Synthesis of a boron modified phenolic resin Kawamoto, Aparecida M.; Pardini, Luiz Cláudio; Diniz, Milton Faria ...
Journal of aerospace technology and management,
08/2010, Volume:
2, Issue:
2
Journal Article
Peer reviewed
Open access
Phenolic resin has long been used as matrix for composites mainly because of its flame retardant behavior and high char yield after pyrolysis, which results in a self supporting structure. The ...addition of ceramic powders, such as SiC and B4C, as fillers to the phenolic resin, results in better thermo-oxidative stability, but as drawbacks, it has poor homogeneity, adhesion and processing difficulties during molding of the composites. The addition of single elements, such as boron, silicon and phosphorus in the main backbone of the thermo-set resin is a new strategy to obtain special high performance resins, which results in higher mechanical properties, avoiding the drawbacks of simply adding fillers, which results in enhanced thermo-oxidative stability compared to conventional phenol-formaldehyde resins. Therefore, the product can have several applications, including the use as ablative thermal protection for thermo-structural composites. This work describes the preparation of a boron-modified phenolic resin (BPR) using salicyl alcohol and boric acid. The reaction was performed in refluxing toluene for a period of four hours, which produced a very high viscosity amber resin in 90% yield.The final structure of the compound, the boric acid double, substituted at the hydroxyl group of the aromatic ring, was determined with the help of the Infrared Spectroscopy, 1H-NMR, TGA-DSC and boron elemental analysis. The absorption band of the group B-O at 1349 cm-1 can be visualized at the FT-IR spectrum. 1H-NMR spectra showed peaks at 4.97-5.04 ppm and 3.60-3.90 ppm assigned to belong to CH2OH groups from the alcohol. The elemental analysis was also performed for boron determination.The product has also been tested in carbon and silicon fibers composite for the use in thermal structure. The results of the tests showed composites with superior mechanical properties when compared with the conventional phenolic resin.
The main objective of these studies was the synthesis and characterization of new energetic binders and their use in some propellant formulations. Following the working plan elaborated, the synthesis ...and characterization of the following compounds has been done successfully: GAP; energetic Monomer BAMO; energetic Binders; copolymer GAP/PolyBAMO. The scale up for the synthesis of copolymer GAP/PolyBAMO and PolyBAMO using GAP as initiator has been done and they were fully characterized by IR, (1H, 13C) NMR-spectroscopy, GPC, elemental analysis, OH-functionality, differential scanning calorimetry (DSC) and sensitivity tests (friction, impact). For this two scale up synthesis some propellant formulations were carried out and the results of mechanical and burning properties have been compared with GAP propellants.
Thermal aging of hydroxy-terminated polybutadiene (HTPB) stabilized with 2,6-di(tert-butyl)hydroxytoluene (BHT) was carried out at 60ºC from 1 to 11 weeks. Samples of 200 mL were stored in sealed ...500-mL Erlenmeyer flasks under atmospheric pressure or vacuum and periodically withdrawn for physical and chemical analysis, infrared spectroscopy characterization and measurement of HTPB/IPDI (isophorone diisocyanate) reactivity, expressed as pot life. Mechanical properties of the cured polyurethane, prepared from aged HTPB, were assayed by uniaxial tension tests. Despite the unchanged chemical structure, an increase in HTPB/IPDI binder reactivity was observed, being correlated with BHT depletion measured as color change (yellowing). Aging of HTPB showed no interference on mechanical properties of the cured polyurethane.
Phenolic resin has long been used as matrix for composites mainly because of its flame retardant behavior and high char yield after pyrolysis, which results in a self supporting structure. The ...addition of ceramic powders, such as SiC and B4C, as fillers to the phenolic resin, results in better thermo-oxidative stability, but as drawbacks, it has poor homogeneity, adhesion and processing difficulties during molding of the composites. The addition of single elements, such as boron, silicon and phosphorus in the main backbone of the thermo-set resin is a new strategy to obtain special high performance resins, which results in higher mechanical properties, avoiding the drawbacks of simply adding fillers, which results in enhanced thermo-oxidative stability compared to conventional phenol-formaldehyde resins. Therefore, the product can have several applications, including the use as ablative thermal protection for thermo-structural composites. This work describes the preparation of a boron-modified phenolic resin (BPR) using salicyl alcohol and boric acid. The reaction was performed in refluxing toluene for a period of four hours, which produced a very high viscosity amber resin in 90% yield.The final structure of the compound, the boric acid double, substituted at the hydroxyl group of the aromatic ring, was determined with the help of the Infrared Spectroscopy, ¹H-NMR, TGA-DSC and boron elemental analysis. The absorption band of the group B-O at 1349 cm ˉ¹ can be visualized at the FT-IR spectrum. ¹H-NMR spectra showed peaks at 4.97-5.04 ppm and 3.60-3.90 ppm assigned to belong to CH2OH groups from the alcohol. The elemental analysis was also performed for boron determination.The product has also been tested in carbon and silicon fibers composite for the use in thermal structure. The results of the tests showed composites with superior mechanical properties when compared with the conventional phenolic resin.
Thermal aging of hydroxy-terminated polybutadiene (HTPB) stabilized with 2,6-di(tert-butyl)hydroxytoluene (BHT) was carried out at 60°C from 1 to 11 weeks. Samples of 200 mL were stored in sealed ...500-mL Erlenmeyer flasks under atmospheric pressure or vacuum and periodically withdrawn for physical and chemical analysis, infrared spectroscopy characterization and measurement of HTPB/IPDI (isophorone diisocyanate) reactivity, expressed as pot life. Mechanical properties of the cured polyurethane, prepared from aged HTPB, were assayed by uniaxial tension tests. Despite the unchanged chemical structure, an increase in HTPB/IPDI binder reactivity was observed, being correlated with BHT depletion measured as color change (yellowing). Aging of HTPB showed no interference on mechanical properties of the cured polyurethane.
This paper describes the action and results achieved during the optimization of Glycidyl Azide Polymer (GAP) characterization and process. Under different conditions, three different kinds of ...catalysts, BF3, SnCl4.5H2O and SnCl4 were used to obtain polyepichlorohydrin and each sample was converted into GAP. All the samples were submitted for characterization analysis by FT-IR and determination of molecular mass and hydroxyl value. Finally, results were compared and the best method to obtain GAP was determined.
The main objective of these studies was the synthesis and characterization of new energetic binders and their use in some propellant formulations. Following the working plan elaborated, the synthesis ...and characterization of the following compounds has been done successfully: • GAP; • energetic Monomer BAMO; • energetic Binders; • copolymer GAP/PolyBAMO. The scale up for the synthesis of copolymer GAP/PolyBAMO and PolyBAMO using GAP as initiator has been done and they were fully characterized by IR, (¹H, ¹³C) NMR-spectroscopy, GPC, elemental analysis, OH-functionality, differential scanning calorimetry (DSC) and sensitivity tests (friction, impact). For this two scale up synthesis some propellant formulations were carried out and the results of mechanical and burning properties have been compared with GAP propellants.
Resumo: Este trabalho descreve as ações e os resultados alcançados na otimização do processo de obtenção do pré-polímero MetilAzoteto de Glicidila (GAP). Foram obtidas amostras de poliepicloridrina ...(PECH) utilizando três diferentes catalisadores, BF3, SnCl4.5H20 e SnCl4 anidro, sob diferentes condições e cada amostrafoi convertida, posteriormente, no pré-polímero GAP. Cada uma das amostras foi submetida às análises por FT-IR, determinação do índice de hidroxila e determinação da massa molar. Ao final, os resultados obtidos foram comparados com os valores previamente estabelecidos e determinado o melhor método de obtenção do GAP.
SummaryGPC and VPO behaviours of HTPB samples have been examined in toluene employing polystyrene and polybutadiene standards. The results show that the molecular weights obtained depend on the ...nature of the calibration standards, particularly in the GPC analysis.
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