Search

The design and development of thermal insulation materials is very important for the treatment of offshore oil pipelines. Understanding thermal energy transport in thermal insulation materials and predicting their thermal conductivities have important theoretical and practical value for the design of thermal insulation materials. In this work, lightweight and thermally insulated (LWTI) composites with the desired mechanical strength for offshore oil pipelines applications were prepared using epoxy resin (EP) as the matrix and hollow glass microspheres (HGMs) as the filler. The morphology, density, and mechanical properties of HGM/EP LWTI composites were studied first. The flexural strength and the flexural modulus of HGM/EP LWTI composites could still be as high as 22.34 &plusmn, 2.75 Mpa and 1.34 &plusmn, 0.03 GPa, respectively, while the density was only 0.591 g/cm3. The relationship between the effective thermal conductivity of HGM/EP LWTI composites and material parameters (sizes and contents together) has been studied systematically. A three-phase prediction model was built using the self-consistent approximation method to predict the effective thermal conductivity of HGM/EP LWTI composites, and the resin matrix, the wall thickness, the HGM particle size, and other parameters (such as air) were fully considered during the derivation of this three-phase thermal conductivity model. Finally, the insulation mechanism of HGM/EP LWTI composites was systematically analyzed. The thermal conductivities of HGM/EP LWTI composites with different diameters and HGM contents calculated by the three-phase prediction model agreed well with the experimental test results, with a minimum error of only 0.69%. Thus, this three-phase thermal conductivity model can be used to theoretically simulate the thermal conductivity of epoxy resin-based LWTI composites and can be the theoretical basis for the design and prediction of the thermal conductivity of other similar hollow spheres filled materials.

Purpose The purpose of this paper is to investigate the preparation and the flexural property of hollow glass microspheres (HGMs) filled resin-matrix composites, which have been widely applied in deep-sea fields. Design/methodology/approach The composites with different contents of HGMs from 47 to 57 Wt.% were studied. The voids in syntactic foams and their flexural properties were investigated. Findings The results showed that the voids quantity increased because of the increment of HGM content, whereas the exural strength and the exural modulus decreased. The fracture mechanism of the composites was also investigated by scanning electron microscope, which indicated that the composites failed by the crack extending through the microspheres. Research limitations/implications The advantages of HGMs with similar hollow spheres will be further investigated in a future research. Practical implications Results demonstrated that the properties of the composite might be tailored for specific application conditions by changing the HGM volume fraction. Originality/value The HGM filled resin-matrix composite materials have their unique properties and significant application potential. In this work, the resin-HGM composites were synthesized by mechanically mixing defined quantities of HGMs into epoxy resin, by which a kind of syntactic foams with good flexural properties could be obtained.

The density, thermal conductivity, and compressive properties of hollow glass microsphere (HGM)-filled epoxy composites were investigated in the present paper. The volume fraction of HGM was varied from 0 to 50 vol.%. The results showed density, thermal conductivity, compressive modulus, and compressive strength of the composites decreased with the increase of HGM volume fraction, which indicated that the properties related above were mainly dependent on the content of HGM. To conveniently predict thermal conductivity in the investigated materials system, five effective thermal conductivity models were analyzed and compared with the experimental data. The Agari model was applied to predict thermal conductivity of HGM-filled epoxy composites, and the results indicated thermal conductivity and compressive properties of epoxy–matrix composites can be modified by changing the HGM volume fraction, this discover would make it become a promising engineering material in the related fields.

The sensor localization is an essential function for the wireless sensor networks applications. Based on the characteristics of the DV-hop algorithm, an improved algorithm is proposed for this range-free localization algorithm. The main principle of the proposed algorithm is giving more consideration on network topology properties and making improved hop size estimation through proper tradeoff between network's global and local features. The results of the simulation experiment show its superiority in localization accuracy.