Traditional Phenolic Resin Research Articles

Improved ablation resistance of silicone/phenolic hybrid resin coatings with Zr-Si-O glass as anti-ablation layer

With the development of the new generation space vehicles, traditional phenolic resin (PR)-based coatings are no longer able to meet the increasingly harsh thermal environment. There is an urgent need to develop higher performance PR to ensure the flight safety of aircraft. Therefore, in this work, a novel hyperbranched polysiloxane containing Si-O-Zr bond was synthesized and then introduced into PR to develop homogeneous silicone/phenolic hybrid resin coatings. The TG results indicate that the introduction of Si-O-Zr bonds significantly improves the heat resistance of silicone. During ablation, the hyperbranched polysiloxane will undergo a ceramization to produce SiO2 and ZrO2 particles, both of which will subsequently generate a highly viscous Zr-Si-O glassy phase as anti-ablation layer. With the fluidity and self-healing properties, it can fill the gaps of the carbon layer and cover the surface of the carbon layer, giving the hybrid resin excellent ablative resistance. The linear ablation rate of the hybrid resin can be as low as 0.003 mm/s, which is an 80 % decrease compared to pure PR. The synthesized hybrid resin is expected to act as superior thermal protection coatings for the next generation of spaceflight.

Green preparation of versatile silver-based nanocomposites using whole biomass-based Tannin-Furfural as raw materials

Phenolic resin (PR) nanomaterials, which serve as excellent carriers for precious metals, are typically synthesized via the cross-linked reaction of phenol and formaldehyde, and both are toxic. Therefore, replacing them with whole biomass-based materials is an attractive alternative; however, it has proven to be a significant challenge. In this study, we successfully prepared versatile Ag-based resin nanocomposites (referred to as TFR@Ag) by utilizing whole biomass-based tannin and furfural as raw feedstock. The resulting TFR nanospheres exhibited high stability and uniformity, with tunable sizes ranging from 280 to 1430 nm by adjusting the amount of ammonia used in the synthesis process. Importantly, compared to traditional PR nanospheres, the novel and environmentally friendly TFR nanospheres possess abundant phenolic-OH groups that significantly enhance their adsorption, reduction and chelation capacity for Ag+. The highest loading amount of silver nanoparticles (Ag NPs) achieved was up to 60.3 wt% with a size of only 10.6 nm. The as-obtained TFR@Ag nanocomposites demonstrated excellent catalytic activity in treating typical hazardous dye-containing wastewater. As catalyst, the 0.4 mg TFR@Ag were capable of achieving full reduction of 2 mL 40 mg·mL−1 methylene blue (MB) and methyl orange (MO) in just one minute, exhibiting reaction rate constants of 1.71 min−1 and 2.40 min−1, respectively. Moreover, as antibacterial agents, the TFR@Ag nanocomposite effectively inhibited the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with a bacterial inhibition rate close to 100 %. This work presents a new strategy for green synthesis of multi-functional Ag-based nanocomposites that hold great potential in various fields such as catalysis, nanomaterials science and biomedicine.

Revitalizing Traditional Phenolic Resin toward a Versatile Platform for Advanced Materials

Revitalizing Traditional Phenolic Resin toward a Versatile Platform for Advanced Materials

Mechanical properties, thermal stability, and mechanism of main‐chain polybenzoxazine composites fabricated based on multi‐scale effects and surface functionalization of graphene oxide nanosheets

AbstractPolybenzoxazine (PBZ) has been recognized as a potential substitute for traditional phenolic resin. However, poor flexibility and low heat resistance limited obviously the application of PBZ. Herein, graphene oxide (GO) nanosheet and its amino‐rich derivatives (fGO‐g‐SiO2) with multi‐scale surfaces were designed, synthesized and incorporated into main‐chain PBZ through in‐situ polymerization to fabricate PBZ composites. The morphology, mechanical properties, and thermal stability of the composites were systematically investigated using x‐ray diffraction (XRD), contact angle tests, field emission scanning electron microscopy (FESEM), tensile and impact tests, and thermogravimetric analysis (TGA). FTIR and XRD analyses confirmed the multi‐scale surfaces of GO derivatives and ordered structures, respectively. The size of the in‐situ grown SiO2and the thickness of GO coated on PBZ were estimated as 6.5 and 19.07 nm, respectively. The contact angle test revealed thatfGO‐g‐SiO2and BZ had the closest solid surface energy of 32.002 and 43.519 mN/m, respectively, among the components of the composites. The impact and tensile evaluation revealed the highest impact, tensile strength and Young's modulus of 16.75 kJ/m2, 107.24 MPa and 3.17 GPa, respectively for 1.2%fGO‐g‐SiO2/PBZ composite. The modified Halpin‐Tsai equation was also utilized to develop a predictive function for the tensile strength. FESEM offGO‐g‐SiO2/PBZ composites indicated that the multi‐scale effect and amination effectively improved the restriction of GO derivatives on crack propagation in PBZ composites and played a more significant role in crack deflection and bridging. In addition, the highest thermal decomposition activation energy of 166.94 kJ/mol was achieved for 1.2%fGO‐g‐SiO2/PBZ composite.HighlightsGraphene oxide (GO) nanosheets were incorporated into main‐chain polybenzoxazine (PBZ) to improve its mechanical properties and heat resistance.GO with multi‐scale structure and amino‐rich interface were designed, synthesized to improve the interface interactions with PBZ matrix.The GO with multi‐scale structure and amino‐rich interface showed excellent similarity in the term of solid surface energy with benzoxazine oligomers.The morphology, mechanical and thermal stability of resulting PBZ composites was systematically investigated by using experimental and mathematical model to elucidate the relationships between the structure and properties.The composites exhibited excellent mechanical and thermal properties, and it is expected to be used as advanced engineering material in demanding environments.

Thiol‐Aldehyde Polycondensation for Bio‐based Adaptable and Degradable Phenolic Polymers

AbstractDesigning sustainable materials with tunable mechanical properties, intrinsic degradability, and recyclability from renewable biomass through a mild process has become vital in polymer science. Traditional phenolic resins are generally considered to be not degradable or recyclable. Here we report the design and synthesis of linear and network structured phenolic polymers using facile polycondensation between natural aldehyde‐bearing phenolic compounds and polymercaptans. Linear phenolic products are amorphous with Tg between −9 °C and 12 °C. Cross‐linked networks from vanillin and its di‐aldehyde derivative exhibited excellent mechanical strength between 6–64 MPa. The connecting dithioacetals are associatively adaptable strong bonds and susceptible to degradation in oxidative conditions to regenerate vanillin. These results highlight the potential of biobased sustainable phenolic polymers with recyclability and selective degradation, as a complement to the traditional phenol‐formaldehyde resins.

Thiol-Aldehyde Polycondensation for Bio-based Adaptable and Degradable Phenolic Polymers.

Designing sustainable materials with tunable mechanical properties, intrinsic degradability, and recyclability from renewable biomass through a mild process has become vital in polymer science. Traditional phenolic resins are generally considered to be not degradable or recyclable. Here we report the design and synthesis of linear and network structured phenolic polymers using facile polycondensation between natural aldehyde-bearing phenolic compounds and polymercaptans. Linear phenolic products are amorphous with Tg between -9 °C and 12 °C. Cross-linked networks from vanillin and its di-aldehyde derivative exhibited excellent mechanical strength between 6-64 MPa. The connecting dithioacetals are associatively adaptable strong bonds and susceptible to degradation in oxidative conditions to regenerate vanillin. These results highlight the potential of biobased sustainable phenolic polymers with recyclability and selective degradation, as a complement to the traditional phenol-formaldehyde resins.

INCREASING OF THE CORROSION RESISTANCE OF FIBERGLASS PLASTIC REINFORCEMENT THROUGH MODIFICATION OF THE POLYMER BINDER

The issue of increasing the corrosion resistance of composite reinforcement, based on glass fiber and epoxy anhydride binder, is considered. The proposed samples of composite reinforcement were manufactured by needle extrusion technology. Glass fibers were evenly distributed in the channels and impregnated with a polymer binder based on epoxy resin. The amount of phenolic modifier in the polymer binder, according to the technological mode of obtaining composite reinforcement, was brought up to 5%. With a further increase in the content of the modifier, the degree of conversion of epoxy groups was no more than 70%, which sharply reduced the operational characteristics of the material. The overall ratio of polymer binder and glass reinforcement in the composite was ~ 60÷40. It was established that at low concentrations of the polymer modifier (up to 5 wt. parts), the processes of ordering and chemical grafting lead to compaction of the molecular grouping in the system, which in our case is characteristic of phenolic resins of the novolach and resol types. At the same time, under the conditions of the production technology, internal stresses in materials of this type increase sharply, which leads to the formation of surface defects (microcracks). At the tip of a crack or defect, sodium ions or other cations under the action of water undergo hydrolysis to form metal hydroxide, which, in turn, causes hydrolysis of siloxane bonds, thus weakening the mesh structure of silicon dioxide. The experimental activation energy was identified with the activation energy of sodium ion diffusion in the glass mass. But the plastic deformation of the glass in the region before the crack is very small, and instead of a uniform distribution of stress, the material cracks along the weakened centers The obtained data indicate that the action of the alkaline environment causes an increased loss of mass of the composite, both for the unmodified and for those modified with traditional phenolic resins. In turn, this ensures a high degree of penetration of alkalis into the volume of the material, access to reinforced fibers with their subsequent damage. To increase the corrosion resistance of composite reinforcement based on an epoxy anhydride binder, it is advisable to use a reactive sulfur-containing phenolic modifier. Its action is based on the ability to maintain the permissible monolithicity of fiberglass in the alkaline environment of concrete, the modulus of elasticity and necessary strength. Keywords: composite polymer reinforcement, fiberglass, alkaline environment, phenolic modifier.

Silica sol nanoparticles hybridized allyl phenolic resins for improving mechanical and thermal performance

In order to improve the mechanical and thermal performance of traditional phenolic resins, nonpolar silica sol nanoparticles with different particle sizes were introduced into allyl phenolic resins with the presence of solvents. A series of allyl phenolic resins with various etherification degrees were designed and synthesized to investigate phase separation phenomenon between sol nanoparticles and allyl phenolic resins. Cured organic-inorganic hybrid samples for performance evaluation were then prepared under the pressure of 1 MPa and pressureless conditions at 250 °C, respectively. SEM observation results reveal that parameters of particle size, etherification degree, and pressure have remarkable influence on phase separation behaviors. Mechanical test and thermal stability evaluation using TGA, muffle furnace and butane torch burning tests prove that both mechanical performance and thermal stability of allyl phenolic resin could be extensively enhanced through the introduction of silica sol nanoparticles. This study provides fundamental understandings about functions and phase separation behaviors of silica sol nanoparticles in the phenolic resin matrix. Organic-inorganic hybrid materials were prepared from nonpolar silica sol nanoparticles with varied particle sizes and allyl phenolic resins with a series of etherification degrees. The hybrid materials exhibit enhanced mechanical strength and remarkable anti-ablative performance by forming a dense protective layer on the burned surface. • Nonpolar silica sol nanoparticles can be homogeneously distributed in the matrix of PRMs in the nanometer level. • Phase separations in hybrid samples can affect the thermal properties of PRMs. • The content and size of silica sol nanoparticles in the matrix evidently influence the mechanical performance of PRMs. • In the butane torch ablation tests, silica sol nanoparticles can remarkably enhance the anti-ablative performance.

Study on improving the high-temperature oxidation resistance of pyrolytic carbons of phenolic resin binder by in-situ formation of carbon nanotubes

In order to improve the high-temperature oxidation resistance of the traditional phenolic resin binder, nickel nitrate was added into the phenolic resin as the catalyst precursor, while carbon nanotubes (CNTs) could be in-situ formed inside the pyrolytic carbons during the pyrolysis process. The influence of pyrolysis temperatures on the formation of CNTs in pyrolytic carbons was investigated. The results showed that CNTs with the diameter of 20–40 nm were formed in pyrolytic carbons, while the nickel nitrate and the gases released through the pyrolysis of phenolic resin were respectively served as the catalyst and the carbon sources. Meanwhile, the increased temperature could promote the formation of the CNTs, and further improve the graphitization degree and the high-temperature oxidation resistance of the pyrolytic carbons. The high-temperature oxidation resistance of corundum graphite composite materials could be effectively improved by using phenolic resin with nickel nitrate as the binder, which demonstrates it to be a promising binder for high-temperature application.

A novel environment-friendly polyester binder to reduce the pollution of particulate matter produced by combustion of pyrotechnic

Traditional phenolic resin binder is prepared by chemical catalysis of toxic fossil raw materials with toxic wastewater produced in the process. The pyrotechnic with phenolic resin as binder cannot be fully burned, resulting in particulate matter pollution, which is harmful to human body and pollutes the environment. In this study, a new polyester pyrotechnic binder (Mn = 2834 g/mol, PDI = 1.22) was prepared by using bio-based monomers catalyzed by novozym 435. There is almost no waste and pollution in the whole preparation process. Pyrotechnic agents were prepared with the new polyester binder, and compared with the phenol resin binder. The results show that the pyrotechnic agent with polyester binder has good mechanical properties and high safety. It can reduce the heat release by 54.5%, accelerate the combustion rate by 31%, increase the gas production by 25%, reduce the combustion particulate matters by 52.8%. The clean preparation technology of polyester and the low particulate matter after combustion confirm that it is a new environment-friendly pyrotechnic binder which can replace phenolic resin.

Situ preparation of SiO2 on graphene-assisted anti-oxidation for resol phenolic resin

Easily oxidized group of traditional phenolic resin (PF) results in poor oxidation resistance at high temperature, which is unable to satisfy the requirements of advanced aerospace vehicles for high-performance application, especially ablation resistance. In order to improve the oxidation resistance of PF, a SiO2/RGO binary hybrid nanomaterial assisted anti-oxidation for PF was designed. Here, we reported a simple sol-gel process and high temperature reduction for synthesis of dispersed SiO2 nanoparticles on graphene (G-S). The designed structure of G-S was confirmed by FTIR, XRD, SEM and TEM. Introduction of G-S into PF (P-G-S) was beneficial to enhancement of oxidation resistance in whole temperature range (0–1000 °C). P-G-S-3 (3 wt.% of G-S) exhibits both lower thermal oxidative decomposition rate and higher termination temperature of thermal oxidative decomposition (increase from about 750 °C up to 900 °C) than those of neat PF in air. In addition, P-G-S-3 decomposed by thermal oxidation in air (at 557 °C, weight loss> 30 wt.%) later than neat PF (at 519 °C, weight loss> 20 wt.%). What's more, compared to the collapse of skeleton structure and few residual fragments of neat PF, P-G-S-3 showed greater oxidation resistance which resulted in the retention of a large number of aromatic C-C, methylene and different kinds of ether bond at temperature from 550 °C to 700 °C by FTIR and XPS. The section of P-G-S-3 expresses skin lamination that can act as a barrier to slow down the diffusion of oxygen into resin matrix. And SiO2 on the surface protected the matrix continually as indicated from the SEM analysis.

Furan resins as replacement of phenolic protective coatings: Structural, mechanical and functional characterization

Phenolic coatings are usually a convenient and economical way to protect metallic materials against wear and corrosion. Furan resins are analogous to phenolics, as they are obtained by replacing formaldehyde by furfural in their formulation. In this work, a furan resin based on furfural and phenol was synthesized and used as an aluminum coating. Thus, toxic emissions of formaldehyde were avoided, while a biobased derivative was used instead. The performance of the proposed resin was compared with the one of a traditional phenolic resin. Physicochemical characteristics including chemical structure, surface polarity and glass transition temperature were evaluated by means of Fourier transform infrared spectroscopy, contact angle measurements and dynamic–mechanical analysis, respectively. Nanomechanical and nanotribological properties were assessed by depth sensing indentation techniques. As well, the corrosion resistance of the furan coating was determined by potentiodynamic polarization tests. The obtained results validate the furan resin as a feasible alternative to phenolics to protect aluminum.

Furan resin as a replacement of phenolics: influence of the clay addition on its thermal degradation and fire behaviour

SummaryNanocomposites based on a furan resin and different types of clays were obtained. Their thermal and fire behaviours were compared with traditional phenolic resins, which are known by their excellent flame resistance. Three types of montmorillonite clays were in situ added to the thermosetting matrix. A cone calorimeter and a smoke chamber were used to evaluate the performance of the materials against fire and their smokes generation. Global parameters were calculated for comparison purposes. Fires derived from the furan resin combustion grow faster than the phenolic ones, but they are extinguished more rapidly. This effect is enhanced by the incorporation of inorganic nanofillers. The only addition of any clay causes shorter fires but slightly speeds up the degradation process. A homogeneous nanofiller dispersion was found to be crucial to achieve good fire behaviour. Nevertheless, for materials with similar dispersion, the crosslinking degree of the polymer matrix appears as a secondary factor that determines slighter differences in the performance. Nanocomposites with organomodified clays showed a quite similar fire performance, though the composite containing the clay (Southern Clay Products, Inc., Louisville, Ky, USA) Cloisite®30B showed the best performance taking into account both the fire risk and the smoke evolution and obscuration. Copyright © 2013 John Wiley & Sons, Ltd.

High Performance Polybenzoxazines as a Novel Type of Phenolic Resin

Polybenzoxazines that can be obtained by the thermally induced ring-opening polymerization of cyclic benzoxazine monomers are expected as a novel type of phenolic resins. Various benzoxazine monomers are easily synthesized from mono- or diamines, mono- or bisphenols, and formaldehyde. Polybenzoxazines have not only the advantageous properties of the traditional phenolic resins such as the high thermal properties, but also other properties that are not found in the traditional phenolic resins such as the molecular design flexibility, and excellent dimensional stability. The disadvantages of the typical polybenzoxazines are high temperature needed for the cure and brittleness of the cured materials. Further enhancement of thermal properties is also expected for the applications in harsh conditions. Herein, we report on our various approaches for performance enhancement of the polybenzoxazine, including the designs of novel monomers, high molecular weight polymeric precursors, polymer alloys, and hybrids with inorganics.

High Performance Polybenzoxazines as Novel Thermosets

Polybenzoxazine as a novel phenolic type thermoset has been developed to overcome the shortcomings associated with the use of the traditional phenolics. It can be prepared from cyclic benzoxazines via thermally induced ring-opening polymerization. Various benzoxazine monomers can be synthesized from mono-or diamines and mono-or bisphenols with formaldehyde. Polybenzoxazines have not only the advantageous properties of conventional phenolic resins such as high thermal properties, but also other interesting advantages that are not found in the traditional phenolic resins such as excellent dimensional stability. The disadvantages of the typical polybenzoxazines are the high temperature needed for complete cure and the brittleness of the cured materials. Further improvement of thermal properties is also expected for application in harsh conditions. Herein we report on various approaches for performance improvement of polybenzoxazine. These approaches include alloying with other high performance polymers, hybridization with inorganics, and designing of novel monomers as well as high molecular weight polymeric precursors. By these approaches, lowering of the cure temperature, improvement of toughness, and enhancement of thermal and mechanical properties were achieved.

Synthesis and characterization of novel dihydrobenzoxazine resins

AbstractThree dihydrobenzoxazines are synthesized from bisphenol A (BPA), 4,4′‐biphenol (BIP), and dicyclopentadiene phenol adduct (DCPD). Polydihydrobenzoxazine containing 4,4′‐biphenol (BIPDB) had the most rigid structure of the three and was found to possess the best mechanical and thermal properties. The glass transition temperature of BIPDB was 206°C, and that of BPA‐type polydihydrobenzoxazine (BPADB) and dicyclopentadiene type polydihydrobenzoxazine (DCPDDB) were 184 and 183°C, respectively. DCPDDB, with a rigid hydrophobic cycloaliphatic structure, was found to possess excellent properties such as low moisture absorption, low dielectric constant, low polarization. The resulted polymer from DCPDDB had a dielectric constant of 2.94U, which was better than that of polymers derived from BPA (3.31U), BIP (3.45U), and traditional phenolic resin (3.9–4.0U). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 342–347, 2006

Curing kinetics of a new benzoxazine-based phenolic resin by differential scanning calorimetry

The curing reactions of benzoxazine precursors based on bisphenol A and aniline are studied to determine the feasibility of processing them into final phenolic parts. Benzoxazine precursors are able to overcome most of the shortcomings of traditional phenolic resins, and retain the excellent heat resistance and fire and smoke properties of these resins. This new type of phenolic material cures via a ring-opening mechanism that does not produce any condensation or other reaction by-products. Phenol is not used as raw material, which reduces considerably the environmental and health risks. According to differential scanning calorimetry (d.s.c.), the curing of benzoxazine precursors is an autocatalysed reaction until vitrification is reached, and diffusion begins to control the curing process afterwards. Isothermal and non-isothermal d.s.c. tests are performed. Calculations of the activation energy and the overall reaction order are made by various procedures. The vitrification times and the kinetic rate constants are also calculated.