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The effects of marble processing wastewater physicochemical treatment sludge (K1) on polypropylene (PP) waste pyrolysis were investigated by lab-scale batch pyrolysis system. PP-K1 proportions and pyrolysis temperature were studied as variables and both were found to have influences onto pyrolysis char, oil/tar, gas fractions distribution, as well as pyrolysis char characteristics (determined via SEM, EDX, FTIR, TGA and XRD analyses). The influence of K1 could be related to its high mineral composition (CaCO3, CaMg(CO3)2 and (Mg0.03Ca0.97)(CO3)) which also detected in the char products. K1 acts as catalyst and remained unchanged in thermochemical reactions below 700°C. The main thermal degradation of PP occurs around 400–470°C, although it starts at about 300–350°C, whereas, K1 resulted in more thermal degradation at 300°C pyrolysis. As K1 dose increased, pyrolysis chars became more thermally stable with the pyrolysis temperature. Diverse types of chars in terms of porosity, thermal strength and chemical structure were produced with PP + K1 as compared to the PP chars. For example, with 10%–20% K1 doses, the chars are in aromatic structure while chars become aliphatic when K1 dosage increased to 30% or above. The structural diversity made these chars new products that can be used as raw material for subsequent purposes. This study provided a basis for the chars' physical and chemical properties which are needed for further research to develop new generation evaluation areas for them. Therefore, a new symbiotic upcycling approach has been presented for PP wastes and marble processing wastewater treatment sludge. [ABSTRACT FROM AUTHOR]

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]

In this study, phenolic novolac‐type epoxy (EPN) resin was modified with 4 wt% thermoplastic polystyrene (PS) waste and was used as the polymer matrix for the first time. Two types of composites were prepared: (i) nanocomposites with 1–3 wt% nanoclay (NC) and (ii) hybrid composites. Pristine (NC) and tetramethylammonium chloride modified nanoclays (MNC) were used at a 2 wt% ratio in hybrid composites with 25–35 wt% red mud waste (RMW). The corrosion protection properties of the coatings were determined by immersion test in 5 wt% NaOH, HCl, and NaCl solutions. The water sorption of hybrid composites varied between 1%–3.6% and 1%–5.3%, while it was between 0.82% and 1.02% in EPN‐PS/NC nanocomposites. The weight gain percentage values of hybrid composites in corrosive media for the base and salt solutions were determined much lower (0.59%–0.75% and 0.46%–0.59%, respectively) than water sorption. Surface morphologies of hybrid composites were examined by scanning electron microscopy before and after corrosion tests. MNC‐30 wt% RMW hybrid composite was found more suitable due to high corrosion resistance in basic and salty environments, storage modulus, loss modulus, and glass transition temperature (Tg) values (90.6°C) as compared with NC‐30 wt% RMW hybrid composite. [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]

Highlights Ultrasonic methods are more sensitive to defects such as voids, pores, and discontinuities that can diminish the true elastic and acoustic properties of materials compared to destructive testing. Therefore, the elastic properties and some acoustic properties of the epoxy phenol novolac modified with polystyrene (EPN‐PS) matrix‐based nano‐ and hybrid composites were determined for the first time using ultrasonic method. Montmorillonite‐type nanoclay (NC) and industrial red mud waste (RMW) at a rate of 1–4 and 15–35 wt% respectively, were used as fillers in the composite preparation. According to the results, the highest elastic coefficient values (L = 8.14 GPa, G = 1.76 GPa, K = 5.79 GPa and E = 4.80 GPa) were obtained in the EPN‐PS/NC1 (with 1 wt% NC) nanocomposite sample compared to the elastic properties of pure EPN and EPN‐PS, while the highest elastic coefficient values (L = 8.97 GPa, G = 2.19 GPa, K = 6.06 GPa, and E = 5.86 GPa) among hybrid composites (HC) were obtained for the HC35 containing 2 wt. % NC and 35 wt% RMW. Due to both its high elastic and good acoustic properties, wall panels and floors produced using HC35 hybrid composite can be used for sound insulation in noisy environments. First evaluation of the acoustic characteristics of epoxy phenol novolac modified with polystyrene‐nanoclay/red mud waste (EPN‐PS‐NC/RMW) composites. NC4 with 4 wt% nanoclay showed the lowest elastic and acoustic properties. Nanoclay ratio above 1 wt% reduces elastic and acoustic properties. The increasing RMW ratio in hybrid composites increases elastic properties. High elastic and acoustic properties make HC35 ideal for sound insulation. [ABSTRACT FROM AUTHOR]

In this study, a novel flame retardant ammonium tetrafluoroborate (ATFB) was successfully synthesized using boric acid (H3BO3) and ammonium hydrogen difluoride (NH4HF2) as the reactants. In addition to ATFB, aluminum hydroxide (Al(OH)3) was used as a flame retardant and red mud (RM) waste was used as a filler to prepare epoxy composite materials with enhanced flammability properties. The appropriate ratio of RM:ATFB:Al(OH)3 both in terms of combustion and mechanical properties was found to be 15:10:5 wt%. The tensile strength of the composite in this ratio was obtained as 112 MPa, while the neat ER was 46 MPa. The burnout of the composite with the appropriate RM:ATFB:Al(OH)3 ratio decreased in the first 10 seconds, and extinguished in 32 seconds. Moreover, the burned area of this composite was the smallest among all the others. The experimental and estimated LOI values for this composite was found as 26 and 29, respectively. [ABSTRACT FROM AUTHOR]