Loading Effect of Hollow Glass Microsphere (HGM) and Foam Microstructure on the Specific Mechanical Properties and Water Absorption of Syntactic Foam Composite

Abstract

Epoxy syntactic foams (SF) filled with hollow glass microspheres (HGM) were prepared by simple resin casting method and characterization in this study. The effect of varying the amount of HGM on the specific mechanical and water absorption properties of SF composites were investigated. Five different composition of SF (SFT60-0.5 to SFT60-2.5) were compared with the neat epoxy matrix. The wall thickness of the microballoons differ because of its different percentile size distribution (10th, 50th and 90th), which reflects in its density variation. The results show that the specific tensile and flexural strength increases with an increasing filler (HGM) content. The density of SF filled with HGM reduces with increasing volume fraction of filler content. Scanning electron microscopy was done on the failed samples to examine the fractured surfaces. The water absorption capacity of the SF was also investigated as it relates to the HGM volume fraction variation. All the syntactic foam composition shows a better diffusion coefficient capacity than the neat epoxy resin. This makes it applicable in structural purposes and several marine application products such as Autonomous Ultimately Vehicle (AUV).

Processing of Low-Density HGM-Filled Epoxy–Syntactic Foam Composites with High Specific Properties for Marine Applications

“…The HGM had a density of 0.6 g/cm 3 with particle sizes of 10–60 µm. The physiochemical characteristics and viscosity of the constituent components were discussed in our previous work [ 9 ]. The HGM was varied into four particle sizes using different sieve ranges and characterized by the particle distribution analysis (PSA) detailed process was reported earlier by the author [ 20 ].…”

“…Using a high-speed stirrer for 10 min, homogeneous dispersion of the HGM into LR20 was optimized. The viscosity changes experienced by the addition of HGM is presented in our previous work [ 9 ]. Later, LR281 was added to a homogeneous suspension of LR20-HGM and mixed for 5 min.…”

“…The 5 vol% was considered the lowest volume fraction because we are focusing on the lowest true density. Additionally, it was previously reported that good adhesion occurs in composite materials at a lower volume fraction [ 9 , 20 ]. The average wall thickness “t” is a measure of strength distribution and the aspect ratio “a”, which influences the strength of HGM particles, and was calculated using Equations (2) and (3), respectively [ 22 ].…”

“…The test was carried out on MTS 793 servo-hydraulic machine with a load cell of 30 KN. Detailed test parameters were discussed earlier by the author [ 9 ].…”

“…SFCs have been studied to exhibit the same density before and after curing, making them suitable in aerospace applications [ 6 , 7 ]. SFCs exhibit differences in density because of the difference in the internal radius and not the outer radius; this was studied by Woldesenbet et al and Afolabi et al [ 8 , 9 ], which resulted in a considerable increase in the peak strength of a SFC for higher strain rates and increased density. This paper aims to improve our understanding of the effects of concentration and particle size on density.…”