软质聚氨酯泡沫无卤阻燃研究进展

结合飞机使用的软质聚氨酯泡沫,综述了近10年来国内外有关其无卤阻燃剂的研究进展,包括含磷阻燃剂、含氮阻燃剂、无机阻燃剂和复合阻燃剂,介绍了相应的阻燃效果和阻燃机理等.指出采用具有抑烟性能的复合阻燃剂阻燃软质聚氨酯泡沫是必然趋势.     

柔性聚氨酯泡沫动态性能的测试和系统参数的识别

文章描述了车内座椅用柔性聚氨酯泡沫动态性能的测试技术和主要系统参数的识别方法。测试实验装置中一刚性质量块被安放在3英寸的泡沫立方体上,该泡沫立方体为系统唯一的弹性材料。整个动态系统模型化为一单自由度系统。实验装置可由刚性质量块上的小的脉冲激励或由激振器在底座上激励。对于脉冲激励,由于其振幅较小,泡沫变形较小,可简化为一线性、粘弹性材料;对于激振器激励,振幅较大,引起的泡沫变形亦较大,此时泡沫可看成非线性的、粘弹性材料。对以上两种情况,分别测试其系统响应并根据实验数据计算识别出系统的主要参数。     

Measurement of the Poisson’s ratio of flexible polyurethane foam and its influence on a uniaxial compression model

Previous attempts to model the uniaxial compression response of flexible polyurethane foam using a hyperelastic model for rubber-like materials assumed a zero Poisson’s ratio in the model development. The consequences of relaxing this assumption are explored in this investigation. First, measurements are made of the material’s Poisson’s ratio at high compression levels. The measured values range between 0.5 at 5% compression and −0.05 at 66% compression. The experimental results are combined with those of other investigators and incorporated into a nonlinear viscoelastic model for modeling uniaxial compression behavior. It is found that relaxing the zero Poisson’s ratio assumption decreases the accuracy of the model predictions, indicating that an alternative model structure may be required.     

A temperature- and strain-rate-dependent isotropic elasto-viscoplastic model for glass-fiber-reinforced polyurethane foam

The primary aim of the present study is to provide a new constitutive model and its computational procedure for a glass-fiber-reinforced polyurethane foam (RPUF) subjected to various cryogenic temperatures and compressive loading rates. A Frank–Brockman-type isotropic elasto-viscoplastic model was introduced to describe the hardening and softening phenomena of RPUF under compressive loads. In addition, the increase of the yield strength and plateau according to the change of temperature and strain rates was demonstrated using the given constitutive model. The introduced numerical model was transformed as an implicit form and was implemented into a user-defined subroutine of commercial finite element analysis (FEA) code, i.e., ABAQUS UMAT. Based on the developed material library, the complex elasto-plastic behavior of RPUF under various cryogenic temperatures and strain rates was numerically estimated. The variation of material internal variables, such as hardening and softening control parameters, was quantitatively investigated, and the temperature- and strain-rate-dependent empirical formulae, namely, a polynomial multiple regression model, were proposed. Finally, the simulation results were compared with a series of compressive test results to validate the proposed method. On using the developed numerical method, it might be feasible to predict the unknown stress–strain behavior of RPUF under arbitrary severe environments.     

Quasi-static and dynamic mechanical responses of hybrid laminated composites based on high-density flexible polyurethane foam

Hybrid laminated composites were fabricated based on high-density flexible polyurethane foam and reinforced with inter/intra-ply hybrid laminates. Transient responses of hybrid composites under quasi-static and dynamic loadings with various thicknesses and expansion factors were comparatively investigated. Experimental results revealed that foam cell collapse and hybrid laminates rupture were dominant mechanisms of energy absorption. Interlaminar stress and composite tensile strength determined the compressive potential energy and double-peak behavior. Quasi-static bursting and puncture resistances exhibited totally different relationships to various constructions and expansion factors. Energy dissipation capacity is influenced more significantly by the constant rate of transverse (CRT) puncture than dynamic puncture process. CRT puncture resistance is superior to the corresponding dynamic puncture resistance for all constructions. The hybrid laminated composites contributes to eliminate more than 95% of the incident force in the drop weight impact test. Compared with non-laminated panel, the hybrid laminated composites exhibited higher resistance to static and dynamic loadings.     

多孔弹性软质聚氨酯泡沫(PEFPUF)塑料的声学性能研究

通过驻波管法对多孔弹性软质聚氨酯泡沫(PEFPUF)塑料的声学性能进行了测试,分析了材料结构、材料厚度、腔深以及湿度对吸声性能的影响.结果表明,PEFPUF塑料为纤细的软"筋络"构成的类似蜂窝多孔的三维网状结构;材料厚度对其声学性能的影响较大;加大腔深,相当于增加厚度,可以较大的提高低频吸声系数;湿度对于声学性能具有一定的影响.     

Fractional derivative viscoelastic model for frequency-dependent complex moduli of automotive elastomers

Finite element modeling has been used extensively nowadays for predicting structural vibration and noise radiation of automobile engines and subsystems. However, many elastomeric components on the engines or subsystems are often omitted in the FE models due to primarily the lack of material properties at higher frequencies. The present paper describes a form of fractional derivative viscoelastic model for characterizing frequency-dependent complex moduli of elastomers. The model is used to predict the high frequency complex moduli of some fluoroelastomers with varying durometers. Excellent correlations between testing and prediction are obtained.     

In-situ deformation of an open-cell flexible polyurethane foam characterised by 3D computed microtomography

The deformation behaviour of an open-cell flexible polyurethane foam was observed using X-ray microtomography on the ID19 beamline at the ESRF in Grenoble, France. Tomographs, consisting of 1024 voxels cubed, were collected with a voxel size of 6.6 m from a small region near the centre of the foam at a range of compressive strains between 0 and 80%. The results show that the initial stages of compression are taken up by small amounts of elastic bending in struts that are inclined to the compression direction. At 23% strain, entirely collapsed bands were observed in the structure. By 63% strain, there was evidence of struts impinging on each other, corresponding to the densification regime. The compression of an irregular foam (i.e. one with strut length and cell size distributions) appears to involve a sudden change in modulus, accompanied by localised increases in density. Observations of this nature would have been extremely difficult to interpret unambiguously without the ability to carry out sequential microtomographic imaging under realistic in situ loading conditions. The process of finite element analysis (FEA) was begun by constructing node-strut models from the experimental data by a mathematical skeletonisation process. These were used to derive node coordination, strut-length and cell-size distributions. However, direct comparison of the elastic properties with FEA was hampered by the absence of periodicity in the experimentally determined foam structures.     

漂珠聚氨酯复合泡沫力学特性及本构模型研究

以粉煤灰漂珠为主要组分的复合泡沫具有较高的比强度和比吸能,在轻质抗冲击结构设计和缓冲防护领域极具应用潜力.然而,漂珠尺寸和增强相等因素对材料力学性能和行为的影响机制尚不清楚,且当前研究尚未构建该类复合泡沫的力学模型,不利于开展结构设计中材料选型和数值仿真等工作.为此,该研究针对漂珠尺寸和蜂窝铝增强相对复合泡沫的力学性能...     

Study on the moisture absorption of pyridine containing polyurethane for moisture-responsive shape memory effects

Supramolecular polymers are attractive in recent years. In this article, a series of pyridine containing polyurethanes (PUPys) with various pyridine contents and various MDI-BDO contents were synthesized from 1,6-hexamethylene diisocyanate (HDI), 1,4-butanediol (BDO), N,N-bis(2-hydroxylethyl) isonicotinamine (BINA) and diphenylmethane diisocyanate (MDI). Thereafter, the moisture absorption of PUPys was mainly investigated systematically from the effect of temperature, relative humidity (RH), pyridine content, MDI-BDO content, the mechanism, and the kinetic of moisture absorption. Results show that the moisture absorption process of PUPys matches with Fick’s second law in the initial stage. The moisture absorption is dependent on the content of N,N-bis(2-hydroxylethyl) isonicotinamine (BINA), e.g., the moisture absorption decreases with the increase of MDI-BDO content as well as the decrease of BINA content. In addition, the moisture absorption increases with the increase of temperature and relative humidity (RH). Accordingly, the moisture absorption process of PUPy45 at RH = 65% and T = 25° can be expressed with the equation: lnM _t  = 8.88–2975(1/T) + 0.5lnt. On the basis of the moisture absorption, the shape recovery process of PUPys film under the moisture condition support that PUPys show excellent moisture-responsive shape memory effects.     

Fractional derivative Fourier plane filter for phase-change visualization

Fractional derivatives of two-dimensional images have been discussed theoretically in terms of Fourier optics and computer simulated. Filters that realize the half-order differentiation can be either complex or real. We prove, in terms of fractional calculus, that the semiderivative filter is useful for the visualization of phase changes in a phase object in such a way that the output-image intensity is directly proportional to the first derivative of the input object. We give computer-simulated results of one-dimensional semidifferentiating.     

双马来酰亚胺/环氧树脂改性聚氨酯泡沫塑料的研究

用双马来酰亚胺对环氧树脂进行改性 ,然后用改性环氧树脂对聚氨酯泡沫塑料进行改性。确定了改性聚氨酯泡沫塑料的最佳配方 ,研究了玻璃纤维和玻璃微珠的加入对改性泡沫塑料耐热性的影响。结果表明 ,改性泡沫塑料比未改性的热变形温度有了显著提高。     

新型金属卟啉交联聚氨酯泡沫的合成及应用

合成了带有活性基团 (-OH)的四 (4 -羟基苯基 )卟啉 (H2 THPP)及其金属卟啉 ,通过1HNMR、IR、UV/VIS对其结构进行了表征。利用正交实验得出的最佳物料配方合成了新型金属卟啉交联聚氨酯泡沫 ,该泡沫拟用作汽车尾气 (低温 )处理中的催化剂。对该催化剂的性能进行了初步研究     

添加相变材料微胶囊的聚氨酯泡沫制备及表征

在聚氨酯发泡体系中加入正十八烷微胶囊,制备含有相变材料微胶囊的聚氨酯泡沫.相变材料微胶囊能很好的埋置于聚氨酯基体中,泡沫的储热量随微胶囊含量的增大而增大,舍有20%(wt)相变材料微胶囊的泡沫储热量为24.7J/g,该泡沫可用作保温材料.     

聚氨酯泡沫表面化学镀镍的研究

采用化学镀方法对聚氨酯泡沫进行处理,在其表面均匀包覆一层镍镀层,达到表面金属化改性的目的.分别用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、红外光谱仪(IR)和热重分析仪(TG)对化学镀镍前后聚氨酯泡沫的形貌、结构及热分解行为进行了表征.结果表明:通过化学镀工艺制备的镍镀层由直径为1～2μm的颗粒组成,且呈一定的取向.化学镀镍后聚氨酯泡沫的X射线衍射强度和红外透过率都有所降低.化学镀镍前后聚氨酯泡沫的TG曲线都由两个失重阶段构成,由于化学镀后聚氨酯泡沫表面的镍镀层被氧化,因此在650～1000℃之间,其TG曲线还呈现一定的上升趋势.     

Bactericidal polyurethane foam mattresses: Microbiological characterization and effectiveness

The antimicrobial compounds 2.4.4.″-tricloro-2″ hydroxydiphenyl ether (triclosan), 5-chloro-2-methyl-4-isothiazolin-3-one (isothiazolone) and bis(2-pyridylthio)zinc 1,1′-dioxide (zinc pyrithione) were incorporated into polyurethane foam matrixes. Concentrations of 0.20 wt.%, 0.50 wt.% and 1.00 wt.% of each biocide compound were used, and the infection reduction capacity was evaluated for different types of bacteria. The microbiological tests with polyurethane foams were performed with agar diffusion tests using the pour plate technique and analyzing the colony formation units (CFU) as a function of time. In preliminary tests, the micro-organisms Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella choleraesuis and Staphylococcus aureus were used. Tests in vitro showed that polyurethane foam containing zinc pyrithione gave the best performance. Genotoxicity tests were conducted to evaluate if the use of zinc pyrithione in the polyurethane causes harm to human users. Microbiological tests were also performed on the surfaces of mattresses that were produced with polyurethane foam to verify their antimicrobial properties. The significant decrease in the number of micro-organisms within the foam showed the effectiveness of the zinc pyrithione as an antimicrobial, while the genotoxicity tests demonstrated the absence of collateral effects for the users.     

Rigid polyurethane foam: Refrigerator cabinet design and construction

Factors affecting the manufacture and properties of foam used in refrigerator construction are discussed. The process for foam insulation of domestic refrigerators is described and comparisons are drawn between the original and most modern production techniques, showing how development of rigid polyurethane foam technology has assisted changes in refrigeration cabinet construction.     

温度对聚氨酯泡沫材料力学性能影响的研究

研究了温度对聚氨酯泡沫材料力学性能(强度、模量、压缩蠕变)的影响,并研究了在弹性范围内不同压缩应力水平下的压缩蠕变试验,拟合出了聚氨酯泡沫压缩蠕变曲线.