“…Figure 4 a shows that the intensity band at 3342 cm −1 corresponds to the stretching or axial deformation of the hydroxyl groups (OH) bound to the cellulose structure 40 . The bands detected around 2921 cm −1 and 2847 cm −1 for both samples are correlated with CH stretching of the methylene (CH 2 ) and methyl (CH 3 ) groups from polysaccharides compound 41 . Figure 4 Infrared spectra of the piassava fibers ( a ) untreated and ( b ) treated with NaOH 10%.…”
The use of castor oil in producing polyurethane resins has been identified as one of the most promising options for the industry. The piassava fibers waste generated by the industry on a large scale presents excellent properties as a reinforcing agent due to its high lignin content characterized by chemical tests and FTIR. Composite boards consisting of a higher content of mercerized piassava fibers (10 mm, 85 wt.%) reinforced polyurethane castor oil-based resin (prepolymer (PP) and polyol (OM)) exhibited excellent performance. Composites with these properties have strong potential for medium-density applications ranging from biomedical prosthetics to civil partition walls and insulation linings. Alkali treatment removed the superficial impurities of piassava fibers, activating polar groups, and physical characterization reported excellent performance for all composites. Among the composites, the CP3 sample (composite reinforced with piassava fibers (85 wt.% fibers; 1.2:1—PP:OM)) stood out with higher density and lower swelling and water absorption percentage than other composites. FTIR results indicated NCO traces after the resin cured in the PU3 (1.2:1—PP:OM), possibly contributing to the interaction with the fibers. DMA results reported relevant information about more flexibility to CP1 (composite reinforced with piassava fibers (85 wt.% fibers; 0.8:1—PP:OM)) and CP3 than CP2 (composite reinforced with piassava fibers (85 wt.% fibers; 1:1—PP:OM)). The results suggest that the proper combination with natural products must lead to composites with potential applications as engineering materials.
“…Figure 4 a shows that the intensity band at 3342 cm −1 corresponds to the stretching or axial deformation of the hydroxyl groups (OH) bound to the cellulose structure 40 . The bands detected around 2921 cm −1 and 2847 cm −1 for both samples are correlated with CH stretching of the methylene (CH 2 ) and methyl (CH 3 ) groups from polysaccharides compound 41 . Figure 4 Infrared spectra of the piassava fibers ( a ) untreated and ( b ) treated with NaOH 10%.…”
The use of castor oil in producing polyurethane resins has been identified as one of the most promising options for the industry. The piassava fibers waste generated by the industry on a large scale presents excellent properties as a reinforcing agent due to its high lignin content characterized by chemical tests and FTIR. Composite boards consisting of a higher content of mercerized piassava fibers (10 mm, 85 wt.%) reinforced polyurethane castor oil-based resin (prepolymer (PP) and polyol (OM)) exhibited excellent performance. Composites with these properties have strong potential for medium-density applications ranging from biomedical prosthetics to civil partition walls and insulation linings. Alkali treatment removed the superficial impurities of piassava fibers, activating polar groups, and physical characterization reported excellent performance for all composites. Among the composites, the CP3 sample (composite reinforced with piassava fibers (85 wt.% fibers; 1.2:1—PP:OM)) stood out with higher density and lower swelling and water absorption percentage than other composites. FTIR results indicated NCO traces after the resin cured in the PU3 (1.2:1—PP:OM), possibly contributing to the interaction with the fibers. DMA results reported relevant information about more flexibility to CP1 (composite reinforced with piassava fibers (85 wt.% fibers; 0.8:1—PP:OM)) and CP3 than CP2 (composite reinforced with piassava fibers (85 wt.% fibers; 1:1—PP:OM)). The results suggest that the proper combination with natural products must lead to composites with potential applications as engineering materials.
“…The Figure 4a shows the intensity band at 3342 cm -1 corresponds to the stretching or axial deformation of the hydroxyl groups (OH) bound to the cellulose structure [38]. The bands detected around 2921 cm -1 and 2847 cm -1 for both samples are correlated with CH stretching of the methylene (CH 2 ) and methyl (CH 3 ) groups from polysaccharides compound [39].…”
The intensive global environmental changes have motivated researchers to follow new routes to reuse or recycle waste. Castor oil for producing polyurethanes is one of the most viable routes for resin production. This study combined castor oil resin-based with the piassava fibers waste generated by the industry. Higher content of mercerized piassaba fibers (10 mm, 85 wt.%) reinforced polyurethane castor oil-based resin, resulting in composite boards. Characterizations included FTIR, TGA, DSC, FTIR, DMA, and SEM analyses. Piassaba fibers, after alkaline treatment, present excellent performance reported by physical characterization for all composites, highlighting the CP3 sample with higher density and lower swelling and water absorption percentage than other composites. FTIR results indicated NCO traces after the resin cured in the PU3, possibly contributing to the interaction with the fibers. DMA results reported relevant information about more flexibility to CP1 and CP3 than CP2. This study suggests that the proper combination with natural products must lead to composites with potential applications as engineering materials.
“…There is more residual coal in a goaf due to increased mining intensity, coupled with severe air leakage, raising the possibility that the residual coal self-ignites. The spontaneous combustion of coal can lead to huge economic losses [4]. Therefore, the mechanism underlying the spontaneous combustion of coal must be investigated in order to guarantee the safety of coal mine production [5,6].…”
In order to study the effect of hydrated phase change materials on the suppression of spontaneous combustion in coal, a thermogravimetric experiment and a reaction activation energy analysis experiment were conducted to explore the changes in the combustion characteristic parameters, characteristic temperature, and activating energy of gas coal, long-flame coal, meagre coal, and lean coal before and after adding hydrated phase change materials. The research results indicated that hydrated phase change materials increased the characteristic temperature point of the coal samples and had effective inhibitory effects on different stages of the oxidation process. However, the effect was best at low temperatures, as hydrated phase change materials undergo phase change and absorb heat when heated at low temperatures, isolating coal from contact with oxygen. The activating energy increased by 1.138–23.048 KJ·mol−1 and the mass loss was reduced by 1.6%–9.3% after inhibition of the coal samples, indicating that the oxidation rate of the various coal samples was slowed down and, thus, spontaneous combustion can be suppressed through the use of hydrated phase change materials. At the same time, this material reduced the combustibility indices of meagre coal and lean coal, as well as the comprehensive combustion indices of long-flame coal and gas coal.
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