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A special medium-density fiberboard (MDF) has been fabricated in order to electromagnetic shielding composite by adding iron oxide nanoparticles (NF) to wood fiber (WF). The aim of this work was to study the panel properties with different loadings (1, 3, 5, 7, and 10 wt %) of Fe3O4 nanoparticles. The mechanical, physical, and Electromagnetic (EM) shielding properties of the produced fiberboard were analyzed. The maximum shielding effectiveness (SE) was 13.6 dB for the NF10 in the frequency range of 8.2–12.4 GHz and the absorption had the main contribution to the SE of the panels rather than the reflection. Internal bonding (IB) of the MDF panel was increased by 8.5% by adding 1% Fe3O4 nanoparticles. After that, the IB decreased compared to the control one. The modulus of rupture (MOR) and modulus of elasticity (MOE) of the MDF panels were less than the control panel. The MOR, MOE, IB, thickness swelling (TS), and water absorption (WA) of the panel with 10% Fe3O4 nanoparticles (NF10) panel showed 21.5, 2489, 0.56 MPa, 13.4%, and 61.4%, respectively. Generally, the fiberboard fabricated with 10% Fe3O4 nanoparticles indicated the ability for Electromagnetic shielding applications because of their acceptable properties according to the EN622-5 standard and appropriate EM shielding. [ABSTRACT FROM AUTHOR]

Polyols are groups of organic compounds which contain carbon and are randomly linked to other atoms, especially carbon-carbon and carbon-hydrogen. These compounds are mainly used as reactants to make other polymers. Among biopolymers, lignin is regarded as the base of a new polymer in polyol construction. The present study aimed to investigate the effects of amine type (diethylenetriamine and ethylenediamine) on the modification of lignin-based polyols, so as to provide an alternative to petroleum polyols and, in turn, increase functional groups and reduce their harm to humans' health and the environment. To this aim, first, lignin was extracted from raw liquor. Next, the extracted lignin was reacted with diethylenetriamine (DETA) and ethylenediamine (EDA). Finally, the Mannich method was used for the reaction between amine lignin and propylene carbonate. The results of the Fourier Transform Infrared (FTIR) spectroscopy analysis showed that modification with DETA led to more structural change in lignin and peak 1100 indicates the presence of C-O bond related to urethane bonds in modified lignin. Moreover, adding propylene carbonate to aminated lignin did not result in much change in the results of the FTIR analysis. Additionally, urethane bonds can be seen in the results of GPC at 400°C-500°C. Furthermore, a slight decrease in thermal stability was observed in lignin modified with amine and propylene carbonate, compared to the raw lignin sample. [ABSTRACT FROM AUTHOR]

This research used an oven and sprays drying method to dry nanofibrillated cellulose (NFC) and evaluates its effect on polylactic acid (PLA) nanocomposite properties. As shown by atomic force microscopy (AFM), the average size of nanocellulose in the spray-dried sample (NCSD) was 84-96 nm. However, the average size of nanocellulose obtained from oven drying was 647-697 μm. The average size of the NCSD sample indicates that spray drying kept nanocellulose in the nano-scale range after drying. A melting process was then used to reinforce the polylactic acid matrix with the spray and oven-dried nanocellulose. Compared to neat PLA and PLA-containing oven-dried forms of nanocellulose (PLA-NCOD), our results showed a significant improvement in the mechanical strength of nanocomposites containing PLA-NCSD. PLA-NCSD nanocomposite demonstrated greater thermal stability than neat PLA and PLA-NCOD when subjected to thermal analysis. This study clearly illustrates the comparative effect of spray-dried nanocellulose on reinforced nanocellulose/PLA composites. [ABSTRACT FROM AUTHOR]

In order to protect the environment and cellulose resources, yarn wastes from the textile industry, which contains a considerable amount of cellulose, can be used to produce microcrystalline cellulose. In this study, yarn waste was milled via a ball mill and was subjected to acid hydrolysis using sulfuric acid and hydrochloric acid at different times. It was characterized through various tests to determine the particle size, degree of polymerization, bulk and tap density, water soluble substances, ash content, moisture absorption capacity, infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. The Fourier-transform infrared spectroscopy analysis showed that the chemical compositions of all the samples were the same. The X-ray diffraction measurement showed an increase in crystallinity after acid hydrolysis. The thermogravimetric analysis showed that prepared microcrystalline cellulose via acid hydrolysis had good temperature resistance. The results obtained showed that the cotton waste from textiles was able to produce cellulose microcrystalline at a pharmacy standard level. [ABSTRACT FROM AUTHOR]

The main purpose of this work was to study the formaldehyde emission from wood plastic composites (WPCs) containing polyvinyl chloride (PVC), wood flour, and sanding dust of medium density fiberboard (MDF). Wood floor was replaced with 10, 15, and 20% MDF sanding dust (as a wood‐based panel waste), and the composites were manufactured by the extrusion method. Formaldehyde emission from WPCs was measured using two different methods: the desiccator method according to ISO 12460 and the flask method according to EN717‐3. Moreover, the physical and mechanical properties of the WPC samples were determined. The results indicated that the use of MDF sanding dust in formulation of WPCs leads to higher formaldehyde emission. The composites with higher content of MDF sanding dust exhibited higher formaldehyde emission. Although the PVC composites containing MDF sanding dust release formaldehyde, the formaldehyde emission values were very low. Therefore, these composites can be considered to be green composites and there is no concern in their indoor applications. J. VINYL ADDIT. TECHNOL., 25:159–164, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Polyols, which are important compounds of polyurethane adhesives (PU), were prepared in this work from renewable sources. Beech wood sawdust was liquefied using ethylene carbonate as a new solvent and sulfuric acid as a catalyst in the two phases. The first phase of the liquefaction process was carried out at temperatures 110 to 160 °C, and the catalyst content was studied in the second phase. The biopolyol was used for two types of polyurethane adhesive by blending two types of isocyanate, poly4,4'-diphenyl methane diisocyanate (PMDI) and toluene diisocyanate (TDI), in different NCO/OH ratios for the preparation of polyurethane adhesives. Liquefaction temperature had a great influence on the characteristics of polyol such as acid and hydroxyl numbers and yield. Moreover, the polyol obtained at 130°C and 120 min with yield 85% was found to be a suitable polyol for preparing polyurethane adhesives. By increasing the molar ratio (NCO/OH) to 1.7, the lap shear strength was increased. The optimal lap shear strengths in PU PMDI and PU TDI were 1.64MPa and 1.46MPa, respectively. FTIR results showed that due to the presence of hydroxyl groups (OH), beechwood sawdust can be a source of polyol. Urethane bonds can form between the polyol and isocyanate in polyurethane adhesives. [ABSTRACT FROM AUTHOR]

The goal of this research was improving the mechanical and physical properties of poly lactic acid (PLA) using cellulose nanofiber (CNF) as reinforcing and maleated PLA (PLA-g-MA) as a compatibilizer. PLA/nanocellulose composites were prepared through melt mixing with maleated PLA (5 wt%) and two levels of cellulose nanofibers (CNFs) (3 and 5 wt%) using twin screw extrusion. Nanocomposites fracture morphology, thermal properties, crystallization behavior, and mechanical behavior were determined as a function of cellulose nanofibers and PLA grafted on maleic anhydride content using scanning electron microscopy (SEM), atomic force microscopy, heat distortion temperature (HDT), impact, and tensile testing. The SEM micrographs confirmed the uniform dispersion of CNF within PLA matrix in the presence of maleated PLA. Among nanocellulose and compatibilizer, the latter one has better role in enhancement of nanocomposites HDT. Compatibilized nanocomposites (PLA/CNF5/PLAgMA5) exhibited maximum impact strength which was 131% higher than that of neat PLA. Compared to pure PLA, 138 and 40% improvements for the tensile strength and Young’s modulus can be obtained for the resulting nanocomposite with PLA/CNF5/PLAgMA5, respectively. [ABSTRACT FROM AUTHOR]

In this research, maleated poly(lactic acid) (PLA-g-MA) was manufactured by different levels of maleic anhydride (MAH). Also PLA-g-MA effects as a compatibilizer were investigated on PLA/cellulose nanofiber (CNF) composites. The grafting reaction was performed in the presence of dicumyl peroxide (DCP) as an initiator at constant level (0.2 phr) via reactive extrusion. Furthermore, the effects of four different levels of MAH (1–4 phr) were studied on the physical properties of PLA grafted films. We used the Fourier transform infrared (FTIR) and titration methods for confirmation of the grafting process. Based on the titration method, the greatest amount of yield was gained by 4 phr of MAH in grafting. Contact angle analysis shows that increasing the amount of MAH led to a decrease in the contact angle of films. Moreover, the glass transition temperature (Tg) and % crystallinity were decreased by increasing MAH content. PLA-g-MA was added to the composites in two levels of 3% and 5% in total. CNF was used at a constant level of 5%. The thermal, morphological and mechanical properties of nanocomposites were determined as a function of PLA-g-MA content using thermogravimetric analysis, heat distortion temperature (HDT) and tensile testing. All the prepared nanocomposite materials showed improvement in the mechanical and thermal properties compared to neat PLA. [ABSTRACT FROM AUTHOR]

Present paper examines the effect of acid type and hydrolysis conditions on morphology, size, yield and crystallinity of produced cellulose nanocrystal (CNC). Cellulose obtained from waste office paper was hydrolyzed under the same conditions by Maleic acid (MA) and Sulfuric Acid (SA) in separate treatments. Also this cellulose was hydrolyzed under different timing and temperature by MA and SA. Results showed that produced cellulose nanocrystals have different size, yield and crystallinity under same conditions by MA and SA. MA treatment resulted in higher crystallinity, yield, and disperse solution. Therefore, MA was appeared superior to SA. Based on results the characteristics of nanocrystals are not only depended on hydrolysis conditions, but also on acid type. [ABSTRACT FROM AUTHOR]

In this research, the influence of nanoclay on urea–glyoxalated lignin–formaldehyde (GLUF) resin properties has been investigated. To prepare the GLUF resin, glyoxalated soda baggase lignin (15 wt%) was added as an alternative for the second urea during the UF resin synthesis. The prepared GLUF resin was mixed with the 0.5%, 1%, and 1.5% nanoclay by mechanically stirring for 5 min at room temperature. The physicochemical properties of the prepared resins were measured according to standard methods. Then the resins were used in particleboard production and the physical and mechanical properties of the manufactured panels were determined. Finally, from the results obtained, the best prepared resin was selected and its properties were analyzed by differential scanning calorimetry (DSC), Fourier transform infrared spectrometry (FTIR), and X-ray diffractometry (XRD). Generally the results indicated that the addition of sodium-montmorillonite (NaMMT) up to 1.5% appears to improve the performance of GLUF resins in particleboards. The results also showed that nanoclays improved mechanical strength (modulus of elasticity (MOE), Modulus of Rupture (MOR), and internal bond (IB) strength) of the panels bonded with GLUF resins. The panels containing GLUF resin and nanoclay yielded lower formaldehyde emission as well as water absorption content than those made from the neat GLUF resins. XRD characterization indicated that NaMMT only intercalated when mixed with GLUF resin. Based on DSC results, the addition of NaMMT could accelerate the curing of GLUF resins. The enthalpy of the cure reaction (ΔH) of GLUF resin containing NaMMT was increased compared with neat GLUF resin. Also the results of FTIR analysis indicated that addition of NaMMT change the GLUF resins structures. [ABSTRACT FROM PUBLISHER]