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In this study, almond shell waste (ASW) as filling material, pure (ER), and waste polystyrene modified bisphenol-A type epoxy resin (ER-PS) were used to obtain biobased composite materials. The modification of ASW was carried out with NaOH and linoleic acid (LnA). Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Particle size distribution analyses were used in the characterization of ASW. Composites were prepared at filling ratios of 10-20-30-40-50% by mass using the casting technique. The morphology of the composites was characterized by SEM. The effects of epoxy matrix type and BK filling ratio on composites' mechanical, thermal, and water sorption properties were investigated. Tensile strength and modulus of elasticity (e-modulus) values of ERPS/ASW composites were lower, and tensile elongation values were higher than ER/ASW composites. The highest tensile strength values of 95-129 MPa were obtained for LnA modified ASW composites. The order of the tensile strength of the prepared ER matrix composites according to the filler type is: linoleic acid-modified ASW (LnA-ASW)>NaOH treated ASW (NaOH-ASW) > unmodified ASW. The most suitable ASW ratio was found as 30% by mass. e-modulus values of all modified ASW composites were higher than the epoxy matrix. According to the hardness test results, there was no significant difference between the composites. The water sorption of the composites increased depending on the ASW ratio and had a weakening effect on the mechanical properties. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) waste has become a major challenge for the conservation of the environment due to difficult degradation. For this reason, it is important to develop new recycling strategies for reusing this waste. In this work, the electrospinning technique was used to synthesize composite nanofibers of polyvinylpyrrolidone (PVP), recycling PET (RPET) that was obtained from the chemical recycling of postconsumer PET with glycolysis and styrene (ST) as a crosslinking agent. The polymer solutions were analyzed by viscosity and frequency sweeping, while the composite nanofibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and nanoindentation to compare their properties. The PVP nanofibers presented an average diameter of 257 nm; the RPET/PVP and RPET/PVP/ST composite nanofibers had average diameters of 361 nm and 394 nm, respectively; and the modulus of elasticity and hardness of the RPET/PVP/ST composite nanofibers were 29 and 20 times larger, respectively, than those of the PVP nanofibers. With the synthesis of these composite nanofibers, a new approach to PET recycling is presented. [ABSTRACT FROM AUTHOR]

Low-molecular-weight 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) was used to modify bamboo strips catalyzed by maleic anhydride. In this study, response surface methodology (RSM) was applied to optimize the treatment conditions for DMDHEU modification of bamboo. Three selected parameters, DMDHEU concentration, curing temperature, and curing time, were further optimized using response surface methodology via the box behnken design (BBD). The equilibrium moisture content (EMC), water absorption (WA), anti-swelling efficiency (ASE), mechanical properties, and mold resistances to (Aspergillus niger V. Tiegh, Penicillium citrinum Thom, Trichoderma viride Pers. ex Fr., and Botryodiplodia theobromae Pat.) were evaluated as the dependent variables. The results show that the dimensional stability and mold resistance of bamboo were enhanced remarkably, and the modulus of rupture (MOR) of bamboo was decreased after DMDHEU modification, while the modulus of elasticity (MOE) changed slightly, and the parallel-to-grain compressive strength (CS) was increased. Furthermore, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) were used to investigate the effect of modification on the bamboo microstructure and functional groups. In the context of SEM, TGA, and FTIR analyses, the thermal stability of bamboo modified with a medium or high concentration of DMDHEU was improved, the starch granules in the parenchyma cells of modified bamboo dissolved, and few resins were distributed in the lumens of treated bamboo. [ABSTRACT FROM AUTHOR]

This study evaluates the effect of 1% to 5% NaOH treatments of cotton stalk particles on the chemical composition and physical and mechanical properties of particleboards produced with this material. Gas chromatography and Fourier transform infrared (FTIR) spectroscopy indicated that the extractive, hemicellulose, and lignin content of the particles decreased during the alkali treatments, whereas the cellulose content increased. Thermogravimetric analysis (TGA) indicated that the untreated particles exhibited higher thermal stability than the particles treated with NaOH. The decrease in thermal stability of alkali-treated particles seems to be due to degradation of chemical components. Alkali treatments raised water absorption (WA) and thickness swelling (TS) of the produced particleboards. Except for 1% NaOH, the treatments reduced the modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond (IB) strength in relation to the board made with untreated particles. The 1% NaOH treatment of cotton stalks was more effective and beneficial, leading to particleboards with satisfying MOE, MOR, and IB values that met the requirements for general-purpose particleboards used in dry conditions, as indicated by the TS-EN 312 (2012) standard. [ABSTRACT FROM AUTHOR]

As a high-strength biomass composite material, the development of bamboo scrimber (BS) was limited by its flammable characteristics. In this study, different immersion orders of ammonium polyphosphate (10 wt%, APP solution) for bamboo bundles were selected in order to evaluate its influence on the interphase behavior, mechanical and combustion properties of BS. The flattened bamboo bundles, phenol-formaldehyde (PF) and APP solution were utilized to fabricate the BSs. The interphase behavior of the treated bamboo bundles was characterized by the contact angle measurement, Fourier transform infrared spectroscopy (FTIR) analysis, fluorescence microscope and SEM-EDS measurement. Thermogravimetric analysis, limiting oxygen index (LOI), mechanical properties before and after combustion test were assessed for various BSs. The results showed that significantly increased equilibrium contact angle of PF droplet on the surface of bamboo after immersed in APP solution while the decrement was for APP solution droplet on the surface of bamboo after immersed in PF. Varied intensities of chemical bonds and distribution forms of APP and PF were observed for the treated BSs depending on the immersion orders. These variations have a great effect on the mechanical and combustion properties. No significant decrement of compressive strength and bending strength was observed for APP-treated BSs with different immersion orders compared with the control sample. Higher compressive strength, bending strength, and modulus of elasticity (MOE) were found for the APP-PF-BS with increments of 31.60%, 21.70%, and 29.01%, respectively. Significantly increased thermal stability was observed for bamboo bundles after immersed in APP and PF especially for the temperature over 300 °C. After the combustion test (duration of 40 min), a higher LOI of 35.4, retention rates of mechanical properties of 39.96–78.97%, and lower mass loss of 15.93% were obtained for the PF-APP-BS. Finally, the immersion order of low concentration of APP solution has a great effect on the interphase behavior, mechanical and combustion properties of BSs, which plays a significant role in the optimized fabrication of fire-resistant BSs. • Varied interphase behavior was observed for APP-treated bamboo and BSs. • No obvious decrease of compressive and bending strengths was for APP-treated BSs. • Significantly increased thermal stability was observed for APP-treated bamboo. • Better fire-resistant behavior was obtained for PF-APP-BS with higher LOI and lower mass loss. • Higher retention rates of mechanical properties of 39.96–78.97% were observed for PF-APP-BS. [ABSTRACT FROM AUTHOR]