聚氨酯基水声吸声材料的合成工艺及改性

聚氨酯水声吸声材料是一种新型水声材料.分析聚氨酯吸声材料的微观阻尼吸声机理,从该机理出发,研究探讨聚氨酯水声吸声材料的合成工艺和改性方法.根据研究结果合成部分聚氨酯水声材料声学试样,在脉冲声管中测试试样的吸声系数,测试结果表明:聚氨酯材料是一种较好的水声吸声材料.通过合理控制实验工艺参数和改性方法,可以得到水声吸声性能更佳的聚氨酯水声材料.     

水声吸声材料研究进展

水声吸声材料常用于水下航行体表面,其研究对于水下目标的声隐身设计具有重要意义,在军事应用领域受到广泛关注。橡胶类和聚氨酯类粘弹性高分子材料因其独特的分子结构和可设计性得到广泛应用,此外吸声材料的结构设计对其性能也有着很大影响。本文在水声吸声材料吸声机理的基础上,对其主要材料体系和吸声结构进行了综述。     

PU/EP型水声吸声材料动态模量和声学参数的实验研究

采用聚氨酯(PU)和环氧树脂(EP)及云母填料合成了PU/EP二元IPN水声吸声材料,对该材料的动态模量和声速进行了测量,研究了EP含量和云母填料及含量对材料动态模量及声速的影响,并对材料的吸声性能进行了分析。结果表明,材料弹性模量越大,材料中声波传播速度就越大;随着填料含量的增加,声速的下降幅度增大。并用直观的物理量表征了抽象的声学量,为指导水声材料的设计提供了基础。     

聚氨酯水声吸声材料的体系探讨及其吸声结构的研究进展

分析了聚氨酯吸声材料的阻尼吸声机理,探讨了聚氨酯水声吸声材料的体系,从水下吸声结构的主要形式出发,对聚氨酯材料进行了类似的结构设计并对其研究进展进行了综述,最后对聚氨酯水下吸声结构发展趋势进行了展望。     

橡胶硫化三要素对水声橡胶吸声圆锥吸声性能的影响

用Φ120脉冲水声声管测量水声吸声材料的吸声系数，分析同一配方，在不同硫化工艺条件下，对水声橡胶吸声圆锥的吸声系数的影响。     

聚氨酯泡沫体吸声材料的双层复合效应研究

采用二次发泡工艺制备了聚氨酯双层复合泡沫吸声材料,对其吸声性能进行了理论预测与实验验证,并探讨了复合方式对泡沫材料吸声性能的影响。结果表明,用传递矩阵法来计算聚氨酯双层复合泡沫板材的吸声系数与实验测量结果基本吻合;双层复合聚氨酯板材较单层聚氨酯泡沫的吸声性能有所提高。     

复合材料孔隙含量超声多参量评价方法研究

复合材料由于其强度高、疲劳强度好等优点,在航空航天领域应用十分广泛。然而在其制备过程中易产生孔隙微缺陷,显著地降低了材料的最终力学性能。提出一种复合材料孔隙含量超声多参量评价方法,通过对超声相对非线性系数的测量,并对比研究声速、声衰减测量方法,建立复合材料孔隙微缺陷与各参量的定量联系和评价方法。实验结果表明,可采用超声相对非线性系数、声速和声衰减系数评价复合材料孔隙含量,其中声速能快速地反映复合材料的致密性,声衰减系数在一定尺寸范围内评价更加精准,对于声速和声衰减系数变化不明显的试块,采用超声相对非线性系数评价,为复合材料孔隙含量评价的研究提供了参考。     

聚合物基水声材料的研究进展

综述国内外聚合物基水声材料的研究进展。阐述聚合物基吸声材料的吸声机理,介绍填料类、泡沫类、结构类吸声聚合物的配方设计、结构设计和应用领域;从吸声机理、配方设计和应用方面,概述聚合物基透声材料、反声材料、去耦材料的研究现状。指出聚合物基水声材料的发展方向是宽频带、宽温域和耐深水压。     

改性PP基吸声体吸声性能的研究

本文以自行研制的乙现橡胶（ＥＰＲ）改性聚丙烯（ＰＰ）基阻燃泡沫材料制成吸声体,研究其吸声特性及规律。结果表明：该吸声体在中低频区域最大吸声系数可达到０．９９,在１２５～２０００ＨＺ频率内平均吸声系数为０．７２。     

高分子水声吸声材料的研究进展

概述了水声吸声材料的吸声机理,综述了常用的吸声结构以及相应结构的国内外水声吸声材料的研究现状.指出具有优良吸声性能且耐水压、低频、宽频段的高分子水声吸声材料是高分子水声吸声材料的发展趋势.     

无机填料对功能弹性体吸声性能的影响

基于调节聚氨酯/环氧树脂(PUR/EP)弹性体基材声阻抗,增加材料对声能弛豫吸收和传播路径、加大声波损耗的目的,在基材中加入空心玻璃微珠和云母两种无机材料,并通过改变无机材料的添加量和梯度结构设计对其水声吸声性能展开了研究。研究结果表明:无机填料云母和空心微珠的加入均能有效改善PUR/EP基材的吸声性能。空心微珠量越多,吸声效果越佳。云母添加量的影响规律为5%含量时平均吸声系数高,而高云母含量则只能对基材的低频吸声性能的提高贡献较大。这两种无机填料的梯度分层复合材料的吸声性能要优于非梯度材料(总含量10%)。     

Sound absorption characteristics of polymer microparticles

A sound absorption material composed of polymer microparticles and polyurethane (PU) foam with certain geometry cavum has been developed. Its sound‐absorbing characteristic was investigated in the impedance tube, according to transfer function method. Measurements show that polymer microparticles have remarkable effect on the absorption performance of the composite material because of their microstructures and features. Several models established for acoustic properties have been adopted to fit the experimental data. The results show that these models fail to predict accurately the acoustic properties of the materials. The sound energy attenuation in polymer microparticles material may most likely consist of two parts, viscous attenuation of air inside the pores and the friction energy caused by the oscillation of polymer particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2673–2679, 2006     

Mechanochemical devulcanization of ground tire rubber and its application in acoustic absorbent polyurethane foamed composites

The use of recycled rubber in preparation of acoustic absorbent materials will help to combat the existing environmental problems of both waste disposal and noise pollution. The focus of this work is to investigate the influence of mechanochemical pretreatment of ground tire rubber (GTR) on the acoustic absorption properties of polyurethane (PU)/GTR foamed composites. GTR subjected to pan‐milling could be mechanochemically devulcanized by breaking up the crosslinked structures through inducing fairly strong shearing and compressing forces. The significant increase in sol fraction of GTR confirmed the partial devulcanization during pan‐milling. Moreover, thermal gravimetric analysis indicated that rubber content in the soluble part of GTR was also remarkably increased. The devulcanization increased flexible chains of the GTR particles, which could help to improve damping properties as well as acoustic absorption ability of the PU/GTR foamed composites. Dynamic mechanical analysis and acoustic absorption measurements well confirmed this hypothesis. The loss modulus and sound absorption coefficient of PU/GTR foamed composites were remarkably increased through the mechanochemical pretreatment of GTR. The mechanochemical pretreatment also enhanced foamability of the composites as revealed by cell morphology. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Improvement of the acoustic and mechanical properties of sponge ethylene propylene diene rubber/carbon nanotube composites crosslinked by subsequent sulfur and electron beam irradiation

In this research, sponge ethylene propylene diene rubber (EPDM) nanocomposites based on functionalized multi-walled carbon nanotubes (f-MWCNTs) and foaming agent azodicarbonamide (AZD) were successfully fabricated as potential acoustic-absorbing foams. Two crosslinking systems were utilized for stabilizing the foam structure and improving its properties by subsequent sulfur and electron beam irradiation at 50 kGy as a fixed dose. The impacts of the concentration of AZD, f-MWCNTs and crosslinking systems on acoustic and physico-mechanical properties were investigated. The results manifested that the optimum foaming content was 3 phr. The acoustic data exhibited satisfactory enhancement in the sound absorption coefficient (α) for irradiated foam nanocomposites compared to unirradiated nanocomposites. This was attributed to the barrier effect of f-MWCNTs in reducing the pore size of the foam, leading to an increase in the tortuous path in the foam matrix that stifled the sound waves from transferring into the bulk. Likewise, the compression properties were also improved. However, tensile stress and strain at break values for irradiated foams relatively decreased. The data obtained revealed an excellent possibility of using these EPDM foam nanocomposites for potential applications such as acoustic panels and airborne sound insulation. © 2022 Society of Industrial Chemistry.     

结构设计及气泡型填料对水声吸声材料的影响综述

综述了水声吸声材料的结构设计现状以及气泡型填料改性水声吸声材料的研究概况,介绍了有望作为水声吸声材料的高分子树脂颗粒吸声材料的研究进展,指出了新型水下吸声材料的发展趋势。     

波形特征与层理岩石各向异性关系分析

岩石声学特性可以对岩石内部结构及力学特性进行描述与分类。通过对岩石声学特性的研究可以得到岩石爆破破碎所需的诸多信息。通过试验分析可知，声波速度与岩石爆破破碎效果密切相关，且岩石波形与岩石声波速度密切相关。声波波形与岩石破碎特征存在一定的相关性，波形在岩石不同方向上的差异性与岩石在不同方向上爆破破碎效果的差异性是相关的。     

Simultaneous Absorption of Hydrogen Sulfide and Carbon Dioxide into di-isopropanolamine Solution

The simultaneous absorption of hydrogen sulfide and carbon dioxide into di-isopropanolamine (DIPA) solution was investigated in a 183 cm long, 2.72 cm OD wetted-wall column at atmospheric pressure. The influence of liquid flow rate, gas flow rate, temperature and liquid concentration on the absorption rate, overall gas-phase mass transfer coefficient and selectivity factor were studied at a constant gas feed ratio. The results show that the absorption rate of CO₂ increases rapidly with increasing liquid flow rate (the Reynolds number of the turbulent liquid film ranges from 2600 to 4350) but increases moderately with increasing gas flow rate (G = 18-91 L/min), indicating that it is liquid-phase mass transfer controlled. In contrast, the absorption rate of H₂S increases very slowly with increasing liquid flow rate but increases rapidly with increasing gas flow rate, indicating that it is gas-phase mass transfer controlled. The absorption rate of CO₂ also increases with increasing temperature (26-80°C) but H₂S absorption rate decreases with increasing temperature. When the concentration of DIPA solution increases from 0.2 to 2.6 mol/L, the absorption rate of both CO₂ and H₂S increases but with a larger rate of increase for CO₂ For selective H₂S removal, it is preferable to operate at low liquid and high gas flow rates, low temperatures and low DIPA concentrations.     

声波团聚中尾流效应的理论研究

声波团聚是一项非常有潜力的颗粒物排放控制技术,最近的实验表明声波尾流效应是其中的重要机理。研究建立了Oseen条件下声波团聚中的尾流效应理论模型,并采用数值方法进行求解。研究了颗粒夹角、粒径和频率对声波尾流效应下的聚合速度的影响。计算结果表明,颗粒与声场的夹角对聚合速度影响很大,存在吸引和排斥两个区域。当夹角为0°~50°时,颗粒间存在强吸引作用,颗粒与声场平行时,聚合速度达到最大值;当夹角为50°～90°时,颗粒间表现为弱排斥作用,颗粒与声场垂直时,排斥速度最大。聚合速度随频率的增大而增加,但当频率超过某一临界值时,聚合速度基本保持不变;颗粒粒径越大,该临界频率越低。随着颗粒粒径的增大,聚合速度基本呈线性增加。     

Absorption of carbon dioxide into laminar falling films of aqueous kaolin slurries containing sodium hydroxide

To confirm the theory for gas absorption accompanied by an instantaneous irreversible reaction in laminar falling films of power-law liquids which was presented in a previous paper, experiments were carried out on the absorption of pure carbon dioxide into aqueous kaolin slurries containing sodium hydroxide by using a long wetted-wall column. The experimental data were in fairly good agreement with the theoretical predictions, the average deviation being 3.0%. The discussion on the effect of the power-law index of the liquid upon the reaction factor suggested an approximate method of estimating the reaction factors for power-law liquids.