Analysis of Particle Variation Effect on Flexural Properties of Hollow Glass Microsphere Filled Epoxy Matrix Syntactic Foam Composites

Abstract

Syntactic foam made from hollow glass microspheres (HGM) in an epoxy matrix has proven to be a good material with a strong structural strength. Understanding filler particle size variation is important in composite material formation, especially in syntactic foam, because of its numerous applications such as aerospace, marine, and structural purposes. In this present work, the effects of particle variation in different sizes (20–24 µm, 25–44 µm, 45–49 µm, and 50–60 µm) on the mechanical properties of the syntactic foam composites with a focus on flexural strength, modulus, and fracture surfaces are investigated. The particle sizes are varied into five volume fractions (5, 10, 15, 20, and 25 vol%). The results show that the highest flexural strength is 89 MPa at a 5 vol% fraction of 50–60 µm particle size variation with a 69% increase over the neat epoxy. This implies that the incorporation of HGM filler volume fraction and size variation has a strong effect on the flexural strength and bending modulus of syntactic foam. The highest particle size distribution is 31.02 at 25–44 µm. The storage modulus E’ increased at 30 °C, 50 °C, and 60 °C by 3.2%, 47%, and 96%, respectively. The effects of wall thickness and aspect ratio on the size of the microstructure, the fracture surfaces, and the viscoelastic properties are determined and reported accordingly.

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

“…The fractionation of the sizes was an experiment conducted to understand how a reduction in the density of the SFC can influence the improvement in specific tensile strength of the composite. This result is supported by the flexural properties of the SFC reported in our previous work [ 20 ]. This claim is also supported by the wall thickness “t” and the aspect ratio “a” of 5.990 µm and 9.188%, respectively, as reported in Table 2 .…”

“…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 ]. where d (as earlier reported by the authors [ 20 ]), , and are the average diameters of the particle distribution of T60-HGM, the average true density of particle distribution of T60-HGM, and the density of the wall material (2.56 g/cm 3 ), respectively.…”

“…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 ]. Furthermore, particle variation analysis was conducted using a gas pycnometer (Ultrapyc 5000 with 19 psi pressure by Anton Paar, Graz, Austria) to determine the densities of the varied sizes.…”

“…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 fracture surface of the e–SFCs were examined by scanning electron microscopy (SEM), using a Zeiss EVO 1 HD 15 Oxford instrument X-max. The tensile fracture specimens were used for SEM analysis, and they were gold-coated prior to the analysis using a Quorum Q 150R ES machine [ 20 ].…”