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This study aims to increase the flame retardancy of epoxy‐based composites by using various flame retardants together with colemanite filler (CLM), which is a very mineral‐rich boron type. As a flame retardant, aluminum hydroxide (Al(OH)3) and boron‐containing compounds: borax (BRX) and natural minerals (tincal (TNC) and colemanite (CLM)), as well as barium metaborate (BaMB) synthesized by us were used. Scanning electron microscopy (SEM), x‐ray powder diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), contact angle (CA), and particle size analysis were used to characterize the composites and additives. All boron compounds increased the thermal stability of the composites. Except for the ER/CLM‐BaMB composite, other composites' surface contact angles were over 90°. In terms of both combustion and thermal properties, the best CLM‐BaMB‐Al(OH)3‐TNC ratio was determined as 15:5:15:15. The tensile strength, self‐extinguishing time, estimated and experimental Limited Oxygen Index (LOI) values for this composite were determined as 96 MPa, 65 s, 29.6%, and 25%, respectively. In addition, ANOVA was applied to determine the effect of hybrid filler type and different weight ratios on the mechanical properties of composites. [ABSTRACT FROM AUTHOR]

This research was carried out to figure out the effect of chemical treatments of hazelnut shell powders (HSPs) on the elastic properties, ultrasonic wave velocities, and damping properties of bio‐based epoxy resin (BER) biocomposites. Natural hazelnut shells (HSs) were chemically treated using sodium hydroxide (NaOH), and acetic anhydride (AA). Then, HSs that were chemically treated with NaOH and AA, and HSs that were not subjected to chemical treatment were ground to obtain HSPs. The treated HSPs (HSP‐NaOH and HSP‐AA), and untreated HSPs were contributed to the neat BER in varied compositions such as 10–50 wt% to obtain the BER/HSP, BER/HSP‐NaOH, and BER/HSP‐AA biocomposites. The effect of untreated, and treated HSP ratios on the density, ultrasonic wave velocities, Young's modulus, Bulk modulus, Shear modulus, Poisson ratio, microhardness, and damping characteristics (attenuation coefficient, loss tangent and quality factor) of the novel HSP‐based biocomposites, was investigated by the ultrasonic pulse‐echo overlap method (PEOM). A significant increase in the density, ultrasonic wave velocities, and elastic modulus values of the biocomposites was seen compared to the neat BER. Based on the obtained elastic modulus values, the most appropriate combination ratio between the neat BER, and HSP‐NaOH was determined as 50:50. [ABSTRACT FROM AUTHOR]

A new bio‐based epoxy resin (BER) is produced by the esterification reaction between sebacic acid (SAc) as bio‐based acid and epichlorohydrin (ECH). The epoxy resin (ER) is modified with the BER. The biocomposites are prepared using untreated coconut shell powder (CSP), modified coconut shell powder (MCSP), and MER. The CSP and MCSP particles are mixed with MER in varied compositions (10–50 wt%) for preparation of the MER/CSP and MER/MCSP biocomposites. The influences of CSP and MCSP bio‐fillers amounts on the physical properties (density, elastic constants, acoustic impedance, ultrasonic micro‐hardness, and attenuation coefficient) of biocomposites are investigated using the ultrasonic pulse‐echo overlap method (PEOM). It was seen that the densities, both ultrasonic longitudinal and shear waves' velocity values of obtained biocomposites were higher than those of the MER. All elastic moduli of the MER/MCSP biocomposites have higher values than of the neat MER and MER/CSP biocomposites. [ABSTRACT FROM AUTHOR]

In this study, chemically modified walnut shells (WS) were used as the filling material for synthesis of bio‐based epoxy composites and added to the matrix at varied mass ratios (10%–50%). The shells were initially treated with alkali and then modified with three different organic acids (citric acid [CA], oxalic acid [OA], and formic acid [FA]). The WS were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectroscopy (EDX) and thermo gravimetric analyzer. The SEM and X‐ray diffraction were employed to observe the morphology of the composites. The influences of acid type and WS percentages on the mechanical, thermal and water sorption properties were investigated. The maximum tensile strength (124.8 MPa) was obtained with CA‐treated shells (CA‐WS) and followed by OA‐treated shells (OA‐WS) (117 MPa) and FA‐treated shells (FA‐WS) (96.5 MPa). Acid modification had a positive effect on Young's modulus as that of epoxy resins increased by 5.45%–50.91%. The treatment did not significantly affect hardness. The optimum amount of modified shells in the composites was found to be 20 wt%. Water sorption values changed in the range of 2.78%–3.42% for composites with 20 wt% WS and observed to increase with the filler amount in the composite. However, this trend and the slight decrease in thermal properties are not critical obstacles for the use of modified WS in the manufacture of inexpensive epoxy‐ and bio‐based eco‐friendly products. [ABSTRACT FROM AUTHOR]

Fatty acid waste was recycled as raw material and utilized to synthesize epoxy (HP) or unsaturated ester group (OEE) containing polymers. The radicalic polymerization between the styrene and itaconic acid was carried out, too. Glycidyl ester of styrene-itaconic acid copolymer was obtained by esterification reaction with epichlorohydrin. The polymers were characterized by means of Fourier transform infrared spectroscopy and chemical analysis. The polymers were incorporated into diglycidyl ether of bisphenol A type commercial epoxy resin to prepare composites. The effects of polymer structure and amount on the physico-mechanical and thermal properties of epoxy were investigated. Surface hardness, tensile strength, percentage elongation and stress at maximum load of the composites were obtained higher than pure epoxy resin. The composites reinforced with bio-based polymers showed about 74.55-243% increase in elastic modulus over the pure epoxy matrix. Obtained Young's modulus values were higher for composites with styrene-based polymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Marble waste was obtained from marble processing plant wastewater with precipitation using different coagulants, such as sepiolite, zeolite, and pumice in dosages of 0.5-8 g/500 mL and mixed in 20 wt % with commercial epoxy resin. The effects of marble, coagulant type and dosage on the physicomechanical and thermal properties were investigated. The incorporation of marble processing waste particles increases the 10% decomposition temperature of pure epoxy by 5-50°C. Surface hardness, tensile strength, percentage elongation, and stress at maximum load of the composites were higher than those of pure resin, too. The composites reinforced with marble processing waste-pumice showed about 10% increase in elastic modulus, whereas the composite reinforced with marble processing waste-sepiolite or zeolite showed about 76.67-143.33% increase in elastic modulus over the pure epoxy matrix. Scanning electron microscopy (SEM) was used for characterization of surface and cross sections of the composites to verify the results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

The effect of the binding of various polyfunctional groups to polystyrene's (PS's) aromatic ring on the elastic properties of the PS were investigated by an ultrasonic method. Various sets of samples were prepared by chemical modification of pure PSs having different molecular weights with SA, maleic anhydride, and phthalic anhydride. The ultrasonic wave velocities of modified PSs were measured with the pulse-echo method at room temperature by a computer-controlled analyzer and a digital oscilloscope. The values of the acoustic impedance, Poisson's ratio, and elasticity constants of the samples were calculated by the measured values of the densities and sound velocities. The longitudinal and shear wave velocities and the values of all elastic constants increased with chemical modification of the pure PS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

In this study, thermal chemical vapor deposition (CVD) method was utilized to fabricate carbon nanotubes (CNTs) using an Fe/Al catalyst. Plasma enhanced CVD (PECVD) was applied to coat CNTs surfaces with a hydrophobic poly(hexafluorobutyl acrylate) (PHFBA) thin film. Then pure CNT and surface-modified CNT (f -CNT) were used as nanofillers at 0.5–3 wt% in bisphenol-A (DGEBA) and phenolic novolac types epoxy (EPN) resins to produce composite materials with superior properties. For characterization of both types of CNTs, FTIR, XRD, SEM, TEM and TGA analyses were performed. The morphologies of composites were examined via XRD and SEM. Thermal properties of composites were revealed by TGA. The influences of CNT surface functionalization and matrix type on the thermal, mechanical, electrical conductivity and surface wettability properties of composites were investigated. EPN based composites exhibited higher mechanical properties than that DGEBA based ones. At 1.5 wt% f -CNTs, the Young's modulus and tensile strength of the nanocomposites were found 6.9 ± 0.50 GPa and 141.0 ± 7.8 MPa, respectively using DGEBA matrix; 8.7 ± 0.59 GPa and 153.4 ± 7.9 MPa respectively, using EPN matrix. Composites electrical conductivity increased with increasing both type CNTs amount and reached a maximum value of 10−4 S/m and 10−6 S/m at 3 wt% of neat and f -CNTs contents. • We produced CNTs using the CVD method. • In addition, plasma-enhanced CVD was applied to coat CNT surfaces with PHFBA thin film. • Pure CNT and f -CNT were used as nanofillers in ER and PhNE resins to produce composite materials. • The f -CNT composites showed improved mechanical, wettability with a higher hydrophobic surface and thermal properties. [ABSTRACT FROM AUTHOR]