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。     

羊毛及其混合纤维非织造材料的吸声性能

为优化羊毛非织造材料的吸声性能,以羊毛、毛/涤、毛/麻3种纤维制备非织造材料。通过阻抗管对3种非织造材料的吸声性能进行测试,分析了声波频率在250-6 300 Hz范围内,材料的纤维种类、厚度和空腔深度对其吸声性能的影响。结果表明,3种样品的平均吸声系数均大于0.2,纯毛非织造材料的吸声性能略好于毛/涤材料与毛/麻非织造材料;通过增加材料厚度或设置空腔的方式均可提高材料全频段（尤其中低频段）的吸声性能,其中厚度对材料吸声系数的影响程度更大;从环保、材料价格、便于施工等方面考虑,以厚度为6 mm的毛/麻非织造材料作为吸声材料,并设置6 mm的空腔, 即可达到较为优异的低频吸声性能。     

玄武岩包芯织物的制备及吸声性能

针对玄武岩纤维集束性差且可纺可织性低的缺点,使用涤棉纤维与玄武岩纤维制备3种线密度的赛络包芯纱线,并测试其基础性能。分别使用3种纱线织制平纹、蜂巢2种不同组织的机织物,探讨不同材料、厚度及排列方式对于织物吸声效能的影响。结果表明:所纺不同线密度包芯纱的质量均良好稳定,不同材料中包芯玄武岩织物的平均吸声性能最好;玄武岩平纹织物叠加到厚度3 mm的吸声性能时良好,但随着厚度增加,中低频吸声系数稍有下降;将2种组织织物交替复合的方式形成不同梯度的多孔结构,可显著提高织物的吸声性能,低中频的平均吸声系数在0.2以上,高频吸声系数可达0.7。     

中空涤纶增强橡胶基复合材料层合非织造布的吸声性能

为改进氢化羧基丁腈橡胶（HXNBR）/单孔中空涤纶短纤复合材料（HF）在中低频的吸声性能,将厚度为1 mm、质量比为70/30制取的HF与厚度为3mm、面密度为300g/ m²的针刺单孔中空涤纶短纤非织造布（NPH）层合制取了双层材料 HF-NPH、三层材料 HF-NPH-HF 和 NPH-HF-NPH。研究认为：双层材料以HF为入射面可有效改进材料在中低频的吸声性能,吸声系数在 750Hz 处达到峰值 0.761,吸声系数大于 0.2 的有效频域为550~1700Hz,但在 1700Hz 以上中高频吸声性能 差;三层材料则在中低频吸声性能优异的同时中高频吸声性能也较好,吸声系数大于 0.2 的有效频域均为 450~2500Hz,在此范围内平均吸声系数均大于0.56,但总体上NPH-HF-NPH吸声性能更优。     

废弃纤维吸声复合材料的制备及其吸声性能

针对废弃纺织纤维利用率不高的问题,采用共混-热压工艺,以废弃纤维为增强材料,以热塑性聚氨酯为基体材料,制备废弃纤维/聚氨酯复合材料。将废弃纤维/聚氨酯复合材料加工成穿孔板,并与废弃涤纶织物贴合,构成吸声复合材料。重点研究吸声复合材料中穿孔直径、穿孔板厚度、穿孔率及废弃涤纶织物层数四种结构参数对材料吸声性能的影响。结果表明,穿孔直径主要影响吸声材料的吸声系数峰值;穿孔板厚度、穿孔率和废弃涤纶织物的层数主要影响吸声材料的吸声频带范围。     

废弃羽毛的结构特征及其吸声性能

为对废弃羽毛资源进行合理化利用,借助多功能纤维投影仪、扫描电子显微镜、傅里叶变换红外光谱仪和X射线衍射仪分析了羽毛的大分子结构、聚集态结构及其形态结构,探究了羽毛结构与其吸声性能之间的关系。采用声阻抗传递函数法对羽毛及其他几种可用于吸声领域的纤维集合体进行吸声性能测试及对比。结果表明:几种纤维集合体吸声性能排序为废弃羽毛、木棉纤维、羊毛、大麻纤维、涤纶;在整个测试频率范围内废弃羽毛的吸声性能随纤维集合体密度的增加而提高,且纤维集合体最大吸声系数对应的吸声频率随纤维集合体密度的增加逐渐降低;废弃羽毛纤维具有优良的吸声性能,在吸声领域具有很高的应用价值。     

废弃涤纶织物/氯化聚乙烯复合材料的隔声性能

为解决废旧纺织纤维资源化利用问题和日常生活中的噪声污染,采用废弃涤纶织物与氯化聚乙烯逐层贴合,热压制得具有良好隔声效果的隔声复合材料。通过对废弃涤纶织物、纯氯化聚乙烯（CPE）板、废弃涤纶织物/CPE层合隔声材料的隔声量曲线分析发现,废弃涤纶织物/CPE层合复合材料的隔声性能最好;改变废弃涤纶织物层数、面密度和加压压力,制得不同参数的废弃涤纶织物/CPE层合复合材料。通过对隔声量曲线分析可知,随废弃涤纶织物层数、材料面密度和加压压力的增加,其隔声量提高;对隔声复合材料的隔声量进行理论计算,并与实际测量值进行对比分析,结果表明理论计算值与实际测量值有较好的吻合性。     

基于BP神经网络的非织造材料基复合吸声体吸声系数预测

以涤纶针刺非织造材料和聚丙烯熔喷非织造材料为研究对象,通过实验获得其物理结构参数,并将复合前后非织造材料厚度、面密度、孔隙率和孔径作为BP神经网络的输入项,用于预测吸声体的平均吸声系数,同时通过调节输入神经元个数、传递函数和隐含层个数构建了最佳的BP神经网络预测模型。对非织造材料基复合吸声体的吸声性能进行预测,并与测试结果进行了对比。结果表明,运用BP神经网络可以建立较理想的适用于复合吸声体平均吸声系数预测的模型。     

Sound-Absorption Properties of Kapok Fiber Nonwoven Fabrics at Low Frequency

In this study, the sound-absorption properties of kapok fiber nonwoven fabrics were investigated in the frequency region of 100–2500 Hz using the impedance tube method. The effects of physical parameters including fiber mixing ratio, bulk density, and thickness on sound-absorption properties of composites were studied. The comparisons of kapok fiber with polypropylene fiber and hollow polyester fiber indicated that as a natural fiber, kapok fiber had superior acoustical properties at low frequency. A new simple model had been developed to predict the sound absorption coefficient of kapok fiber nonwoven composites at low frequency.     

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.     

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.     

废弃羊毛吸声复合材料的制备及其性能

为解决废弃羊毛再生循环利用问题,开发吸声系数高且吸声频带宽的吸声材料,以废弃羊毛为增强材料,乙烯醋酸乙烯共聚物（EVA）为基体材料,通过热压法制备了废弃羊毛/EVA 吸声复合材料。选用传递函数法分析废弃羊毛/EVA吸声复合材料的热压温度、材料密度、废弃羊毛质量分数、材料厚度、后空气层厚度以及废弃羊毛的排列方式等对吸声系数的影响。结果表明：用最优工艺制备的废弃羊毛/EVA吸声复合材料在低中高频都有优异吸声性能;该材料的吸声性能在中低频区域表现突出,在1 000 Hz处吸声系数达到0.9,材料降噪系数达0.65,平均吸声系数为0.6,即该材料为高效吸声材料;为吸声机制声波入射材料内部激发振动,声能转化为动能及热能,使废弃羊毛/EVA吸声复合材料具有优异吸声性能。     

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。     

针刺非织造材料形态与组合结构对材料吸声性能的影响

利用驻波管测试方法研究了几种不同厚度、不同密度和两种不同类型的纤维材料及其组合结构的吸声性能。研究结果表明,材料厚度的单因子条件与材料的吸声系数呈正线性相关;随着材料体积密度的增加,中低频声波的吸声系数提高,而高频声波的吸声系数呈现先提高后降低的趋势;材料的组合结构对材料的吸声性能影响很大,由中空纤维制成的低密度非织造材料与高密度非织造材料组合,并将高密度非织造材料置于表面,该组合方式的材料其吸声性能明显优于其他几种组合方式的材料。     

Manufacturing and properties of ultra-low density fiberboards with an unsaturated polyester resin by a dry process

Although ultra-low density fiberboards (ULDFs) have good sound and thermal insulation performance, formaldehyde emission in the manufacturing process and in the subsequent use of the products limits their field of application. The objective of this study was to employ an unsaturated polyester resin (UPR) in the manufacturing of the boards as a substitute of formaldehyde-based adhesives in order to develop environment-friendly ULDFs. The effects of UPR dosage, fiber treatment agent, press time and fiber consumption on the properties of fiberboards were studied. Sound absorption and thermal conductivity were also measured to ensure sound and thermal insulation properties of the fiberboards. Board density, modulus of rupture and thickness swelling in 2 h were 320 kg/m³, 4.14 MPa and 3.75%, respectively, under optimal conditions such as 12% UPR dosage, 1% fiber treatment agent, 400 g fiber consumption and 210 s press time. Noise reduction coefficient and thermal conductivity of the boards were found within a range of 0.68–0.58 and 0.038–0.048 W/(m K), respectively, while the density of boards ranged from 150 to 400 kg/m³. Therefore, sound absorption property of the fiberboards developed in this study satisfies the requirement of high-efficiency sound absorption materials, which is close to the value (0.67) of ULDF having a density of 56.3 kg/m³ obtained by a wet process. Thermal insulation property of boards was close to that of commonly used insulation materials such as rock wool [0.036 W/(m K)] and glass fiber [0.045 W/(m K)]. In conclusion, fiberboards can be used for non-structural furniture materials, sound and thermal insulation materials in buildings because of their environmental friendliness, good mechanical properties, and excellent sound and thermal insulation properties.     

Assessment of physical properties of fibres from thermoplastic polymers by means of tensiometric tests

Several properties of fibres and monofilaments made from polymers such as polyamide 6 (PA), poly(ethylene terephthalate) (PET), polypropylene (PP), aliphatic polyester of butanediol, succinic and adipic acids (PBSA), aliphatic-aromatic polyester of butanediol, terephthalic and adipic acids (PBTA) have been studied. Wettability of monofilaments has been tested by dynamic contact angle method, so surface free energy of synthetic fibres could be calculated. A tensiometer was used for testing the fibre-to-fibre friction coefficient, Young's modulus and bending modulus. It was found that the surface properties of fibres from synthetic polymers such as surface free energy, moisture absorption, and friction coefficient are related to the physical as well as physical–chemical properties, elasticity, elongation, thermal shrinkage and glass transition temperature. The good coherence of the tests performed with the theoretical relationship between Young's modulus of fibres and glass transition temperature of fibre-forming polymers clearly and definitely verifies the experimental results.     

Acoustic properties of sound-absorbing polyester fabrics woven with thick staple and thin draw textured yarn for use in interior decoration

Environmental pollution in our daily life because of noise is an increasing public health concern. We designed and woven with staple- and draw-textured yarns, for sound absorbance purposes. For wefts and warps, two different thicknesses of the thick staple-yarn and thin draw-textured filament yarn were used. The prepared fabrics were classified in porous, medium, and dense, on the basis of their densities and air permeabilities, and the sound absorption coefficients of the fabrics were found to be linearly related to the air permeability. The sound absorption coefficient determined by the impedance tube method was higher for porous fabrics compared with that for dense fabrics in the high frequency region. By the reverberant field method, the sound absorption coefficients for all fabrics were highest in the low frequency region. Porous fabrics exhibited a shorter reverberation time and a higher sound absorption coefficient than dense fabrics owing to their good sound absorption property.     

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.     

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.     

废弃秸秆/聚己内酯吸声复合材料的制备与性能

为提高废弃秸秆的利用率,拓宽其应用领域,以废弃秸秆为增强原料,聚己内酯为基体材料,通过热压法制备废弃秸秆/聚己内酯吸声复合材料.在热压温度为120℃,压力为10 MPa,热压时间为20 min的条件下,通过实验探究秸秆质量分数、复合材料密度、复合材料厚度、后置空气层厚度等参数对吸声复合材料吸声性能的影响.结果表明:当秸...