排列,三层复合材料的孔隙率按照低—高—低排列,可获得较好的吸声效果。     

SiO2气凝胶/聚酯-聚乙烯双组分纤维复合保暖材料的制备及其性能

为开发综合性能优异的复合保暖非织造材料,以聚酯-聚乙烯(PET-PE)双组分皮芯结构复合纤维为主体,通过热风工艺,采用自然沉降法使SiO₂气凝胶粉末粘附于复合纤维表面,制得SiO₂气凝胶/聚酯-聚乙烯纤维复合非织造材料。对复合非织造材料表面SiO₂气凝胶粉末质量分数、微观结构、保暖性能、压缩回弹性能、拉伸性能、透气性能进行测试与分析。结果表明:SiO₂气凝胶粉末与聚酯-聚乙烯复合纤维可有效结合,SiO₂气凝胶粉末的加入对纤维网具有一定的支撑作用,提升了复合非织造材料的压缩回弹性能、拉伸性能,同时因增加了纤维间静止空气的含量,使复合非织造材料的保暖性能得到提升。     

Sound and thermal insulation properties of flax/low melt PET needle punched nonwovens

Noise pollution is an ever increasing problem in the world because of the industrial revolution. Recently, researchers have begun investigating natural fiber composites as potential materials for the manufacture of sound absorption structures. In this work, flax/low melting point polyester needle punched nonwoven fabrics were manufactured and characterized for sound and thermal insulation applications. Nonwovens were developed by blending flax fibers with low melt PET at three blend ratios (10%, 20%, and 30%) with 7 mm and 10 mm needle penetration depth. The test results showed that there was a decrease in thermal resistance value with increase in low melt PET % and needle penetration depth. The developed nonwovens had better sound insulation value at medium and high frequency. There was no significant change in sound insulation value with increase in low melt PET %.     

双层复合非织造材料基吸声体吸声性能研究

以熔喷丙纶非织造材料和玻璃纤维水刺非织造材料为受声面和背衬层,通过热粘合方式制成双层复合非织造材料基吸声体。通过分析吸声体受声面和背衬层非织造材料的厚度、面密度、孔径、孔隙率等结构参数与复合吸声体的吸声系数之间的关系,探讨各层非织造材料结构参数对复合吸声体吸声性能的影响。实验结果表明,随着熔喷丙纶非织造材料和玻璃纤维水刺非织造材料厚度和面密度的增加,吸声体中高频段吸声系数显著提高;受声面和背衬层的孔径尺寸和孔隙率的变化对双层复合非织造材料基吸声体的吸声性能影响较为显著。     

Development of acoustic nonwoven materials from kapok and milkweed fibres

Acoustic properties of textile materials have been studied for several decades. But, mostly used materials were synthetic, and hence, they were not eco-friendly in nature. Therefore, an attempt was put forward to try the sound absorption property of natural fibres and their blends by needle-punched nonwoven techniques. Nonwoven fabrics of ideal materials are used as acoustical insulation products because they have high total surface area. The effect of blend proportion of kapok and milkweed fibres with cotton, fabric GSM, bulk density and distance of fabric from sound source on sound reduction of nonwoven fabrics was investigated. The sound reduction increases with increase in blend proportion of kapok and milkweed fibres. A nonwoven fabric of cotton/milkweed 40/60 shows the highest sound reduction potential. As the distance between the fabric and sound sources increases, the sound reduction also increases linearly due to reduction of sound intensity which reduces the transmission of sound through the fabric. There is a positive correlation between fabric GSM and sound reduction and negative correlation between bulk density and sound reduction. Further, the thermal conductivity of nonwoven samples decreases with increase in kapok and milkweed blend proportion due to increase in thickness of samples. Hence, the kapok- and milkweed-blended nonwoven samples provide sound as well as thermal insulation characteristics.     

结构参数对非织造材料吸声系数的影响

分别以涤纶针刺法非织造材料和丙纶熔喷非织造材料为基,通过热粘合方式制成不同参数的同质非织造材料吸声体。通过分析同质非织造材料吸声体的厚度、面密度、孔径、孔隙率等结构参数与其平均吸声系数之间的关系,探讨非织造材料结构参数对其吸声性能的影响。实验结果表明,对于同种材料而言,涤纶针刺非织造材料与丙纶熔喷非织造材料的结构参数对其平均吸声系数具有较大影响,材料的平均吸声系数随厚度和面密度的增加而增加。     

木棉及其混合纤维非织造材料吸声预测模型

以Allard模型为基础,采用等效流体的方法,拟建立一个能够准确描述木棉及其混合纤维非织造材料吸声行为的吸声模型。该模型结合木棉纤维的大中空结构,考虑了材料的热传导效应及纤维框架的柔软性。使用新建立的吸声模型及Allard模型分别对4种不同结构的木棉纤维非织造材料的吸声系数及比表面阻抗进行了计算,并将计算值与实验样品的测量值进行比较。结果表明:新模型的计算结果更接近实验值,说明新模型更适用于木棉及其混合纤维非织造材料吸声性能的预测,为工业产品的设计提供了理论参考。     

Recycling of cotton and polyester fibers to produce nonwoven fabric for functional sound absorption material

Recycled fibers are commonly used in dissimilar applications and one of the most important applications is sound absorption. Recycled fiber nonwovens currently are in greater demands in industries because of their advantages such as low cost, biodegradability, acceptable mechanical and physical properties, and so on. Sound absorption materials, renewable, and eco-friendly nonwovens have been developed using recycled cotton and polyester fibers. This research provides a contribution to the body of knowledge on the sound absorption properties of nonwovens using recycled fibers which contain cotton and polyester by means of spun-laid technique and provides a better understanding of the effects of a number of manufacturing processes on nonwovens noise control performance and also contributes to the wider adoption of nonwovens as sound absorbers. The sound absorption coefficients were measured according to ASTM E 1050 by an impedance tube method. The results revealed that the average of the sound absorption coefficients increased with the thickness of the nonwovens, but decreased with the nonwoven fabric density.     

Effect of compressibility on heat transport phenomena in aerogel-treated nonwoven fabrics

The heat transport properties observed in nanostructured materials such as aerogel-treated nonwoven fabrics are promoting revolutionary breakthroughs as thermal insulators. This article is focused on the thermal transport characteristics of nonwoven fabrics treated with aerogel for potential uses in thermal protective applications. Highly efficient aerogel thermal blankets are now considered a viable option in applications such as clothing, building, and pipelines. A variety of fiber and fabric structures or finishing parameters influence the functional properties of nonwoven materials. In order to assess the thermal properties of aerogel-treated nonwoven fabrics, the KES Thermolabo II and NT-H1 (plate/fabric/plate method for thermal conductivity, q_max cool/warm feeling, and thermal insulation) was used. Fabrics of higher thicknesses show lower heat conductance and therefore higher thermal insulation properties. It has been found that thermal insulation is also related to the weight and compressional properties of the fabric. To make an insulating material effective, it should have low compression set and high resiliency to make the still air to be entrapped into the fibrous material.     

聚酯纺粘非织造布的润湿性和芯吸性的研究及常压等离子体改性

研究了通过热点纺粘法制得的聚酯非织造布的表面润湿性和内部芯吸性,并采用常压等离子体技术有效改善了非织造布表面的亲水性。     

Analysis of acoustic performance of glass fiber felts after water absorption and their estimation results by artificial neural network

Abstract

The acoustic performance of glass fiber felts after water absorption was researched in the paper. The effects of sound frequency and moisture content on the sound transmission loss (STL) and sound absorption coefficient (SAC) were analyzed. In addition, two types of artificial neural networks (ANN) were established to estimate the acoustic performance. In the first ANN model, the sound frequency and moisture content were chosen as input parameters to predict the STL and SAC values. In another model, the output parameters were replaced by the ratios of STL and SAC to areal density. In order to evaluate the accuracy of the two models, the mean relative error and correlation coefficient were calculated respectively. It has been proved that the predicted values resulted from ANN models fit well with the measured values.     

Acoustic performance of woven fabrics in relation to structural parameters and air permeability

This work deals with the study of the acoustic characteristics of woven fabrics in relation to fabric structural parameters and air permeability. In order to achieve the objectives of the research, sound absorption coefficient of woven fabric samples was determined via impedance tube method. Samples with various pick densities and yarn twist were used. The effect of fabric thickness was analyzed using three and six layered test samples. Results showed that, while for all samples the minimum values of sound absorption were observed at frequency bands of 250 and 2000?Hz, the maximum sound absorption occurred at the frequency of 1000?Hz. Results also indicated that fabrics woven at pick density of 30?thread/cm exhibited higher sound absorption than fabrics woven at other pick densities. It was found that, noise reduction coefficient of three and six layered samples, woven at low pick densities showed significant increases in comparison to those woven at high pick densities. It was also established that samples woven with lower weft yarn twist absorb sound wave more efficiently. It was concluded that fabric air permeability can be used as a criterion of sound absorption behavior of woven fabrics.     

Basis weight uniformity analysis in nonwovens

It is widely recognized that nonwoven basis weight uniformity affects various properties of nonwovens, including appearance, physical properties, or mechanical properties. However, it is one of the nonwoven characteristics that is most difficult to characterize. This paper reports on the methodology based on the well-known quadrant method that objectively quantifies uniformity of nonwoven fabrics.     

Investigations on Sound Absorption Properties of Luffa Fibrous Mats

In this study, the natural fibrous mats were developed using luffa fibrous materials and their sound absorption properties were investigated. Kapok/cotton web was used as middle layer in between two mats in order to improve the sound absorption efficiency. Four fibrous mats with different composition of layers were developed using thermal bonding. The developed mats were tested for Noise Reduction Coefficient (NRC) as per ASTM E 1050. The parameters influencing sound absorption properties of the developed mats such as addition of kapok/cotton web on the mats, thickness of mats and air gap maintained in the impedance tube during testing have been investigated. The sound absorption properties of developed mats improved due to the addition of kapok/cotton web and increased air gap. The increase in thickness of mats resulted in increase in sound absorption properties. Luffa mats having 4 layers had NRC value of 0.39 at the frequency range of 250 Hz to 2000 Hz which is comparable with commercially available glass fiber board.     

SiO2气凝胶/芳纶非织造布复合织物的防护功能

为研究SiO₂气凝胶对芳纶非织造布抗压、阻燃防护功能的影响,以芳纶非织造布为骨架材料,将SiO₂气凝胶施加到芳纶非织造布表面,制备出SiO₂气凝胶混杂芳纶非织造布防护材料。通过扫描电子显微镜对其结构形貌进行表征,借助万能材料试验机对其抗压性能进行分析,最后利用热常数分析仪和火焰手系统,测试并评估了制备的防护材料的阻燃隔热性能。结果表明:SiO₂气凝胶以不同大小的块状、颗粒状填充进入芳纶非织造布纤维间的空隙;SiO₂气凝胶可增强芳纶非织造布的抗压性能,且降低其导热系数;混杂SiO₂气凝胶后芳纶非织造布总的吸收能量值降低,说明SiO₂气凝胶可明显增强芳纶非织造布的热防护效果。     

吸音纤维材料

综述了吸音机理及其测定方法,举例说明了聚酯非织造材料及其边材回用品的吸音特性,建筑用吸音材料对噪音及音响的控制,并介绍了聚酯非织造环保吸音材料.     

CuO/聚丙烯/乙烯-辛烯共聚物复合熔喷非织造材料的制备及其吸油性能

为高效经济地处理油品泄漏引起的污染问题,利用聚丙烯(PP)与乙烯-辛烯共聚物(POE)共混后制备复合熔喷非织造材料,然后在其表面负载纳米氧化铜(CuO)进行疏水改性.对改性前后非织造材料的形貌、结构、水接触角、吸油和力学性能等进行测试.结果 表明:负载纳米CuO后,CuO/PP/POE复合熔喷非织造材料的结晶度下降,熔...     

导电涤纶非织造布的制备及其性能

为开发智能柔性传感器及具有防护功能的金属化导电纺织材料,采用高温无钯活性镍源和化学镀的方法制备涤纶镀镍非织造布。分析了镀覆温度、镀液pH值、镀覆时间、主盐浓度对涤纶非织造布电阻的影响,并测试了镀镍非织造布的导电性、保暖性和抗电磁辐射性能。得到涤纶非织造布化学镀镍最佳工艺:主盐硫酸镍浓度为0.1 mol/L, 镀覆温度为50 ℃,pH值为9,时间为60 min。结果表明:采用最佳工艺制备的镀镍非织造布的方块电阻下降至0.114 Ω/□,导电性能优异;且镀镍后非织造布热阻提高,克罗值增加,传热系数降低,在100~3 000 MHz范围内屏蔽效能增加,具有较好的保暖性和抗电磁辐射性能;涤纶表面镀层致密平整,镀层主要成分为金属镍。     

基于金属有机框架化合物的非织造复合材料制备及其对废水中六价铬的去除

为解决水体中重金属六价铬(Cr(Ⅵ))的污染问题,利用聚氨酯(PU)对锆基金属有机框架化合物(UiO-66-NH2)进行接枝改性,将改性所得PU/UiO-66-NH2负载于聚丙烯(PP)非织造布上制备PU/UiO-66-NH2/PP非织造布复合材料,最后将其用于Cr(Ⅵ)的吸附与可见光催化还原.探讨UiO-66-NH2...