Figure 4 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
An environmentally friendly liquefaction of wood powder was prepared by atmospheric pressure liquefaction technology to replace the non-renewable petroleum polyols in the preparation of polyurethane foam composites. The liquefaction time varied from 0 min to 140 min. The composition of liquefied products and the effects of liquefaction time on the...
Context in source publication
Context 1
... stretching vibration of C-O in lignin was 1264 cm −1 , and the asymmetric stretching vibration of C-O-C in cellulose was 1162 cm −1 . The absorption peak at 1110 cm −1 was caused by C-O-C symmetric stretching vibration, indicating that there are ether compounds in the liquefied products, which may come from the degradation of lignin, as shown in Figure 2, or the condensation reaction between liquefied solvents, as shown in Figure 4. The furan ring skeleton vibration at 990 cm −1 may be the product of cellulose degradation by PEG 400. ...
Citations
... This was directly related to the use of a polyol derived from the liquefaction of lignocellulosic biomass, which presented a higher hydroxyl index than the one from the industrial polyol. In fact, authors contributing to the literature have already reported that higher values of the hydroxyl index usually lead to an incremented density of the polyurethane foams [77,78]. This is because a high hydroxyl number provides a higher degree of crosslinking of the PUF [79]. ...
In this work, biobased rigid polyurethane foams (PUFs) were developed with the aim of achieving thermal and fireproofing properties that can compete with those of the commercially available products. First, the synthesis of a biopolyol from a wood residue by means of a scaled-up process with suitable yield and reaction conditions was carried out. This biopolyol was able to substitute completely the synthetic polyols that are typically employed within a polyurethane formulation. Different formulations were developed to assess the effect of two flame retardants, namely, polyhedral oligomeric silsesquioxane (POSS) and amino polyphosphate (APP), in terms of their thermal properties and degradation and their fireproofing mechanism. The structure and the thermal degradation of the different formulations was evaluated via Fourier Transformed Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). Likewise, the performance of the different PUF formulations was studied and compared to that of an industrial PUF. From these results, it can be highlighted that the addition of the flame retardants into the formulation showed an improvement in the results of the UL-94 vertical burning test and the LOI. Moreover, the fireproofing performance of the biobased formulations was comparable to that of the industrial one. In addition to that, it can be remarked that the biobased formulations displayed an excellent performance as thermal insulators (0.02371–0.02149 W·m−1·K−1), which was even slightly higher than that of the industrial one.
... The green chemical pathway of polyurethane synthesis is a promising environmentally friendly process for wood modification (Wołosz et al. 2022). Non-isocyanate route of polyurethane synthesis based on the reactivity of the cyclic carbonate group with amines has been patented by Bernard (2008) and it has been mostly applied to produce polyurethane foams (Heck et al. 2015;Hu et al. 2012;Saldaev et al. 2018;Yang et al. 2021;Zhao et al. 2012). Even though in-site synthesis of poly(hydroxy)urethanes was thought beneficial for cell wall modification, it was realized challenging to gain a high degree of polymerization of polymers through aqueous phase and two-step impregnations of di-carbonate monomers with di-or tri-amines, probably because of the difficulty to control the stoichiometry during impregnation precisely (Brossier et al. 2021;Iaych 2010). ...
A non-isocyanate route of polyurethane synthesis based on polyol (xylitol, sorbitol, glycerol, and PG3), alkyl carbonate (DMC and DEC), and diamine (HMDA, EDA, and DETA) was conducted for wood impregnation through in-site polymerization. The structure and mass average molecular weight (Mw) of the polyurethanes were analyzed using FTIR, NMR, and SEC. According to the results, polyurethane synthesis by a two-pot method in water brought cyclic carbonate degradation. The distribution of Mw of the polyurethanes showed that the most satisfying polymer (4380 g/mol) was prepared without solvent. Polyurethanes synthesized in methanol have a higher Mw than that in distilled water. In the same solvent, the use of HMDA resulted in a polymer with higher Mw than that of EDA. One-step wood impregnation in a solvent gave unsatisfactory WPG (12.59–19.71%) and LC (50.36–62.80%). However, one-step impregnation without solvent gave a higher WPG (78.39–87.63%) and a lower LC (19.11–21.25%). It is not feasible to be applied industrially. The two-step impregnation gave WPG (14.89-30.73%) and LC (42.22–56.52%). Wood impregnation using methanol or ethanol as the solvent was more recommended than using an aqueous solution. However, the resistance against leaching needs improvement.
Keywords: Alkyl carbonate, diamine, polyol, polyurethane, wood impregnation
... As expected, the liquefaction reaction time has an influence on the mechanical properties of the resulting foams through the molecular weight of the obtained polyols. Recently, an intense variation of the polyol molecular weights with the liquefaction reaction time was observed [95]. The molecular weights of the polyols are dependent on the reaction parameters (time) ( Table 4). ...
... The relative molecular weights of the liquefied products at different liquefaction times[95]. ...
One of the main strategies for sustainable human society progress is the development of efficient strategies to limit waste production and maximize renewable resource utilization. In this context, this review highlights the opportunity to transform vegetable biomass residues into valuable commercial products. Biomass conversion entails the depolymerization of lignocellulosic biomass towards biopolyols and the synthesis and characterization of the valuable products obtained by using them. The influence of the reaction parameters in both acid and basic catalysis is highlighted, respectively the influence of microwaves on the liquefaction reaction versus conventional heating. Following the depolymerization reaction, polyols are employed to produce polyurethane foams. As a special characteristic, the addition of flame-retardant properties was emphasized. Another interesting topic is the biodegradability of these products, considering the negative consequences that waste accumulation has on the environment.
... Conventional polyurethane raw materials, such as polyether and polyester polyols, are petroleum-dependent products, which considerably limit their sustainable development [33][34][35][36]. The Earth's crust contains over 90 elements, with O and Si accounting for approximately 49% and 26% of the total abundance of these elements, respectively [37]. ...
Polysiloxanes have attracted considerable attention in biomedical engineering, owing to their inherent properties, including good flexibility and biocompatibility. However, their low mechanical strength limits their application scope. In this study, we synthesized a polysiloxane-based polyurethane by chemical copolymerization. A series of thermoplastic polysiloxane-polyurethanes (Si-TPUs) was synthesized using hydroxyl-terminated polydimethylsiloxane containing two carbamate groups at the tail of the polymer chains 4,4′-dicyclohexylmethane diisocyanate (HMDI) and 1,4-butanediol as raw materials. The effects of the hard-segment content and soft-segment number average molecular weight on the properties of the resulting TPUs were investigated. The prepared HMDI-based Si-TPUs exhibited good microphase separation, excellent mechanical properties, and acceptable repeatable processability. The tensile strength of SiTPU-2K-39 reached 21.5 MPa, which is significantly higher than that of other flexible polysiloxane materials. Moreover, the tensile strength and breaking elongation of SiTPU-2K-39 were maintained at 80.9% and 94.6%, respectively, after three cycles of regeneration. The Si-TPUs prepared in this work may potentially be used in gas separation, medical materials, antifouling coatings, and other applications.
