•PANI-PA can be synthesized in phytic acid solution directly.•PANI-PA has a good thermostability.•2wt.% PANI-PA can obtain an a better inhibiting effect than other concentrations.•Epoxy coating ...blended with PANI-PA particles possesses a self-healing function.
Corrosion protection of epoxy coatings contained with phytic acid-doped polyaniline (PANI-PA) for Q235 carbon steel was studied in this work. Synthesized PANI-PA particles were characterized by XPS, TGA, and FTIR, respectively. The coating performance was investigated by OCP, EIS, and SVET, respectively. The experimental results show that the concentration of PANI-PA has a significant influence to the barrier effect of the epoxy coating. Epoxy coating loaded with 2wt.% PANI-PA has the best protection ability and self-healing function to a certain degree. The self-healing function of PANI-PA is attributed to the synergistic effect of the passivation of PANI and the chelation of the dedoped phytic acid ions with iron ions. Therefore, PANI-PA can be used as an effective anticorrosion pigment in future.
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Polyisocyanate and caprolactone were used to chemically functionalize nanocellulose (CNF). Composites of CNF, caprolactone-modified nanocellulose (CNF-CL) and polyisocyanate-modified nanocellulose ...(CNF-JQ)/MC nylon were fabricated by anionic ring-opening polymerization. The effects of the crystal structure, crystal morphology and crystallization process of MC nylon composites have been characterized by wide-angle X-ray diffraction (WAXD), polarized optical microscopy(POM) and differential scanning calorimetry (DSC). Isothermal crystallization kinetics were analyzed using the Avrami equation, and the crystallization rate, half-time, and Avrami exponent were calculated. The results show that the nucleation effects of CNF-JQ/MC nylon composites is increased with the CNF-JQ increase, and it is best compared with MC nylon, CNF/MC nylon and CNF-CL/MC nylon composites, so CNF-JQ can play the role of effective nucleating agent in MC nylon. We also discussed the non-isothermal crystallization of the composites. Analysis of the Jeziorny and Mo model demonstrates that the Zc values of CNF, CNF-CL, CNF-JQ/MC nylon composites increase, and the F(T) values decrease in order. This indicates that CNF-JQ can better promote the crystallization rate of non-isothermal crystallization of MC nylon. The results of this work demonstrate that CNF-JQ can be an effective nucleation agent and increase the crystallization rate of MC nylon compared with CNF-CL. The activation energy of the composites was studied using the kissing method, and the results showed that CNF-CL decreased the activation energy of MC nylon, and CNF and CNF-JQ increased the activation energy of MC nylon.
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The effects of the formaldehyde to phenol molar ratio (F/P) on the combustion behavior of phenolic foams were discussed. Phenolic foams have been prepared with different F/P of resole resin. FTIR, TG ...and SEM were used for assessment of the molecular structure, thermal stability, and cell structure of phenolic foam (PF) analysis, respectively. It was found that the higher the F/P, the more inflammables content in the PF that promoted the formation of the char layer, and the higher the LOI of PF. Although the closed cell proportion of PF decreases with the increase of F/P, the effect of the open and closed cell proportion on the LOI of PF was much lower than that of the content of inflammables when there was little difference in cell size. It is worth noting that the smoldering time and smoldering velocity of PF also increased with the increase of F/P. When F/P exceeds 2.3, a large number of open-cell structures appear in the PF, resulting in a phenomenon of smoldering to burnout. The relationship between smoldering velocity and F/P can be calculated by an Arrhenius type expression. Arrhenius-type expression calculation showed that when the F/P reached 2.3, the smoldering velocity increased sharply, reaching a maximum of 0.193 mm/s.
•The factors affecting the combustion behavior of phenolic foam (PF) were revealed.•The effect of closed cell proportion on LOI of PF is lower than that of the content of inflammables.•The higher the formaldehyde to phenol molar ratio (F/P), the greater the smoldering time and velocity.•The relationship between smoldering velocity and F/P can be calculated by an Arrhenius type expression.
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In this present study, 3-pentadecyl-phenol was selected as a modifier to prepare a foamable phenolic resin with excellent performance, which was successfully prepared by in situ modification. Fourier ...transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (¹H NMR,
C NMR) were used to test and characterize the molecular structure of the modified resin. The results showed that 3-pentadecyl-phenol successfully modified the molecular structure of phenolic resin with a reduction in the resin gel time. The effect of changing the added amount of 3-pentadecyl-phenol on the mechanical properties, microstructure, and flame retardancy of the modified foam was investigated. The results showed that when the amount of added 3-pentadecyl-phenol was 15% of the total amount of phenol, this resulted in the best toughness of the modified foam, which could be increased to 300% compared to the bending deflection of the unmodified phenolic foam. The cell structure showed that the modified phenolic foam formed a more regular and dense network structure and the closed cell ratio was high. Furthermore, the compressive strength, bending strength, and limited oxygen index were improved, while the water absorption rate was lowered. However, the foam density could be kept below 40 mg/cm³, which does not affect the load.
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In the present study, acetoacetic ester-terminated polyether was selected as a modifier to prepare a new type of polyether phenolic resin, which was successfully prepared by pre-synthesis ...modification. It is used to prepare interpenetrating cross-linked network structure modified phenolic foam with excellent mechanical properties. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (¹H NMR,
C NMR) were used to characterize the molecular structure of the polyether phenolic resin. The results showed that the acetoacetic ester-terminated polyether successfully modified the phenolic resin and introduced a polyether skeleton into the resin structure. The effect of changing the added amount of acetoacetic ester-terminated polyether from 10% to 20% of the phenol content on the mechanical properties and microstructure of the modified phenolic foam was investigated. The results showed that when the amount of acetoacetic ester-terminated polyether was 16% the amount of phenol, this resulted in the best toughness of the modified foam, which had a bending deflection that could be increased to more than three times that of the base phenolic foam. The modified phenolic foam cell diameter was reduced by 36.3%, and the distribution was more uniform, which formed a denser network structure than that of the base phenolic foam. The bending strength was increased by 0.85 MPa, and the pulverization rate was as low as 1.3%.
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In this experiment, terephthalyl alcohol was used as a modifier to modify phenol under both acidic and alkaline conditions to obtain modified phenols with different molecular structures. ...Subsequently, the modified phenols reacted with paraformaldehyde in an alkaline environment. After foaming and curing, a modified phenolic foam with high heat aging resistance was obtained. The molecular structure was characterized via Fourier transform infrared spectrometry (FT-IR) and nuclear magnetic resonance spectroscopy (
C NMR). The results showed that two different structures of phenolic resin can be successfully prepared under different conditions of acid and alkali. The modified phenolic foam was tested by thermogravimetric analysis. In addition, the modified phenolic foam was tested for mass change rate, dimensional change rate, powdering rate, water absorption rate, and compressive strength before and after aging. The results show that the modified phenolic foam has excellent performance. After heat aging for 24 h, the mass loss rate of the modified phenolic foam obtained by acid catalysis was as low as 4.5%, the pulverization rate was only increased by 3.2%, and the water absorption of the modified phenolic foam increased by 0.77%, which is one-third that of the phenolic foam. Compared with the phenolic foam, the modified phenolic foam shows good heat aging resistance.
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The copolyester poly(butylene glycol adipate-co-terephthalate/diphenylsilanediol adipate-co-terephthalate) (PBDAT) was synthesized by the melt polycondensation method using terephthalic acid, adipic ...acid, 1,4-butanediol, and diphenylsilylene glycol as the raw materials. The molecular chain structure, thermal properties, thermal stability, mechanical properties, and degradation behaviors of the copolyesters were investigated. The results showed that the prepared PBDAT copolyesters exhibited good thermal stability and mechanical properties. With the increase in diphenylsilanediol (DPSD) content, the thermal stability of PBDAT and the melting temperature both increased. The tensile strength and elastic modulus of PBDAT also exhibited an increasing tend. When the DPSD content was 12.5% (PBDAT-12.5), the tensile strength, the elastic modulus, and elongation at break were 30.56 MPa, 238 MPa, and 219%, respectively. With the increase in diphenylsilanediol content, the hydrophilicity of PBDAT decreased, but PBDAT still shows good degradability and the thermal degradation T5% temperature was 355 °C. The thermal degradation of PBDAT was also improved.
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Ceramifiable phenolic foam (GC-PF) with a low ceramization temperature has been prepared by incorporation of low melting point glass frits (LMG) containing B
O
and Na
O as main components into a ...phenolic resin matrix. Fourier transform infrared spectrometry, X-ray diffractometry, and scanning electron microscopy were used for assessment of the structure, phase composition, and morphology of GC-PF before and after combustion analysis, respectively. A glassy ceramic protective layer is formed when GC-PF is exposed to flame or a high temperature environment. The presence of LMG not only reduces the level of defects in the phenolic foam cell wall (gas escape pore), but also promotes the generation of a glassy ceramic protective layer that could inhibit heat feedback from the combustion zone and reduce the rate of formation of volatile fuel fragments. Thermogravimetric analysis and differential scanning calorimetry were used to establish that GC-PF exhibits excellent thermal stability. Limiting oxygen index (LOI) determination suggests that GC-PF displays good flame retardancy. The LOI of GC-PF was as high as 45.6%, and the char residue at 900 °C was six times greater than that for ordinary phenolic foam (O-PF). The area of the raw material matrix of GC-PF after combustion for 60 s was about 1.7 times larger than that for O-PF. A possible mode of formation of glassy ceramics has been proposed.
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•The corrosion rate of mild steel is reduced upon the addition of tannic acid.•The inhibition efficiency of tannic acid is greatly enhanced in presence of I−.•The thickness of the inhibitors layer ...increases with increasing immersion time.•The mixture of tannic acid and I− can provide a long term protection for mild steel.
The synergistic effect of tannic acid and I− in H2SO4 solution has been studied through electrochemical impedance spectroscopy, potentiodynamic polarization curves, immersion tests, weight loss tests, and scanning electron microscopy in present work. The results show that tannic acid and iodide ions have an obvious synergistic inhibiting effect in H2SO4 solution. SEM images indicate that the absorbed mixed inhibitors layer composed of tannic acid and I− can provide a long term protection for mild steel in 0.1M H2SO4 solution. The mixed inhibitor composed of tannic acid and iodide ions is an effective inhibitor for mild in acid solution.
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Graphene oxide (GO) treated with dicyclohexylmethane-4,4′- diisocyanate (HMDI) was first synthesized and termed FGO. Fourier transform infrared spectroscopy (FTIR), energy dispersive ...spectrometer(EDS), and X-ray diffractometry (XRD) were carried out to characterize the FGO structure. The results showed that the dispersibility of FGO in solvent was improved. Nuclear magnetic resonance(NMR) crosslinking density tester measuring crosslink density, room-temperature vulcanized silicone rubber was prepared with hydroxy-terminated polydimethylsiloxane (HPDMS) treated with FGO as a co-crosslinking agent, resulting in FGO/HPDMS. The FGO/HPDMS composites were proven to be successfully prepared by FTIR and XRD. The effects of the addition of different amounts of FGO on the crosslinking density, thermal conductivity, and mechanical properties before and after hot air aging of the FGO/HPDMS composites were investigated. As the amount of FGO was increased, the thermal conductivity and mechanical properties of the FGO/HPDMS composites increased. At 20% FGO addition, the corresponding thermal conductivity of the FGO/HPDMS composites was 1.24 W/mK.
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•HMDI-modified graphene oxide was used as a co-crosslinking agent to modify silicone rubber.•Measurement of crosslinking density by nuclear magnetic resonance method.•The thermal conductivity of the silicone rubber was 1.24 W/mK.
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