“…These aforementioned remarks might give the knowledge that using these raw plant fibers in their pristine forms certainly would not lead to any enhancements in the targeted properties of the reinforced thermoplastic and/or thermosetting composites. Such observations were already reported by many researcher groups when they explored the impacts of the hemp fiber treatments on the properties of benzoxazine, 31 epoxy resin, 32 and cyanate ester/benzoxazine 33 resin composites. However, after being NaHCO 3 -treated, the fibers were recognized to possess a rough surface with some detected holes as clearly observed in Figure 4(b), indicating the removal of their essential compounds as stated in the FTIR, TGA studies.…”
Section: Resultssupporting
confidence: 59%
“…Similar observations were also reported in our previous investigation, when we investigated the influence of NaOH-treated hemp fibers on the structural properties of the resin blend. 33 To sum up, we postulated that the IR spectra investigations demonstrated that the NaHCO 3 -treated hemp fibers were linked with the resin blends. Figure 5.FTIR spectra of the DCBA/BA-a resin composites at: (a) 0 wt%, (b) 5 wt%, (c) 10 wt%, (d) 15 wt%, and (e) 20 wt% of treated hemp fiber contents.…”
Section: Resultsmentioning
confidence: 99%
“…This implied the possibility of establishing a great portion of OH groups from either the inter-molecular or the intra-molecular hydrogen (O-H…O) linking. 33 The formation of such interfacial bonding is perhaps very important because it possibly aids to obtain a good compatibility between the reinforcing fibers and the blend matrix, 31 as it has been discussed that the interphase (also known as the interface) plays the most critical role in materials-based composites, thus, the surface treatments of the reinforcing phase is of great importance for the final composite performances. Similar observations were also reported in our previous investigation, when we investigated the influence of NaOH-treated hemp fibers on the structural properties of the resin blend.…”
Section: Resultsmentioning
confidence: 99%
“…These outcomes were similar to the previous investigations regarding the effect of adding alkali-treated hemp fibers on the structural properties of the resin blend. 33 In addition, one could observe that the intensity in the region of 3400 cm À1 was progressively increased, which could be possibly due to the increase in the content of the hydroxyl groups generated from the NaHCO 3 and also to the chemical reaction (hydrogen bonding) taken place between the NaHCO 3 -treated hemp fibers and the blend matrix. 33 In other words, the broad transmittance band detected in the wavenumber of 3400 cm À1 could be possibly attributed to the formation of hydrogen bonding between the chemically modified fibers and the DCBA/BA-a resin matrix.…”
Section: Ftir Spectra Of the Pure Blend And The Filled Compositesmentioning
This present study details an experimental investigation on understanding the effects of surface-modified waste hemp fibers on the overall properties of thermosetting resin blends composed of dicyanate ester of bisphenol-A and bisphenol-A-based benzoxazine resins. At first, the hemp fibers were subjected to sodium bicarbonate treatment, and then various experimental tests in terms of the Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis tests were, respectively, carried out to understand the influence of the as-used treatment on the structural, morphological, and thermal properties of the hemp fibers. The obtained results from the surface characterization evidently demonstrated the positive sodium bicarbonate impacts on the properties of the hemp fibers. After that, various amounts of the treated fibers were incorporated within the dicyanate ester of bisphenol-A/bisphenol-A-based benzoxazine resin blends and the obtained composite materials were characterized for their structural, mechanical behavior and thermal properties. The obtained results clearly revealed that the prepared blend composites were identified to possess good bending and impact strength properties; however, a slight decline was observed in the thermal properties. The scanning electron microscopy and Fourier-transform infrared spectroscopy investigations demonstrated a good dispersion of the fibers within the blend matrix, and also an enhanced fiber–blend matrix interfacial adhesion, which were plausibly behind the improved mechanical properties of the prepared blend composites.
“…These aforementioned remarks might give the knowledge that using these raw plant fibers in their pristine forms certainly would not lead to any enhancements in the targeted properties of the reinforced thermoplastic and/or thermosetting composites. Such observations were already reported by many researcher groups when they explored the impacts of the hemp fiber treatments on the properties of benzoxazine, 31 epoxy resin, 32 and cyanate ester/benzoxazine 33 resin composites. However, after being NaHCO 3 -treated, the fibers were recognized to possess a rough surface with some detected holes as clearly observed in Figure 4(b), indicating the removal of their essential compounds as stated in the FTIR, TGA studies.…”
Section: Resultssupporting
confidence: 59%
“…Similar observations were also reported in our previous investigation, when we investigated the influence of NaOH-treated hemp fibers on the structural properties of the resin blend. 33 To sum up, we postulated that the IR spectra investigations demonstrated that the NaHCO 3 -treated hemp fibers were linked with the resin blends. Figure 5.FTIR spectra of the DCBA/BA-a resin composites at: (a) 0 wt%, (b) 5 wt%, (c) 10 wt%, (d) 15 wt%, and (e) 20 wt% of treated hemp fiber contents.…”
Section: Resultsmentioning
confidence: 99%
“…This implied the possibility of establishing a great portion of OH groups from either the inter-molecular or the intra-molecular hydrogen (O-H…O) linking. 33 The formation of such interfacial bonding is perhaps very important because it possibly aids to obtain a good compatibility between the reinforcing fibers and the blend matrix, 31 as it has been discussed that the interphase (also known as the interface) plays the most critical role in materials-based composites, thus, the surface treatments of the reinforcing phase is of great importance for the final composite performances. Similar observations were also reported in our previous investigation, when we investigated the influence of NaOH-treated hemp fibers on the structural properties of the resin blend.…”
Section: Resultsmentioning
confidence: 99%
“…These outcomes were similar to the previous investigations regarding the effect of adding alkali-treated hemp fibers on the structural properties of the resin blend. 33 In addition, one could observe that the intensity in the region of 3400 cm À1 was progressively increased, which could be possibly due to the increase in the content of the hydroxyl groups generated from the NaHCO 3 and also to the chemical reaction (hydrogen bonding) taken place between the NaHCO 3 -treated hemp fibers and the blend matrix. 33 In other words, the broad transmittance band detected in the wavenumber of 3400 cm À1 could be possibly attributed to the formation of hydrogen bonding between the chemically modified fibers and the DCBA/BA-a resin matrix.…”
Section: Ftir Spectra Of the Pure Blend And The Filled Compositesmentioning
This present study details an experimental investigation on understanding the effects of surface-modified waste hemp fibers on the overall properties of thermosetting resin blends composed of dicyanate ester of bisphenol-A and bisphenol-A-based benzoxazine resins. At first, the hemp fibers were subjected to sodium bicarbonate treatment, and then various experimental tests in terms of the Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis tests were, respectively, carried out to understand the influence of the as-used treatment on the structural, morphological, and thermal properties of the hemp fibers. The obtained results from the surface characterization evidently demonstrated the positive sodium bicarbonate impacts on the properties of the hemp fibers. After that, various amounts of the treated fibers were incorporated within the dicyanate ester of bisphenol-A/bisphenol-A-based benzoxazine resin blends and the obtained composite materials were characterized for their structural, mechanical behavior and thermal properties. The obtained results clearly revealed that the prepared blend composites were identified to possess good bending and impact strength properties; however, a slight decline was observed in the thermal properties. The scanning electron microscopy and Fourier-transform infrared spectroscopy investigations demonstrated a good dispersion of the fibers within the blend matrix, and also an enhanced fiber–blend matrix interfacial adhesion, which were plausibly behind the improved mechanical properties of the prepared blend composites.
“…However, due to the increase in environmental awareness and economic problems, the scientific community has focused on the employment of bio‐fillers, such as natural fibers. A variety of bio‐based materials were introduced as benzoxazine resin fillers such as basalt fibers, ramie fabric, chitosan, hemp fibers and sisal in order to further enhance its properties and reduce its various shortcomings …”
The exploration of curing process of benzoxazine resins, which possess outstanding features, is crucial for practical and advanced applications. In this study, bisphenol A-aniline based benzoxazine (BA-a) composites reinforced with alkali treated alfa fibers (TAF) were prepared. The influence of different loadings of the TAF on the curing kinetics of BA-a was investigated using non-isothermal differential scanning calorimetry (DSC) at different heating rates. Isoconversional integral methods or model free kinetics, namely, the iterative Kissinger-Akahira-Sunose (it-KAS), iterative Flynn-Wall-Ozawa (it-FWO), Sbirrazzuoli methodology (VYA/CE) and Trache-Abdelaziz-Siwa-ni (TAS) methods have been applied to the experimental data in order to evaluate the curing kinetic parameters. The study revealed that the presence of TAF improved the crosslinking reaction of benzoxazine and reduced the activation energy. The pre-exponential factor exhibited the same trend as the activation energy. The reaction model, examined for all composites, showed that all systems were accurately presented by an autocatalytic reaction model. The Avrami-Erofeev model was the most appropriate for describing the cure kinetics and revealed a good agreement with experimental data.
Polybenzoxazines, also known as Benzoxazine (Bz) is one kind of highperformance thermoset polymers. It manifests several advantages when used for thermal protection applications, such as thermal and dimensional stabilities, low rate of moisture absorption and near zero volatility in curing process. However, benzoxazine shows its drawbacks in terms of curing temperature, char yield at elevated temperature, and resin toughness. Thus, modification of Bz matrix would be essential in order to improve these unfavorable properties. In this study, a facile synthesis of phenylboronic acid-modified (PBA) benzoxazine (PBz) and glass fibers (GF) composites with varied PBA ratios were prepared. Briefly, GF fabrics were impregnated with each of Bz or PBz/acetone solution and baked to form B-staged prepregs. Then, the prepregs were stacked, molded and cured in a hot-pressing machine to form composites. The present study shows the 10 wt% PBA modified-Bz/GF composite is the optimal formulation as it exhibits minimal water uptake, enhanced char yield, decent thermomechanical stability in terms of glass transition temperature, exceptional interlaminar shear strength (ILSS) and highest flexural strength. Moreover, the PBz 10/GF composite subject to thermooxidative aging still maintains good levels of shear and flexural properties for potential service as thermal protection layer.
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