环氧树脂-玻璃微珠多孔复合材料的水声性能

为提高薄板吸声材料的吸声性能,用改性环氧树脂和空心玻璃微珠等原料合成了25mm厚环氧树脂-玻璃微珠多孔复合材料,在脉冲声管中测试了合成材料试样的声压反射系数和吸声系数,研究了合成工艺参数对其水下声学性能的影响.测试结果表明:环氧树脂-玻璃微珠多孔复合材料是一种良好的水下吸声材料,其吸声性能受到空心玻璃微珠的种类及其含量和固化剂种类等参数的影响.制备了填充多种空心玻璃微珠低频吸声性能良好的环氧树脂-玻璃微珠声学材料.合理地设计实验工艺参数,可以得到水下声学性能更佳的环氧树脂-玻璃微珠多孔复合材料.     

空心玻璃微珠复合聚酰亚胺泡沫的泡孔结构与性能

通过填充空心玻璃微珠,采用预聚法制备了空心玻璃微珠复合聚酰亚胺泡沫,研究了空心玻璃微珠填充量对复合聚酰亚胺泡沫的泡孔结构、热性能和压缩性能的影响规律。结果表明,随着空心玻璃微珠填充量的增加,聚酰亚胺泡沫泡孔结构变得精细,并且热稳定性、玻璃化转变温度和压缩性能都随之提高。当填充量(空心玻璃微珠与均苯四甲酸酐的质量比)达到20%时,泡沫5%热失重温度提高了13.9℃,玻璃化转变温度提高了8.1℃,压缩强度提高了约21%,压缩模量提高了约12%。     

新型光、 热双响应形状记忆聚合物的制备与性能

通过多巴胺表面原位聚合反应修饰玻璃微珠, 利用X光电子能谱仪(XPS)和傅里叶变换红外光谱仪 (FTIR)对修饰前后玻璃微珠表面的化学组成进行了表征, 用热失重分析仪(TGA)对其热稳定性进行了测试, 并利用透射电子显微镜(TEM)和扫描电子显微镜(SEM)对其形貌进行了观察; 研究了改性玻璃微珠对形状记忆共混物聚己内酯和聚氨酯(PCL/TPU)的热性能、 力学性能和形状记忆性能的影响. 结果表明, 成功制备了表面包覆聚多巴胺的玻璃微珠(PHGM), 改性玻璃微珠的加入不仅增强了复合材料的力学性能(当改性玻璃微珠含量为3%时, 材料的拉伸强度提高到53.3 MPa, 杨氏模量提高到178.4 MPa), 还赋予了复合材料优异的光热效应. 所制备的形状记忆复合材料在808 nm近红外光的照射下, 可以在短时间内(7 s)升高到材料的开关温度并回复到初始形状.     

环氧树脂增韧改性的研究进展

环氧树脂作为主要的热固性树脂之一,性能优异,应用广泛。但由于其固化交联密度高,脆性大的缺点,环氧树脂的实际应用受到了极大地限制。因此,环氧树脂的增韧改性成为了人们研究的重点。本文主要从橡胶、聚硅氧烷、热塑性塑料、树枝状聚合物、嵌段聚合物、纳米填料这几种主要增韧材料出发,系统综述了近几年来环氧树脂增韧改性的研究进展,简要阐述了各种材料的增韧机制,并对环氧树脂增韧改性的研究进行了分析与展望。     

硬质PVC复合改性界面研究进展

综述了增强增韧硬质PVC方面所做的研究工作及最新的研究进展,探究了增强、增韧PVC的方法以及机理,机理包括:多重银纹,剪切屈服,剪切屈服-银纹化,逾渗,空穴。目前的改性方法包括:改性无机粒子增强增韧PVC,如微米粒子、纳米粒子、"核-壳"结构粒子、其它无机粒子;聚合物和无机粒子/聚合物以及接枝改性增强增韧PVC。     

无机纳米粒子在环氧树脂增韧改性中的应用

无机纳米粒子能够给聚合物赋以卓越的综合性能,为此,纳米材料在聚合物改性中的应用已成为聚合物改性领域中的一个研究热点。本文就近年来在环氧树脂增韧改性中应用的无机纳米粒子的种类、环氧树脂／无机纳米复合材料的制备方法及其应用研究进展进行了综述。     

刚性有机填料同时增韧增强改性硬PVC韧性体的研究

刚性有机填料(简称ROF)是用作塑料改性剂的刚性有机聚合物,如PS、PMMA、SAN等。实验发现将少许ROF填充到硬聚氯乙烯韧性体中,能使基体的冲击强度和拉伸强度同时提高,获得既增韧又增强的双重效果。克服了传统的弹性体增韧改性损害基体强度的缺陷。     

PTFE/纳米SiO2复合材料的制备及其力学性能

聚合物／纳米级无机粒子复合材料是纳米材料中的一种具有重要价值的新型材料，可广泛应用于橡胶、塑料、纤维三大合成材料之中。采用纳米级无机粒子填充聚合物基复合材料，可以在材料的补强、增韧等改性中获得良好的效果。本文以纳米SiO2为填料，将其经过有机处理后，制备了FIFE／纳米SiO2复合材料，并研究了纳米SiO2的含量对PTFE复合材料性能的影响。     

反应型POSS杂化纳米材料合成及其对聚合物的改性研究进展

多面体低聚笼型倍半硅氧烷(POSS)是一类分子内有机-无机杂化材料。该材料因为同时含有笼型的Si—O—Si核及键合在Si顶点上可设计的有机基团,所以兼具无机材料高的强度和耐温性以及有机基团灵活的可设计性,可广泛用于聚合物的改性。反应型POSS是指POSS上的有机基团与其改性聚合物有较高的反应活性,可以共价键合于聚合物分子链上,提高POSS在聚合物基体中的分散性,增强其界面粘接作用,更大程度提高聚合物的性能。本文综述了近年来反应型POSS的合成,POSS在聚合物增韧补强、耐热阻燃性能、介电性能改性等领域的研究进展,总结了POSS改善无机纳米粒子在聚合物改性体系分散性能方面的研究进展,并指出了今后的发展方向。     

道路反光标志带用玻璃微珠的表面化学修饰

道路反光标志带用的反光材料--玻璃微珠的反光性是人们关注的研究课题.国内外对玻璃微珠表面曾采用"真空镀铝"[1]、"NDI-301(或302)偶联剂"[2]进行改性.前者虽可提高玻璃微珠的反光性,但操作繁琐和成本高,后者只能提高玻璃微珠对树脂层的亲合力和粘接强度,反光性未获改善;并且两者均不能赋予发光性.鉴此,以铝-钛偶联剂、BCP-1170荧光粉及辅剂等化学修饰玻璃微珠表面,镀上光亮的铝-钛反光膜、发光膜,既提高了玻璃微珠的反光性,同时赋予发光性.     

Effects of hyperbranched poly(ester‐silane) as a coupling agent on the mechanical behavior of glass bead filled epoxy resin

Hyperbranched poly(ester‐silane)s (HPE‐Si, including HPE‐Si4 and HPE‐Si8) were synthesized for glass bead filled epoxy resins. The grafting reaction and the degree of grafting of HPE‐Si onto the surface of glass beads were characterized by Fourier transform infrared photoacoustic spectroscopy (FT‐IR‐PAS) and thermogravimetric analysis (TGA) measurements. The degree of grafting was calculated to be in the range 1.0–4.2% for different HPE‐Si treatments. The tensile strength and modulus of glass bead filled epoxy resins were found to increase with increasing filler content. Moreover, HPE‐Si4 series have the highest tensile strength and modulus at the same glass bead size and volume fraction in the composites compared with HPE‐Si8 series. The fracture toughness (K_1c) of specimens with different glass bead sizes (4.8 and 2.0 μm) has the same trend that changes with the filler content and the modification of the surface of glass beads. The investigation of the toughening mechanism using Irwin's model through the yield stress measurements suggest that the toughening mechanism for small glass bead filled resins does not involve matrix plasticity, whereas the toughening mechanism involving matrix shear banding for large glass bead filled resins with higher filler content (up to 10 wt%) was proposed. The morphology of the filled resins studied by scanning electron microscopy (SEM) showed that the interface compatibility between the glass beads and epoxy matrix was greatly improved by the treatment with HPE‐Si. Copyright © 2005 John Wiley & Sons, Ltd.     

Specificity of the application of disperse and fibrous fillers in heterophase polymer materials

The mechanism of the reinforcing effect of fillers in polymer composition is studied and the relation between the properties and structure of materials is established. It is shown that, upon the addition of even a small amount of filler, properties of polymers change markedly due to intermolecular interactions. Variations in the composition of filled polymers and conditions of their preparation make it possibly to regulate properties of polymers within noticeably wide ranges. Specific features of polymer compositions filled with polymer fibers, the effect of fiber length, and the degree of orientation on the strength of composition are considered. For crosslinked epoxy urethane polymers, the effect of glass and polycaproamide (capron) fibers on the mechanical properties of polymer clutches in glassy and rubbery states is studied. The possibility to realize the shape memory effect for shrinkable filled polymer clutches is demonstrated.     

剪切对玻璃珠填充聚丙烯结晶行为的影响

应用Linkam CSS450剪切仪、广角X射线衍射仪(WAXD)和小角X射线散射仪(SAXS)等研究了剪切对玻璃珠填充聚丙烯结晶行为的影响, 结果表明, 与纯聚丙烯相比, 填加玻璃珠的聚丙烯体系中, 玻璃珠起到成核剂的作用, 不利于β晶的生成. 玻璃珠直径较小(4 μm)时, 剪切对聚丙烯β晶的生成影响较小; 当玻璃珠直径增加到35 μm时, 剪切速率为20 s-1左右最有利于β晶生成; 剪切速率和玻璃珠直径的增加, 有利于聚丙烯片晶的取向, 而且玻璃珠含量越高, 片晶的取向程度越大.     

Effects of filler size and heat treatment on the crystallization behavior of glass bead‐filled polypropylene

The effects of glass bead (GB) size and annealing temperature on the formation of β‐crystals of glass bead‐filled polypropylene (PP) are studied in this articles. Differential scanning calorimetry (DSC) measurements indicated that the amount of β‐form in PP crystals was a function of the glass bead content and size. For a fixed glass bead content, it was found that the smaller the diameter of the glass bead, the higher was the content of β‐crystals formed in the PP. On the other hand, wide‐angle X‐ray diffraction (WAXD) measurements revealed that the annealing temperature was also a major factor that affected the crystallization behavior of glass bead‐filled PP. It seemed that the blends with different glass bead contents had their own optimal annealing temperatures for β‐crystal formation. As an example, when the glass bead content was 48 wt %, the optimal annealing temperature for β‐crystal formation was about 108 °C, whereas it shifted to 100 °C for 14 wt % glass bead‐filled polypropylene. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 306–313, 2005     

Morphology and tensile properties of glass bead filled low density polyethylene composites: MATERIAL PROPERTIES

The mechanical properties of glass bead filled low density polyethylene (LDPE) composites in tension have been investigated by using an Instron material testing machine. It is found that with increase of the glass bead weight fraction (φ) the tensile modulus (E_c) and the tensile yield stress (σ_yc) increase as a form of nonlinear function but contrary to the elongation strain at break; the correlation between E_c and φ accords with the logarithmic mixing rule and the relationship between σ_y and the volume fraction (φ_f) can be described by means of a second order equation; the effects of the glass bead diameter on the mechanical properties are not large; when φ and the bead size are suitable, the enhanced toughness effect of the filled-systems is more significant; the tensile strength of the glass bead filled system pretreated with a coupling agent are somewhat greater than those of the untreated system. In addition, the morphology of the samples is studied to explain the relationship between the micro-structure and the mechanical properties of the composites.     

Cavitation and cavity-free deformation of filled crystalline polymer systems

Main mechanisms of tough response of polymers are described. In heterogeneous polymer systems due to mechanical misfit between heterogeneities and the matrix a high negative pressure (tri-axial stress) is generated. The excessive negative pressure is the main reason of material cavitation. Cavitation appears to be another mechanism of tough response of the material to loading. Cavitation is a massive phenomenon in crystalline polymers and in all filled polymers. Cavitation itself does not consume much energy but allows for further toughening by activating other mechanisms. Examples of polypropylene filled with chalk modified by liquid, rubber and mineral filled polypropylene and syndiotactic polypropylene filled with chalk are described. Modes of deformation with significant compressive component of stress prevents for cavitation. Materials deformed in a cavity-free manner show much higher strength. It is pointed out that high polymer crystal anisotropy is necessary for the formation of a network of easy crystallographic slip in the unusual toughening of highly filled polymers observed recently. An example of syndiotactic polypropylene filled with submicro-chalk particles is presented.     

Glass bead grafting with poly(carboxylic acid) polymers and maleic anhydride copolymers

Glass beads were etched with acids and bases to increase the surface porosity and the number of silanol groups that could be used for grafting materials to the surfaces. The pretreated glass beads were functionalized using 3‐aminopropyltriethoxysilane (APS) coupling agent and then further chemically modified by reacting the carboxyl groups of carboxylic acid polymers with the amino groups of the pregrafted APS. Several carboxylic acid polymers and poly(maleic anhydride) copolymers, such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), poly(styrene‐alt‐maleic anhydride) (PSMA), and poly(ethylene‐alt‐maleic anhydride) (PEMA) were grafted onto the bead surface. The chemical modifications were investigated and characterized by FT‐IR spectroscopy, particle size analysis, and tensiometry for contact angle and porosity changes. The amount of APS and the different polymer grafted on the surface was determined from thermal gravimetric analysis and elemental analysis data. Spectroscopic studies and elemental analysis data showed that carboxylic acid polymers and maleic anhydride copolymers were chemically attached to the glass bead surface. The improved surface properties of surface modified glass beads were determined by measuring water and hexane penetration rates and contact angle. Contact angles increased and porosity decreased as the molecular weights of the polymer increased. The contact angles increased with the hydrophobicity of the attached polymer. The surface morphology was examined by scanning electron microscopy (SEM) and showed an increase in roughness for etched glass beads. Copyright © 2007 John Wiley & Sons, Ltd.     

Mechanical behavior of SBR–glass bead composites

The mechanical properties of crosslinked SBR containing varying amounts of a glass bead filler have been studied. It is shown that the stress–strain response at a given test rate and temperature can be rationalized provided dewetting around the glass bead filler is taken into account. Direct measurements of the volume dilatation as a function of both strain and filler content have been obtained. This information in conjunction with the model proposed herein has been used to satisfactorily reproduce the stress–strain curves to strains up to about 200%. It is also shown that at the break point complete dewetting has occurred so that the rupture properties of the filled are the same as that of the unfilled gum. This was found to be true for all temperatures and rates studied.     

Temperature dependence of relative modulus in filled polymer systems

The temperature dependence of relative modulus observed in filled thermoset, thermoplastic, and polyelectrolyte salt matrices is explained on the basis of induced stresses produced by the differences in the thermal expansion coefficients of the constituent materials. The analysis is based on the assumption that the modulus of the matrix in a filled polymer is less than that of the unfilled polymer. The temperature dependence of relative modulus is expressed as a function of the difference in thermal expansion coefficients, the volume fraction, the relative modulus in the unstressed state, and mechanical properties of the phases. Agreement is good between the analysis and experimental results for three systems: epoxy and glass, polyethylene and wollastonite, and a polyelectrolyte salt with mica and asbestos.     

核-壳粒子增韧聚合物的研究进展

核-壳粒子增韧结合了弹性体增韧和刚性粒子增强的优点，将其用于聚合物共混体系中有可能得到比基体树脂更高韧性更好刚性的复合材料。本文综述了相关核-壳粒子的分类、形态、形成机制，以及它们对聚合物基体的增韧机理，并详细阐述了反应性和非反应性聚合物共混体系中原位形成的核-壳粒子形态演化规律及其对共混物力学性能的影响。