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The present work deals with analyzing the effect of silicon dioxide on mechanical and thermal stability of hybrid polymer composite. Compression molding is adopted to develop the hybrid composite with constant 0.5 wt.% of graphene and varying wt.% of silicon dioxide (2, 4 & 6 wt.%). Modified hummers method is used to synthesis graphene by chemical exfoliation of graphene from graphite flakes. Mechanical properties of developed composite is investigated using tensile, flexural, impact and interlaminar shear testing follow by fracture surface analysis of tested samples. Thermal stability is examined by thermogravimetric analysis and functional group confirmation is carried out using Fourier transform infrared spectroscopy (FTIR). Investigation over mechanical properties of fabricated composite reveals that addition of silicon dioxide up to 4 wt.% depicted higher flexural and tensile strength. Increment in silicon dioxide percentage improves the toughness of composite. FTIR results confirms the presence of asymmetric stretching vibrations due the after effect of hybrid fillers. Thermogravimetric analysis results depict that incorporation silicon dioxide increases the activation of energy of matrix from ~ 24.2 to 31.5 kJ/mol. [ABSTRACT FROM AUTHOR]

To simultaneously endow thermal conductivity, high glass transition temperature (Tg) and healing capability to glass fiber/epoxy (GFREP) composite, dynamic crosslinked epoxy resin bearing reversible β-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth (GFC@BNNSs). The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated BNNSs. Then, the GFC@BNNSs were impregnated with the mixture of lower concentration (3-glycidyloxypropyl) trimethoxysilane grafted BN micron sheets, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride, which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical performances. The resultant GFREP composite containing less boron nitride particles (17.6 wt%) exhibited superior in-plane (3.29 W·m−1·K−1) and through-plane (1.16 W·m−1·K−1) thermal conductivities, as well as high Tg of 204 °C (Tg of the unfilled epoxy=177 °C). The reversible transesterification reaction enabled closure of interlaminar cracks within the composite, achieving decent healing efficiencies estimated by means of tensile strength (71.2%), electrical breakdown strength (83.6%) and thermal conductivity (69.1%). The present work overcame the disadvantages of conventional thermally conductive composites, and provided an efficient approach to prolong the life span of thermally conductive GFREP laminate for high-temperature resistant integrated circuit application. [ABSTRACT FROM AUTHOR]

Silicon fillers have recently been employed as a multifunctional material to improve polymer composites' dielectric strength and mechanical strength, widely used to fabricate high-performance structural components. However, the mechanical strength was altered by adding silicon filler particles, leading to machining challenges that caused issues with quality and surface characteristics due to brittle fracture of silicon particles and related damage. The silicon filler 0, 3, 5, and 10% filled polymer matrix glass fibre reinforced composite was fabricated, and then abrasive water jet machining was used to investigate the machinability of the fabricated composite by considering silicon concentration, water jet pressure (WP), standoff distance (ND), traverse speed (ST). The machinability of the composite was established for quality-affecting responses such as kerf taper angle (KTA) and surface roughness (Ra). Silicon-filled polymer composites exhibit a higher dielectric constant than epoxy-glass fibre composites. An increase in silicon filler fraction decreases the surface roughness (Ra) and kerf taper angle (KTA), specifically at 5% of silicon filler, resulting in better machining quality. In contrast, 10% silicon filler increases those two responses to a high level, resulting in lower usage in considered applications due to more direct interaction between silicon filler and garnet abrasive grains. Increasing water jet pressure (WP) and decreasing standoff distance (ND) and traverse speed (ST) improve the machinability of silicon-filled composites. An SEM study of the surface topography reveals smooth cutting and finishing at high water jet pressure (WP) and 5% silicon particles. [ABSTRACT FROM AUTHOR]

Nanodiamonds (NDs) are the potential fillers to provide excellent mechanical and multi-functional capabilities. The growing interest in using NDs in a variety of fields has prompted researchers to use NDs to prepare various structural composites. Proper dispersion and interfacial adhesion between the NDs and the polymer matrix are required to use NDs as effective reinforcement in polymer nanocomposites. In this study, the mechanical properties of the epoxy-based glass fiber (GF)- and carbon fiber (CF)-reinforced laminated composites with the incorporation of annealed nanodiamonds (NDs) in the epoxy matrix was analyzed. The epoxy resin was modified through the step-wise addition of annealed NDs from 0.1 to 0.5 wt.%. The surface-modified NDs were characterized by SEM, XRD, FTIR, and TEM. The test results predict that the tensile strength was increased by 25, 23%, and tensile modulus increases by 33, 135% for GF- and CF-reinforced hybrid composites corresponding to the addition of 0.3 wt.% NDs into the epoxy matrix. Also, the flexural strength increased by 36, 37%, and flexural modulus increased by 71, 37% for the GF- and the CF-reinforced hybrid composites corresponding to the addition of 0.3 wt.% NDs into the epoxy matrix. These improved properties of hybrid composites are mainly due to the enhanced mechanical interlocking and weak Van der Waals force between the NDs particles that caused the efficient dispersion of NDs in the epoxy matrix and it has been reported in this study. [ABSTRACT FROM AUTHOR]

Recently, the utilization of hybrid basalt/glass fiber reinforced polymer (HBGFRP) nanocomposites has increased significantly in structural applications due to their light weight nature, superior strength-to-weight ratio, and excellent mechanical, chemical, and thermal properties. This study aims to investigate the effects of various drilling parameters and filler weight content on delamination and surface roughness on HBGFRP nanocomposites filled with combination of multi-walled carbon nanotubes (MWCNTs) and nano-silica particles (SiO2) in equal weight proportions of 0%, 1%, and 2%. These nanocomposite laminates were fabricated using the manual lay-up method followed by compression molding with a novel stacking order of fibers 01B/02G/02B/02G/02B/02G/01B consisting of 12 layers.. In this work, the Box-Benkhen Design of Response Surface Methodology (RSM) was employed to optimize the drilling parameters, including spindle speed, feed rate, drill diameter, and weight content of MWCNTs + SiO2. The nanocomposites containing 1.0wt. % MWCNTs + SiO2 demonstrated the most significant reduction in the delamination factor, achieving a 24% reduction. The lowest delamination factor recorded was 1.29, obtained with a spindle speed of 1350 rpm, a feed rate of 0.1 mm/rev, a drill diameter of 6 mm, and the addition of 1.0wt. % MWCNTs + SiO2. Increasing the spindle speed resulted in a further reduction in the delamination factor. The surface roughness measured was 1.213 µm, indicating a relatively smooth surface. It was evident that increase in feed rate and drill diameter corresponded to increase in both delamination factor and surface roughness. [ABSTRACT FROM AUTHOR]

Surface tuned GO sheets are considered the opportune pothunter for the reinforcement of conventional glass fiber reinforced composites (GFRCs). Herein, we have tried to disseminate the effects of N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane functionalized GO (GO-AEAPTS) and pristine GO sheets on thermo-mechanical properties of epoxy/glass fiber composites. Fourier Transform-infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering (DLS) and transmission electron microscope (TEM) were used to characterize the GO sheets. Multiscale composites integrated with GO-AEAPTS (1.5 wt%) provided maximum gain in all the studied properties i.e., interlaminar shear strength (ILSS), impact strength and thermal conductivity were improved by ~ 55, ~ 24 and ~ 70%, respectively. Storage modulus and glass transition temperature increased by ~ 44% and 14 °C, over the neat GFRC. In addition, GO-AEAPTS composites exhibited higher coefficient of effectiveness and crosslink density than those of GO counterparts. These property enhancements were credited to the homogeneous distribution of GO sheets, strong interfacial interactions (interfacial covalent interactions and hydrogen bonding) between GO-AEAPTS and epoxy resin as well as good fiber/matrix compatibility. Such multiscale composites with functional properties can outperform conventional counterparts with improved safety and reliability of structures and reduce maintenance costs. [ABSTRACT FROM AUTHOR]

Microfibrillated cellulose (MFC) has the potential to be used as an alternate reinforcement to glass fibers. However, glass fiber reinforced epoxy composites at usual operating temperatures (below Tg) are still superior to MFC infused epoxy composites. In this work, MFC mats with variable amounts of graphene oxide (GO) crosslinking were prepared using epichlorohydrin. Crosslinked MFC/GO epoxy composites with constant fiber content and different GO loadings were fabricated by impregnation of the freeze-dried crosslinked MFC/GO mats with the epoxy/hardener mixture followed by compression molding. Composites with 15 vol% MFC and 2 wt% GO crosslinking exhibit a storage modulus in the glassy state (40 °C) of 6.5 GPa, which surpasses the storage modulus of glass fiber/epoxy composite with similar fiber volume content (6.2 GPa at 40 °C). Thus, with a small amount of GO crosslinking, MFC was shown to possess superior modulus and lower weight when compared to glass fiber composites at similar fiber volume content. [ABSTRACT FROM AUTHOR]

The first part of the paper deals with homogenization models of unidirectional composites, in which each phase of the material is bounded by parallel cylindrical surfaces. For a GFRP with epoxy resin and glass fibres, five elastic constants for six models of the composite are calculated. In the second part, the results of strain gauge tests, photoelasticity investigations, and scanning electron inspection are discussed. With these data, some elastic constants of the composite in tension and compression are found. A comparison of experimental and analytical results is presented. [ABSTRACT FROM AUTHOR]