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Furfural (F) cannot be easily polymerized like furfuryl alcohol, but it is an aldehyde that can react with urea (U) to make a polymeric network. The possibility of preparing F/U polymer along with an acidic catalyzer (maleic anhydride; M) was evaluated as a means to improve some selected properties of birch (Betula pendula) wood. The F+U/M resin was introduced into the wood with a double treatment technology. The first step involved dilution of F in water and methanol, and the second step was immersion in a U/M aqueous solution. The color of treated wood was darkened after resin curing from brown to a spectrum of black depending on the amount of loaded resin. The 60 to 80% of materials were converted to a non-leachable polymer based on the different formulations. The water absorption and volumetric swelling of the treated samples decreased with an increase in weight percent gain (WPG). The analysis of mechanical strength showed that treatment with F + U/M reduced to some extent the hardness and the impact bending of wood, while modulus of rupture, modulus of elasticity, and compression parallel to the grain with WPG were increased. The exposure of the samples to the accelerated weathering showed noticeable changes in color and roughness.

The present work studied the possibility of using phthalimide for surface modification of cellulose nanofibers (CNF). The modification was carried out in 96/4 (v/v) water/acetic acid with CNF to phthalimide ratio of 1:0, 1:0.5, 1:1, and 1:1.5 wt%, respectively. Morphological, physical, chemical, and thermal properties of prepared aerogels were characterized by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction spectroscopy, and thermogravimetric analysis. The mechanical characterization such as the stress‐strain behavior was measured by compression testing. The results showed that surface modification and addition of phthalimide increased the surface area and pore volume but decreased the overall pores size. The presence of phthalimide onto CNF was confirmed by attenuated total reflectance‐Fourier transform infrared spectroscopy as the characteristic peaks of NH2, CN, and ester bonding ( COO−) appeared. Since more energy is needed for breaking hydroxyl bonds than ionic bonds, by taking into account the reduced hydrogen bonds as the result of the chemical modification, the thermal stability of the CNF‐Ph is lower than the pure CNF aerogel. Besides, the modulus of elasticity increased that could be due to the high densities.

To improve the heavy metal adsorption of microcrystalline cellulose (MCC), two successive grafting reactions of silylation by (3-chloropropyl)triethoxysilane (CPTES) and amine-functionalization with metformin HCl were performed and the modified MCC from the first and second steps were denoted as MMCC-1 and MMCC-2, respectively. MMCCs were characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) and compared to MCC. The presence of the amine group on the MMCC-2 surface was confirmed by FT-IR analysis. According to the XRD results, the crystallinity index (CI) of MMCC-1 increased very slightly compared to that of MCC that can be attributed to the partial hydrolysis of amorphous parts because of acidic conditions used for MCC silylation but CI of MMCC-2 decreased due to the high temperature and long time in the 2 nd step of modification. TGA revealed the lower thermal stability of MMCC-2 than the corresponding MCC.

Abstract: In this study, low density and high porosity aerogels were produced through freeze drying of cellulose nanofiber (CNF) dispersions with 0.6, 0.9 and 1.2 wt% concentration and modified via chemical vapor deposition (CVD) of hexadecyltrimethoxylan (HDTMS) to absorb and remove oil and organic pollutants from the water. Aergels were evaluated by density and porosity measurement, BET analysis, scanning electron microscopy, contact angle, oil absorption capacity and mechanical tests. The densities of unmodified and modified aerogels were in the range of 8.0–13.8 and 11–17.5 mg cm−3, respectively. The porosities of aerogels, before and after modification, were 99.1–99.5 and 98.8–99.3%, respectively. The porous structure formation via successful self assembling of CNF was also evidenced by the scanning electron microscopy images. All of the modified aerogels, regardless of the initial CNF concentration, had contact angle values greater than 90° and were classified as hydrophobic materials. The 0.6% sample revealed the highest adsorption capacities of 78.8 and 162.4 g g−1 for motor and cooking oils, respectively and the 1.2% aerogel exhibited the maximum values of stress and Young’s modulus in compression test. The results of this investigation indicated that ultra-light, hydrophob and superabsorbent materials based on chemically modified cellulosic aerogels with this type of silanated material were successfully produced. Graphical abstract: [Figure not available: see fulltext.]

Cellulose whiskers were isolated from kenaf (Hibiscus cannabinus L.) bast fibers via sulfuric acid and hydrochloric acid hydrolysis. Raw kenaf bast, NaOH treated, bleached fibers, sulfuric acid whiskers (SAW) and hydrochloric acid whiskers (HClW) morphology, functional groups, crystallinity, and thermal stability were characterized. The TEM images showed that the sulfuric acid and HCl whiskers have average diameters and length range of 3 nm and 100 - 500 nm, respectively. The FTIR study indicated that during the conversion process, most of the hemicellulose and almost all the lignin were removed by the NaOH and subsequent bleaching treatments. The crystallinity of HCl whiskers was found to be higher (84%) than that of sulfuric acid whiskers (72%). Thermogravimetric analysis indicated that HCl whiskers had better thermal stability than the sulfuric acid ones. In addition, a two-stage decomposition behavior was revealed by TGA in the sulfuric acid whiskers because of incorporation of the sulfate group with the cellulose crystals.

Environmental regulations, costs and lightweight encourage car manufacturers to develop new reliable products. Epoxy provides a reliable fibre impregnation and creates substantial three-dimensional (3D) cross-linking for proper load transmission and impact strength improvement, but their low toughness decreases their energy absorption. Thermoplastic toughening improves the epoxy impact property with a low thermo-mechanical defect. This study, focused on improving the impact property of hybrid kenaf/glass fibre epoxy composite by use of a modified sheet moulding compound (GMT). The results indicated that most of the mechanical properties of developed material were almost the same as those of the GMT, except impact. This result highlights the potential for utilisation of the toughened hybrid bio-composite in some automotive structural components. Moreover, geometric parameters, e.g., cross-section, thickness, and reinforcement ribs suggest an improvement of structural impact resistance to comply with the bumper beam product design specification (PDS).

Application of natural fibre composites is going to increase in different areas caused by environmental, technical and economic advantages. However, their low mechanical properties have limited their particular application in automotive structural components. Hybridizations with other reinforcements or matrices can improve mechanical properties of natural fibre composite. Moreover, geometric optimizations have a significant role in structural strength improvement. This study focused on selecting the best geometrical bumper beam concept to fulfill the safety parameters of the defined product design specification (PDS). The mechanical properties of developed hybrid composite material were considered in different bumper beam concepts with the same frontal curvature, thickness, and overall dimensions. The low-speed impact test was simulated under the same conditions in Abaqus V16R9 software. Six weighted criteria, which were deflection, strain energy, mass, cost, easy manufacturing, and the rib possibility were analyzed to form an evaluation matrix. Topsis method was employed to select the best concept. It is concluded that double hat profile (DHP) with defined material model can be used for bumper beam of a small car. In addition, selected concept can be strengthened by adding reinforced ribs or increasing the thickness of the bumper beam to comply with the defined PDS.

The present invention relates to a process for producing polylactic acid (PLA)- cellulose nanocomposite. The PLA-cellulose nanocomposite includes polymer matrix and cellulose nanofibers. The cellulose nanofibers having concentration of 1wt% to 5wt%. The cellulose nanofibers (CNF) are obtained from kenaf pulp. The cellulose nanofibers from kenaf pulp are reinforcing phase in PLA matrix. The cellulose nanofibers are kenaf nanofibers. The PLA-cellulose nanocomposite is produced using a two-step process: (i) preparing a pre-mixture of crushed CNF-films with PLA followed by (ii) compounding and extruding process.