Bio‐based polyurethane foam, a new green environmental material, has attracted more and more attention of people. In this study, the tung oleic acid‐based polyurethane (TOPUF) had been prepared using ...one‐step method. Characterization of the polyurethane foams were carried out by SEM and Fourier transform infrared. The cell morphology, acoustic, and mechanical performance of TOPUF with different contents of tung oleic acid‐based polyols (TOAP) were studied and compared with that of a pure petroleum‐based polyurethane foam. In addition, the effects of thickness ratio of layers on the acoustic performance of the double‐layer composite polyurethane foam (DPUF) were also studied by means of theoretical model and experiment. The results illustrate that TOPUF shows a high absorption performance in the frequency range from 100 to 500 Hz and sound insulation performance in the range from 100 to 6300 Hz. The average sound absorption coefficient of TOPUF is 0.505, and the average transmission loss is 18.818 dB in this case. Furthermore, the average sound absorption coefficient and average transmission loss of DPUFs are 0.545 and 14.528 dB using multilayer structure. Overall, TOPUF has excellent acoustic properties and prodigious application prospects.
Lignin, nature’s dominant aromatic polymer, is found in most terrestrial plants in the range of 15–40% dry weight and provides structural integrity. Kraft lignin (KL) is a major by-product of pulp & ...paper industry where, hydrolysis lignin (HL) is the solid residue left from the enzymatic hydrolysis of wood after the pretreatment processes in cellulosic ethanol plants. Currently, most of the lignin is burned to generate heat and electricity and remaining is considered as a low value material. Only 1% of the annually produced lignin is being commercialized for its application in the preparation of bio-chemicals and to limited extent for bio-materials. Although with much lower reactivity, even crude lignin (a natural polyol) can be directly incorporated into polyurethane (PU) foam formulation due to the presence of aliphatic and aromatic hydroxyl groups in its structure as the reactive sites. However, bio-replacement ratios are usually low ~20–30% and further increasing replacement ratios results in fragile and low strength foams. Lignin depolymerization with selective bond cleavage is still a major challenge for converting it into value-added precursors especially for its utilization in the preparation of rigid PU foams. Depolymerization of these macromolecules can result in the valuable products with high hydroxyl number/functionality and low molecular weights, which in turn will increase the percentage replacement of bio-based polyols in the PU foam formulations. The technical routes/technologies for the depolymerization of lignins and their effective utilization as polyols in PU foams are summarized in this review article. These include direct utilization of lignin as well as the incorporation of depolymerized lignins, with and without modification, at high replacement ratios in PU foams. The major emphasis was given on the effective utilization of low value lignin for high value applications. Some of the associated challenges for the production of materials from lignin are also discussed.
Soccer is known as the world's largest sport and has a wide range of players. Most of the materials used in existing football equipment are polyurethane extracted from petrochemical resources, which ...are gradually reduced and non‐renewable. Finding an alternative new material is an inevitable trend. Soybean oil (SO) was quantitatively transformed into polyols to afford industrially important high resilience flexible polyurethane foam(HR‐PUF). Photoinduced thiol‐ene click chemistry was investigated for the efficient preparation of modified soybean oil polyols (MESO) with primary hydroxyl groups. In order to improve the reaction efficiency and the degree of carbon–carbon double bonds functionalization, reduce reaction time, we have chosen a step‐by‐step method of adding. The effects of different reaction times and thiol/ene ratios on conversion and degree of functionalization were discussed. It is realized that under room temperature conditions, after 12 h of reaction, the carbon–carbon double bond of SO is almost completely converted and quantitatively converted into a hydroxyl group to a degree of 89%. The corresponding HR‐PUFs were prepared by mixing MESO with L2000 (Polyether Polyol). The effect of the difference in the amount of MESO added to the foam properties was investigated. Through the apparent density and a scanning electron microscope (SEM), it can be concluded that with the amount of MESO added increases, the cell size, opening ratio and the number of cells of HR‐PUF are decreased, the density is increased. Through thermogravimetric analysis (TGA) and dynamic thermomechanical analysis (DMA), it was proved that the thermal stability of the foam increased with the addition of MESO. Through 40% compression strength (CLD40%), ball rebound experiments, and static compression experiment. It is proved that the increase of the addition of MESO, the rebound resilience of HR‐PUF can be improved.
The preparation route of HR‐PUF.
The building and construction industry is under increasing pressure to make insulation materials greener, more sustainable, and less flammable. In this study, sugar beet pulp was liquified under the ...optimized liquefaction conditions and used as the source of bio‐polyol (SBpol) in the production of bio‐based rigid polyurethane foam (sPUF). In order to improve the flame retardancy, sPUF composites were prepared with the addition of flame retardants; expandable graphite (EG) and/or dimethyl methyl phosphonate (DMMP). The bio‐polyol was used at a fixed ratio of 50 php in sPUF composites whereas the total ratio of flame retardants was fixed at 20 php. The effects of the ratio of EG and/or DMMP on the morphological, physicomechanical, thermal, and flame retardant properties of sPUF composites were evaluated. Although the thermal conductivity values of flame retardant added sPUF composites were increased in comparison to the petroleum‐based foam, the compressive strength values were decreased as the amount of DMMP increased in the flame retardant formulation. Thermogravimetric analysis showed that the onset of decomposition of 20 php DMMP‐containing sPUF composite decreased to 168.3°C. Although the limiting oxygen index (LOI) value of the petroleum‐based PUF was as low as 19.7%, the LOI value of the sPUF/10E/10D foam increased to 24.9% (by about 26%). According to the cone calorimeter results, the peak heat release rate (pHRR) of sPUF was much higher than the petroleum‐based foam. The incorporation of both DMMP and EG could further improve the flame retardant properties. The pHRR value of sPUF/10E/10D was 28.1% lower than that of sPUF. The results have shown that flame retardancy of sPUF composites could be improved by the addition of EG which acts in the condensed phase and DMMP, which acts mainly in the gas phase during burning. Flame retardant incorporated sPUF composites are considered as promising materials for use in insulation applications.
Sugar beet pulp polyol‐based rigid polyurethane foam composites as environmentally‐friendly insulation material.
Polymeric materials such as fabric and foam have high flammability which limits their application in the field of fire protection. To this end, an organic-inorganic polymer colloid constructed from ...carboxymethyl chitosan and ammonium polyphosphate was used to improve the flame retardancy of flax fabric (FF) and rigid polyurethane foam (RPUF) based on a “one for two” strategy. The modification processes of FF and RPUF relied on pad-dry-cure method and UV-curing technology, respectively, and the modified FF and RPUF were severally designated as CMC/APP-FF and RFR-RPUF. Flame retardancy studies showed that CMC/APP-FF and RFR-RPUF exhibited limiting oxygen index values as high as 39.4 % and 42.6 %, respectively, and both achieved self-extinguishing behavior when external ignition source was removed. Thermogravimetric analysis and cone calorimetry test confirmed that CMC/APP-FF and RFR-RPUF had good charring ability and demonstrated reduced peak heat release rate values of 90.1 % and 10.8 %, respectively, distinct from before they were modified. In addition, condensed phase analysis showed that after burning, CMC/APP-FF became an integration char structure, whereas RFR-RPUF turned into a sandwiched char structure. In summary, the “one for two” strategy reported in this work provides a new insight into the economical fabrication of flame-retardant polymeric materials.
•An organic-inorganic polymer colloid was constructed using CMC and APP.•The colloid gave flame retardancy to FF and RPUF based on a “one for two” strategy.•The modified FF and RPUF exhibited LOI values up to 39.4 % and 42.6 %, respectively.•The modified FF and RPUF formed two different char structures after combustion.
A reactive flame retardant hexa-(5,5-dimethyl-1,3,2- dioxaphosphinane-hydroxyl-methyl-phenoxyl)-cyclotriphosphazene (HDPCP) was synthesized by using 5,5-dimethyl-1,3,2-dioxaphosphinane 2-oxide and ...hexa-(4-aldehyde-phenoxy)-cyclotriphosphazene via P-H addition reaction. And it was used to prepare flame retardant rigid polyurethane foams (FR-RPUFs). The effect of flame retardant HDPCP on physical-mechanical, thermal degradation and fire behavior properties of FR-RPUFs system has been investigated. The results suggested that HDPCP showed no obviously negative influence on physical-mechanical property of RPUF. The thermal stability and char residue at 700 °C of RPUF were enhanced by introducing HDPCP. HDPCP is benefit to improve flame retardance of RPUF. The limiting oxygen index (LOI) increased from 19 to 25% with incorporation of 25% HDPCP. Moreover, the peak heat release rate (PHRR), total heat release rate (THR), total smoke rate (TSR) and total smoke production (TSP) of RPUFs decreased due to a good char-forming ability of HDPCP.
Kraft pine lignin was derivatized to a liquid polyol through oxypropylation. The resulting polyol was characterized by GPC, FT-IR, H¹, C¹³, and P³¹ NMR and was compared to commercial polyols in view ...of the mechanical property of the corresponding rigid polyurethane foams for the first time. A series of lignin-based PU was synthesized by replacing varying weight percentages of the amount of sucrose polyol and glycerol polyol, two commonly used commercial polyols employed in the control foam preparation. All foams had a low density of ∼30 Kg m⁻³ and showed typical linkages of PU in the FT-IR spectra. The diameter of closed-cells was ∼650 μm for most of the foams as revealed by SEM images. The optimal compressive property of rigid PU foams was obtained using lignin polyol without the addition of any other commercial polyols primarily attributed to the rigidity of lignin aromatic structure and the high functionality of lignin hydroxyl groups.
•phosphorous soybean-oil polyol applied in flexible polyurethane foams.•synergistic combination of phosphorous soybean-oil polyol and expandable graphite.•pyrolysis, flame retardancy and smoke ...suppression.
A phosphorous soybean-oil–based polyol was derived via epoxidation and ring opening reaction as an alternative to petrochemical-based polyol for the synthesis of flexible polyurethane foams (FPUFs). 5-wt.% and 10-wt.% of expandable graphite (EG) were added to further improve flame retardancy. The mechanical properties (tensile strength and compression stress) of the foams were investigated. Thermogravimetric analysis (TGA) coupled with Fourier-transform infrared (FTIR) were conducted to evaluate the pyrolysis; limiting oxygen index (LOI), UL 94 and cone calorimeter were performed to analyze the fire performance of the foams; smoke density chamber was used to investigate the smoke released during burning. When 10-wt.% of EG was used, the flame retardancy of the foams was much enhanced due to the synergistic effect between phosphorus and EG. The char yield was three times higher (54-wt.%). The fire load MARHE approached 100 kWm−2, half of the value expected for a superposition. The combination of phosphorous polyols and EG is proposed as strategy for future flame retarded FPUFs.
To enhance the flame-retardant performance of expandable graphite (EG) in rigid polyurethane foam (RPUF), EG particles were encapsulated with inorganic nanoparticles, namely aluminum hydroxide (ATH), ...forming complex particles EG@ATH with core-shell structure. After the deposition of ATH shell, the expandability of the particles was enhanced from 163 to 197 ml/g, leading to better flame-retardant performance in RPUF. At a content of 11.5 wt%, the limited oxygen index could be increased from 21.5% to 29.6% by EG@ATH, in comparison to 27.5% by the physical mixture of EG and ATH (EG + ATH). Besides, EG@ATH exhibited better performance than EG + ATH on reducing the total smoke release and CO production. It is worth noticing that ATH could react with isocyanate groups, which was confirmed through FTIR. As a result, the interaction between the core-shell particles and the polymer matrix was enhanced, which protected the cell structure of RPUF from destroying by EG particles. The improved flame-retardant performance of EG@ATH, together with their low-cost, easy fabrication and especially friendliness to the environment, make it prospective in applications for flame retardancy of RPUF.
A kind of core-shell expandable graphite @ aluminum hydroxide (EG@ATH) as the halogen-free flame retardant for rigid polyurethane foams (RPUF) was designed. This is the first report to prepare encapsulation of expandable graphite with inorganic nanomaterials to increase the expandability. The as-prepared EG@ATH particles showed high efficiency of flame retardancy in RPUF, and improved interface adhesion between EG@ATH particles and RPUF, due to the pre-reaction of ATH layers with polyisocyanate. Display omitted
