Structural Analysis of Lignin-Based Furan Resin

The global “carbon emission peak” and “carbon neutrality” strategic goals promote us to replace current petroleum-based resin products with biomass-based resins. The use of technical lignins and hemicellulose-derived furfuryl alcohol in the production of biomass-based resins are among the most promising ways. Deep understanding of the resulting resin structure is a prerequisite for the optimization of biomass-based resins. Herein, a semiquantitative 2D HSQC NMR technique supplemented by the quantitative 31P NMR and methoxyl group wet chemistry analysis were employed for the structural elucidation of softwood kraft lignin-based furfuryl alcohol resin (LFA). The LFA was fractionated into water-insoluble (LFA-I) and soluble (LFA-S) parts. The analysis of methoxyl groups showed that the amount of lignin was 85 wt% and 44 wt% in LFA-I and LFA-S fractions, respectively. The HSQC spectra revealed the high diversity of linkages formed between lignin and poly FA (pFA). The HSQC and 31P results indicated the formation of new condensed structures, particularly at the 5-position of the aromatic ring. Esterification reactions between carboxyl groups of lignin and hydroxyl groups of pFA could also occur. Furthermore, it was suggested that lignin phenolic hydroxyl oxygen could attack an opened furan ring to form several aryl ethers structures. Therefore, the LFA resin was produced through crosslinking between lignin fragments and pFA chains.

MOLECULAR DYNAMICS SIMULATIONS OF FURAN RESIN (POLYFURFURYL ALCOHOL): PREDICTING MECHANICAL PROPERTIES

Furan resins can be used as precursor resin for Carbon-Carbon Composites but has also been used in adhesives, acid/corrosion resistant materials, and as an alternative fuel precursor [15]. This paper contains the most current understanding of the structure of furan resin and a Molecular Dynamics workflow for computationally simulating its polymerization with the 'fix bond/react' command implemented in LAMMPS. The predicted mechanical properties of the polymerized resin are in good agreement with the literature values.

Research on the Release of Dangerous Compounds from the BTEX and PAHs Groups in Industrial Casting Conditions

The assessment of the harmfulness of moulding and core sands is mainly based on investigations of compositions of gases emitted by liquid casting alloys during the mould pouring. The results of investigations of moulding sands obtained under industrial conditions are presented in this paper. A unique research stand was designed and built for this aim. It allowed us to determine emissions of gases at individual stages of casting a mass up to 50 kg. This approach enables simulation of foundry conditions. Moulding sands bound by organic binders (phenol-formaldehyde; furan), inorganic binders and green sand, were subjected to investigations. The composition of gases that evolved during the individual stages, pouring, cooling and knocking out, was tested each time, and the contents of Polycyclic Aromatic Hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and xylenes (BETX) were analysed. Investigations indicated that the emission of gases from sands with inorganic binders is negligible when compared with the emission of gases from sands with organic binders. The emission of gases from green sand is placed in the middle of the scale. As an example: the sand with furan resin emitted 84 mg of BTEX (in recalculation for 1 kg of sand) while from sands with inorganic binders there was a maximum of 2.2 mg (for 1 kg of sand). In the case of sands with inorganic binders, MI and MC sands indicated comparable and very low emissions of gases from the PAHs group, at the level of 0.018 mg and 0.019 mg for 1 kg of sand, respectively. The higher emission of PAHs from MG sand is the result of its different way of hardening (a binder was of an organic character) than of sands MI and MC.

Effect of Different Gating Systems and Sand Mold Binder on the Cast-Quality of Bicycle Frame Produced through Sand Casting Method

The bicycle frame produced through the metal casting process by recycling aluminum alloys can be an environmentally friendly alternative solution. Mold types and gating systems used generally affects the quality of the casting product. In this experiment, the effect of gating number and riser type variations (for sand binder) observed on casting defects, hardness, and impact value. Subsequently, chemical composition and microstructure of recycled aluminum metal from bicycle frames produced through sand mold casting are also evaluated. Three types of risers are bentonite, water glass, and furan resin. The results indicate that mold with two gating system has a low porosity as casting defects. The cast-bike frame produced using furan resin reaches the highest hardness value of 46 HRB compared to water glass and bentonite as the binder of sand-molds. The impact test observes 3.9 J carried out by the ASTM E23 sample at room temperature.

Preparation and Characterization of Furan–Matrix Composites Blended with Modified Hollow Glass Microsphere

In this study, a new class of thermal insulation composites was prepared by blending a modified hollow glass microsphere (HGM) with furan resin. The particle dispersion between the microparticles and resin matrix was improved using 3-methacryloxypropyltrimethoxy silane (KH-570). Furthermore, the structure and morphology of the modified HGM were characterised by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). In addition, the effects of the modified HGM on the thermal insulation, flame retardancy, and thermal properties of the composites were investigated. The thermal conductivity of the composites was lower than that of the native furan resin. The minimum thermal conductivity of the composites was 0.0274 W/m·K; the flame retardancy of the composites improved, and the limiting oxygen index become a maximum of 31.6%, reaching the refractory material level. Furthermore, the thermal analysis of the composites demonstrated enhanced thermal stability. This study demonstrates that the composite material exhibited good thermal insulation performance and flame retardancy and that it can be applied in the field of thermal insulation.

CHARACTERISTICS INVESTIGATION OF PREPARED PLOYFURFURAL THROUGH THE POLYMERIZATION PROCESS

Recently, furfural is the most commonly produced industrial chemical because of its production is very flexible. In this study, furfural was converted into ploy furfural through polymerization process under acidic medium. Some mechanical and thermal characteristics were investigated for the viscous polymer. The polymer was characterized by the FTIR spectrum of the furan resin prepared in this study showed several bands due to the furan ring, which appears at (3116,1508,1149 and 735) cm-1. In addition, the spectrum showed a band at 3450 cm-1 due to the hydroxyl group and band at 1714 cm-1 due to carbonyl group which was generated by cleavage the furan ring under polymerization at the acid medium.The CHN analysis, curing condition of the polymer, was followed by the DSC technique, and the glass transition temperature of cured resin was an estimate (246 °C). Thermo Gravimetric Analysis (TGA) provides a good approach to accelerate the polymer lifetime testing that monitors weight changes in materials. The TGA and DSC of the furan resin compounds afterheating at 250 °C, 300 °C, 350 °C, and 400 °C; had one decomposition step. On the other hand, thermal treatment of polymer was done at different temperatures and times, and several thermal parameters were determined.

Mechanical Properties of Unidirectional Flax Fabric-Reinforced Furan Composites: Effect of Alkaline Treatment and Silane Coupling Treatment

Composite materials based on bio-derived furan resin and natural fiber as reinforcing elements were studied. The purpose of this research is to improve the mechanical properties of this composite material by focusing on the natural fiber treatment methods. Unidirectional flax fabric was pretreated by alkaline treatment, silane coupling treatment, and the combination between alkaline and silane treatment before impregnating with furan resin. Three-point bending test, SEM observation, and ATR-IR analysis were carried out to evaluate the effects of treatment methods on the composite samples. Results reveal that the flexural strength of the composite was increased to 215MPa, 232MPa, 247MPa for alkaline, silane, and alkaline-silane treated composites respectively while the flexural strength of the untreated composite sample is 200MPa. SEM images show the effects of alkaline treatment on a single flax fiber at different treatment durations. The coupling of silane on the surface of flax fiber was confirmed by ATR-IR.