空心玻璃微珠对固体浮力材料性能的影响

建立了固体浮力材料胶液粘度、密度、压缩强度和弹性模量的解析法计算模型,分析了空心玻璃微珠(HGB)对固体浮力材料胶液粘度、密度、压缩强度、弹性模量和吸水率的影响。结果表明,粒径较大的空心玻璃微珠胶液粘度相对略低;空心玻璃微珠的体积分数固定时,固体浮力材料密度随着微珠密度的升高而升高,压缩强度随微珠强度的升高而升高,弹性模量随微珠模量的升高而升高;同一静水压下,固体浮力材料的吸水率随微珠强度的升高而减小。     

空心玻璃微珠填充固体浮力材料的制备及性能研究

以双酚A环氧树脂E51为基质原料,甲基四氢苯酐为固化剂,K25空心玻璃微珠为轻质填充物,采用模压成形的方法制备了空心玻璃微珠填充固体浮力材料。研究了玻璃微珠的填充率对体系粘度、浮力材料的密度、抗压强度及耐静水压性能的影响。结果表明,低密度空心微珠的引入,有效降低了固体浮力材料的密度,并且随着玻璃微珠填充量的增大,材料的理论计算密度与实际密度的偏差逐渐变大;浮力材料的单轴压缩强度和耐静水压强度随着空心玻璃微珠填充量的增大而降低,当玻璃微珠填充量超过18%时,材料性能下降幅度增大。     

空心玻璃微珠填充固体浮力材料的制备及性能研究

以双酚A环氧树脂E51为基质原料,甲基四氢苯酐为固化剂,K25空心玻璃微珠为轻质填充物,采用模压成形的方法制备了空心玻璃微珠填充固体浮力材料。研究了玻璃微珠的填充率对体系粘度、浮力材料的密度、抗压强度及耐静水压件能的影响。结果表明,低密度空心微珠的引入,有效降低了固体浮力材料的密度,并且随着玻璃微珠填充量的增大,材料的理论计算密度与实际密度的偏差逐渐变大;浮力材料的单轴压缩强度和耐静水压强度随着空心玻璃微珠填充量的增大而降低,当玻璃微珠填充量超过18％时,材料性能下降幅度增大。     

空心玻璃微珠/硅橡胶基柔性浮力材料的制备与性能研究

以牌号为HGS8000X的空心玻璃微珠(HGM)为填料,以液体硅橡胶(SR)为基体,采用真空辅助浇铸法和模压法制备柔性浮力材料,并研究空心玻璃微珠体积分数对柔性浮力材料的密度、拉伸性能、硬度和吸水率的影响。结果表明,所制备的柔性浮力材料的密度为0.6~0.8 g/cm3,在40 MPa水静压下2 h吸水率最大不超过0.25%,是良好的深海用柔性浮力材料;随着空心玻璃微珠添加量的增加,柔性浮力材料的密度降低,吸水率增加,弹性降低,硬度提高。     

模压成型高微珠含量复合泡沫材料的制备及性能研究

以牌号为HGS8000X的空心玻璃微珠为填充材料,以环氧树脂为基体,采用真空辅助模压成型法制备了空心玻璃微珠体积添加量为65%—70%的复合泡沫材料。研究了空心玻璃微珠的体积分数对材料的密度、压缩强度、吸水率以及耐静水压性能的影响。结果表明,当空心玻璃微珠体积分数为67%—69%时,材料综合性能性能最佳,可以保持50 MPa、24 h的吸水率小于1%和压缩强度大于80 MPa的情况下使材料的密度由0.65 g/cm3降低到0.60 g/cm3。分析指出,高微珠含量的复合泡沫材料的性能更大程度上依赖于由于环氧树脂缺失而导致的材料的显微结构和空心玻璃微珠受力状态的改变。     

全海深浮力材料的研究与制备

选用缩水甘油醚型环氧树脂、芳香族多胺固化剂和空心玻璃微珠等原材料制备了低密度、高强度的全海深浮力材料,研究了低密度空心玻璃微珠K1的加入量对浮力材料的密度、单轴压缩强度、耐静水压强度和吸水率等性能的影响.结果表明,在空心玻璃微珠总体积分数为66.7％的全海深浮力材料中,加入适量空心玻璃微珠K1取代空心玻璃微珠HM42,...     

玻璃微珠/环氧树脂胶结型复合材料的刚架-弹簧-阻尼模型

针对玻璃微珠/环氧树脂构成的胶结型颗粒复合材料提出了刚架-弹簧-阻尼模型。考虑到环氧树脂基体的阻尼特性,通过动态热机械分析,得到常温低频下环氧树脂的损耗因子,并应用于刚架-弹簧-阻尼模型。采用有限单元分析方法进行数值仿真分析,得到了玻璃微珠/环氧树脂胶结型复合材料损耗因子随玻璃微珠粒径增大的变化规律。结果表明:随着玻璃微珠粒径的增大,颗粒复合材料的刚架-弹簧-阻尼模型单元计算的损耗因子会逐渐增大,且切向损耗因子要比轴向的大;对整体材料而言,刚架-弹簧-阻尼有限元模型计算的损耗因子也会逐渐增大,其中,按照平面正四边形网格模型计算得到的损耗因子要大于平面正六边形网格模型,即颗粒复合材料的孔隙率越大,材料的损耗因子越大。仿真分析结果与实际材料的阻尼变化规律相符,这种模型是可靠的。      

环氧树脂基复合泡沫材料的研究

以环氧树脂为基体,空心玻璃微珠为填充材料制备了具有高强度、低密度的复合泡沫材料。系统研究了固化剂用量,空心玻璃微珠的填充量、偶联剂的用量等对复合泡沫材料的力学性能的影响,并采用扫描电镜分析了复合泡沫材料的断口形貌。研究表明:随着空心玻璃微珠填充量的增大,复合泡沫材料的压缩强度和密度逐渐降低;偶联剂的加入能有效地改善环氧树脂与空心玻璃微珠之间的界面作用,从而提高力学性能。     

环氧树脂基固体浮力材料的制备及性能研究

实验采用低密度空心玻璃微珠(HGMS)填充脂环族环氧树脂E-4221制备固体浮力材料。讨论了环氧树脂E-4221体系的固化工艺制度和树脂体系配方对固化环氧树脂材料强度的影响,测得固化树脂产物压缩强度范围值100～150 MPa。分析了树脂配方以及玻璃微珠体积含量对最终固体浮力材料性能的影响,通过优化条件制备出抗压强度在40～70 MPa之间,密度范围在0.5～0.7 g/cm3,吸水率低于0.2%的固体浮力材料,最后对浮力材料的压缩断面做了简要分析。     

空心玻璃微珠含量对浮力材料吸水性能的影响

以环氧树脂为基体,空心玻璃微珠为填充物制备得到轻质高压浮力材料。采用排水法计算浮力材料的密度,变容深海耐压模拟试验装置测试了浮力材料在高压环境下的吸水率。结果表明:随着空心玻璃微珠含量的增加,浮力材料的密度下降,同一静水压下浮力材料吸水率先缓慢增加后急速升高;不同静水压条件下,材料的吸水率在40MPa以下基本不变,高于40MPa时,材料的吸水率急剧升高。     

空心玻璃微珠/环氧树脂固体浮力材料模压成型工艺及性能

借鉴陶瓷材料模压成型工艺提出了适用于环氧树脂基固体浮力材料制备的真空辅助模压成型自由固化方法，实现了固体浮力材料制备过程中成型与固化环节的分离，为高性能固体浮力材料的制备提供了新方法。以环氧树脂(E-4221)为基体，空心玻璃微珠(Hollow glass microsphere, HGMS)做填充材料，采用模压成型自由固化方法制备高HGMS体积分数的HGMS/E-4221固体浮力材料，研究了HGMS体积分数、成型压力对HGMS/E-4221固体浮力材料密度、抗压强度、吸水率等性能的影响。结果表明，真空辅助模压成型自由固化方法适用于HGMS体积分数为65%~67%的HGMS/E-4221固体浮力材料制备，所获得的HGMS/E-4221固体浮力材料密度为0.621~0.655 g/cm3，适用深度可达到8 000~10 000 m。      

树脂基深水浮力材料压缩性能研究

为探究空心微珠填充量对树脂基深水浮力材料压缩性能的影响以及材料压缩破坏机理,基于Mori-Tanaka及Turesanyi方法对空心微珠填充环氧树脂基深水浮力材料的有效弹性模量及压缩强度进行了理论预测.制备了空心微珠填充环氧树脂基深水浮力材料,对不同空心微珠填充比的材料体系进行了单轴压缩试验,并通过扫描电镜观察了材料断裂面微观形貌.结果表明:随着空心微珠填充量增加,材料体系耐压强度降低,模量上升,且实验结果与理论预测吻合情况较好;空心微珠破损是深水浮力材料破坏的根本因素.     

空心微珠/环氧树脂高强浮力材料的性能及断裂分析

以环氧树脂为基体, 经硅烷活化处理的空心玻璃微珠(HGM)为填充剂, 制备了高强浮力材料。采用XRD、 FRIR分析了HGM的结构和硅烷处理效果, 通过密度测试和单轴静态压缩试验研究了HGM的类型和含量对浮力材料性能的影响, 利用SEM和吸水率试验研究了浮力材料的断裂特性和吸水性。结果表明: HGM为无定形结构; 硅烷分子接枝在HGM表面, 使得HGM与环氧树脂完好结合且两者界面没有间隙沟槽; HGM的较大比压缩强度有利于提高浮力材料的性能; 高强浮力材料密度为0.645~0.850 g/cm3, 抗压强度为60~93 MPa, 比压缩强度为92~112 MPa·cm3·g-1; HGM含量较少时, 浮力材料断裂表面HGM破裂处的基体环氧树脂有拖尾特征, HGM含量增多时, HGM的破坏程度不断增大直至完全破坏; 浮力材料具有较好的抗吸水性。      

A functionally graded syntactic foam material for high energy absorption under compression

A functionally graded structure for hollow particle (microballoon) filled syntactic foams is fabricated that is capable of withstanding compression for 60–75% strain without any significant loss in strength. The new functionally graded structure is based on creating a gradient in microballoon wall thickness. This material has the same volume fraction of microballoons throughout the structure, eliminating the undesirable effects of the present functionally graded composites containing a gradient of particle volume fraction. Three compositions of such material are fabricated and tested in the present study. Results show that the compressive modulus, strength, and total energy absorption of the new syntactic foams can be controlled by using appropriate type and volume fraction of microballoons.     

Influence of manufacturing parameters on the tensile strengths of hollow and solid glass fibres

Composites reinforced with hollow glass fibres (HGF) have been shown to display improved performance in flexural and compressive loading over materials reinforced with solid fibres. A major drawback associated with hollow fibre composites is reduced reinforcement cross-section for a given fibre volume fraction. It is suggested that the use of optimised manufacturing parameters may allow fibre strengths to be increased, offsetting the inherent strength reduction predicted for hollow fibre composites compared to solid fibre composites. Tensile tests have been performed on batches of hollow and solid fibres with a variety of geometry's to investigate the effects of fibre hollow fraction and manufacturing parameters on fibre strength. Hollow and solid glass fibres drawn under a variety of conditions display tensile strengths which reflect their manufacturing history. A mechanism is proposed whereby differential strains may be locked into the fibre during manufacture. This mechanism may provide an explanation for the strength variations observed. Average tensile strengths for solid and hollow glass fibres appear to increase according to the degree of residual strain differential. The principal manufacturing parameters influencing residual strain differential are draw rate and temperature. Further investigation is suggested into methods for determining heat transport mechanisms within the fibre neck-down zone.     

Determination of Dynamic Modulus of Syntactic and Particulate Foams by a Non‐Destructive Approach

Abstract: Developments in aviation posed requirement of lightweight, high strength and highly damage‐tolerant materials. Sandwich‐structured composites fulfilling these requirements have become the first choice for many aerospace applications as well as structural components for ground transport and marine vessels. Sandwich composites are a special class of composite materials which are widely used because of their high specific strength and high bending stiffness. Syntactic foams, which are hollow particle‐filled core materials used in sandwich composites, have recently emerged as attractive material for applications requiring low weight, low moisture absorption and high insulation properties. Quasi‐static and dynamic properties of these syntactic foams are commonly determined though various destructive techniques such as quasi‐static compression and split Hopkinson pressure bar testing. However, there is a need for characterising these materials non‐destructively in the field. The present study focuses on the prediction of dynamic Young's modulus using ultrasonic testing in various types of hollow particle‐reinforced syntactic foam and solid particulate composites. Hollow particle‐filled syntactic foams and solid particulate composites are fabricated with three different volume fractions of 10%, 30% and 60%. Longitudinal and shear wave velocities are used for calculating the dynamic modulus. Effect of longitudinal attenuation behaviour along with longitudinal and shear wave velocities on the varying density and volume fraction of syntactic foams is also discussed.