Hollow Glass Microsphere Composites Research Articles

Water absorption in hollow glass microsphere composites under hydrostatic pressure: Mechanisms and influencing parameters

AbstractHollow glass microsphere composites, or syntactic foams, are widely used in marine environments due to their buoyancy. However, in service, loss of buoyancy occurs along time. This behavior is attributed to water absorption that leads to a mass increase of the material. This study investigates the water absorption of three types of syntactic foams under hydrostatic pressure with density ranging from 0.59 to 0.74 g. cm−3. Water absorption measurements are performed for a maximal duration of 3 years and under hydrostatic pressure up to 700 bars. Results show that water absorption is much higher than expected and attributed to the filling of microspheres that collapse over time. Based on results presented here, prediction of water absorption syntactic foams is proposed including the impact of applied hydrostatic pressure. This prediction allows estimating the buoyancy loss in hollow glass microsphere composite as a function of time, depth and sample size.

Novel triaxial experimental investigation on compressive behavior of hollow glass microspheres composites under varied temperature environments

In this paper, to fully explore the mechanical characteristic of hollow glass microspheres (HGM) composites in deep-sea environment, the compressive behavior of solid buoyancy materials under different temperature gradients and various stress states were studied by a triaxial test system. Through the analysis of experimental results, the glass transition temperature and energy absorption of the material were revealed. Such a content, will further be useful to construct the yield criterion and specialize the sensitivity of each parameter.

Hydrostatic strength of hollow glass microspheres composites: Influencing factors and modelling

This study deals with the hydrostatic strength of hollow glass microspheres composites, commonly known as syntactic foams, using model materials made of 0.15 g/cm3 microspheres with 3 types of matrix, two epoxies and one paraffin. More than 100 model material samples are characterized for that work. The hydrostatic strength of these composite materials is determined in a pressure vessel, which can go up to 100 MPa. Two major parameters are studied: stiffness of the matrix and microsphere volume content within the composite material. The results clearly show that the hydrostatic strength of the syntactic foam can be improved by an increase in matrix stiffness or a reduction in microspheres content. Based on experimental data an empirical model with two parameters is proposed to describe the hydrostatic strength of syntactic foam. The relevance of the model is discussed.

Mechanical Properties of Hollow Glass Microspheres Filled Jute Woven Comingled Composites

Hollow glass microsphere (HGM) filled jute composites were fabricated using woven comingled fabric. Tensile, drop weight impact and Charpy impact tests were conducted to study the effects of HGM to the jute laminates. The tensile properties were enhanced with the addition of 1.5 % HGM (19 % tensile strength and 6 % modulus) while further addition of HGM up to 3 % decreased the tensile properties (16 % tensile strength and 19 % modulus). The impact strength was improved by 10 % with the incorporation of 1.5 % HGM and an increase of 19 % was observed in the 3 % HGM composites compared to the control composites.

Heat-insulating materials with high-temperature resistance through binding hollow glass microspheres with vinyl-functionalized polyborosiloxane

In this study, a kind of novel heat-insulating material composed by the vinyl-functionalized polyborosiloxane (BSiO) and hollow glass microspheres (HGM) was successfully prepared. Under solvent-free condition, the BSiO was synthesized by reacting triethoxyvinylsilane (VTEOS) and boric acid by one-pot method and characterized by GPC, FT-IR, NMR-29Si, NMR-11B and TGA analysis. The results indicated that the monomer feed ratio of the reactant made a great difference on the molecular structure and thermal stability of the BSiO and the BSiO-2 showed the best thermal stability when the feeding ratio of VTEOS and BA was 1.5. Moreover, the ceramic conversion analysis indicated that the BSiO-2 tended to form the inorganic SiBOC nanocomposite. Properties, such as the microstructure, density, linear shrinkage, compressive strength and thermal conductivity, burning behavior and flame retardancy of the BSiO-2/HGM composites after different heat treatment, were studied. The SEM results showed that the BSiO-2 could effectively wet the surface of HGM and the HGM was glued together firmly. With the increase in heat treatment temperature, the density and thermal conductivity of BSiO-2/HGM composites reached the minimum value at 600 °C, while the compressive strength reached the maximum value. The result of flame retardancy study showed that the composites possessed high LOI value (> 50%) and hardly any smoke could be observed during the burning process. This indicated that the BSiO-2/HGM composites possessed excellent flame-retardant property and fire safety. This paper will provide ideas for the design and preparation of heat-insulating materials with polyborosiloxane as heat-resistant binder.

Preparation and thermal performance of novel form-stable phase change materials based on polyethylene glycol (PEG)/hollow glass microsphere composites for thermal energy storage

In this article, the hollow glass microsphere (HGS)/polyethylene glycol (PEG) composites were prepared as form-stable phase change materials (FSPCMs) for thermal energy storage (TES) via direct impregnation method. In the prepared composites, the PEG functioned as phase change substance and the HGS acted as supporting materials, which will prevent the leakage of PEG in phase change process. The chemical structure, surface morphology, crystalline properties, phase change properties, thermal reliability and stability of obtained composites were extensively studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermal cycling test and thermogravimetric analysis. FTIR spectra showed that there was no chemical reaction between HGS and PEG. The SEM images exhibited that the special structure and large surface of HGS had the ability of preventing the leakage of the melting PEG. XRD and DSC curves demonstrated the good crystalline properties of prepared composites with latent heat reach up to 124.8 J/g. Meanwhile, the prepared composites had excellent thermal reliability and stability. The prepared composites can be used as FSPCMs and have great potential in TES.

Synthesis and properties of UV-cured porous polymeric composites: Thermal conductivity, mechanical and thermal properties

ABSTRACTPorous polymeric composites containing hollow microspheres such as hollow organic microsphere (HOM) and hollow glass microsphere (HGM), respectively, up to 50 vol% were prepared by a UV-radiation photo-curing process. The non-porous sample was also prepared as a reference material. The comparative study on measured and theoretical thermal conductivity (k) revealed that HOM composites were in a category of the internal porous material (EMT model < k < parallel model) with spherical pore structure. In case of HGM composites which were considered as three-phasic material composed of bulk HPU matrix, thermal conductivity of HGM composites could be perfectly predicted by Felske model. From dynamic mechanical measurement, tensile and compression properties, it appeared that mechanical characteristics of hollow microspheres played an important role in storage modulus, Tg, and mechanical properties of composites. Especially, the incorporation of HGMs leaded to the reinforcement with increasing volume percentage of HGM in composites.

Low swelling poly(ester) urethane composite containing modified hollow glass microspheres for seawater-resistant encapsulant

A novel poly(ester) urethane system filled with poly(ester) urethane grafted with hollow glass microspheres was fabricated via a melt mixing method for use as an underwater encapsulant. The poly(ester) urethane/ poly(ester) urethane grafted with hollow glass microsphere (HGM) composites (PU/PU-g-HGM composites) were prepared using various PU-g-HGM contents. Studies of these composites showed that the swelling ratio of PU/PUg-HGM composites in seawater and paraffin oil decreased with increasing HGM content of grafted poly(ester) urethane, while the tensile strength of PU/PU-g-HGM composites could be incrementally increased by rising PU-g-HGM content. This finding is due to the enhanced interfacial adhesion between poly(ester) urethane and poly(ester) urethane-grafted HGM due to good compatibility between these components. The tensile strength of the PU/PU-g-HGM composites in seawater (or paraffin oil) also exhibited higher levels than those of poly(ester) urethane and PU/ pristine HGMs composites in seawater (or paraffin oil) as the immersion time increased. Therefore, the PU/PU-g-HGM composites were expected to have potential applications as underwater encapsulants. Open image in new window

Preparation and characterisation of ZnO nanorod array-coated hollow glass microsphere composites

Uniform and oriented ZnO nanorod arrays on the surface of hollow glass microspheres (HGMs) were fabricated by using a seed growth process in aqueous solution of zinc nitrate and hexamethylenetetramine at low temperature. The structure and morphology of as-obtained ZnO nanorod array-coated hollow glass microsphere (HGM/ZnO) composites were analysed by using X-ray diffraction and scanning electron microscopy. The results showed that all the HGMs were coated with a well-aligned layer of ZnO nanorod arrays and the ZnO nanorods possessed relatively uniform hexagonal rod structures and stood perpendicular. Moreover, the ZnO nanorod arrays were affected by a variety of growth conditions such as the growth solution concentration and the solution temperature.

Interface engineering via compatibilization in HDPE composite reinforced with sodium borosilicate hollow glass microspheres

In the present study dealing with hollow-sphere filled polymers, sodium borosilicate hollow glass microspheres (HGM) with the crushing strength of 30,000 psi were used as filler in high density polyethylene (HDPE). HGM remained intact in HDPE matrix with no sign of crushing during the compounding and injection molding operation. Polyethylene- graft-maleic anhydride (PE- g-MAH) used as compatibilizer resulted in nano sized needle like structure in the HGM HDPE interfacial region that resulted in enhanced mechanical properties of HDPE HGM composites.

A study on composites of Nylon-6 with hollow glass microspheres

The preparation of nylon-6/hollow glass microspheres composites by the RIM procedure, leading to a new material with reduced density and increased stiffness, is described. The shear moduli of these composites show a linear dependency on the filler concentration. By means of a modified Kerner equation the shear moduli of the various glass spheres were calculated. A linear dependency between the shear modulus of a glass sphere and its wall thickness is demonstrated. A direct method for the determination of the shear moduli of those glass spheres having a density lower than the matrix material is presented.

Hollow glass microsphere composites: preparation and properties

Composites consisting of bonded hollow glass microspheres are promising for constructions in which materials are needed that combine a high Young's modulus with a low density. The elastic properties of ideally bonded hollow glass microsphere composites are predicted theoretically. Heat-treated castings of quartz glass microspheres approach the theoretical Young's modulus from below. The best result achieved was a Young's modulus of about 1 GPa with a strength of about 0.8 MPa at a density of about 180 kg m−3. This was obtained with a casting of quartz glass microspheres, bonded with mono-aluminium phosphate. Composites made by pressing of appropriate microsphere/ binder mixtures, followed by heating, had a density that was lower than for castings but had a Young's modulus far below the theoretical value.