Phenol-formaldehyde Matrix Research Articles

Development of a high‐pressure infiltration process for phenol–formaldehyde matrix composites

AbstractPhenol–formaldehyde (phenolic) thermosets are known for excellent heat and chemical resistance, high flame retardance, and good mechanical performance. However, phenolics are also known for their high brittleness, and tendency to form voids, due to a condensation reaction forming water during curing. These voids can decrease the mechanical performance of the resultant phenolic composite and introduce undesirable performance characteristics. This work aims to develop a technique that uses high‐pressure infiltration to obtain dense phenolic matrix composites, with commercially available resin and fiber reinforcement. The high‐pressure system developed in this work is compared to a conventional low‐pressure resin infusion technique, and the porosity after each infusion is analyzed. A model of the low‐ and high‐pressure systems was developed, and the predicted time of infiltration was compared to the experimental results. The high‐pressure system had 97% less open porosity after infusion than the low‐pressure technique, suggesting that it can produce a higher‐quality and better‐performing phenolic composite than conventional techniques. Also, the mechanical test performed indicates improved performance for the high‐pressure injection with a 30.73% increase in ultimate tensile strength in comparison to low pressure, indicating better mechanical performance. © 2024 Society of Industrial Chemistry.

Recent study of PF/ZnO nanocomposites: Synthesis, characterization and optical properties

One of the earliest manufactured and most frequently used resins is phenol formaldehyde (PF) resin. Even with lesser loadings, their characteristics can be enhanced by the addition of nano-ZnO. The novel PF/ZnO Nanocomposites synthesis by ultrasonic process. The optical properties of materials modified with wide-band gap semiconductor described via UV–vis spectroscopy. Diffuse reflectance spectroscopy (DRS) one of the possible tool to measure the reflected light from powders and rough surfaces clearly. Spectra obtained by DRS treated with Kubelka-Munk function in order to describe the energy band gap accurately for modified and pure para hydroxy benzoic acid polymer. The band gap of para hydroxy benzoic acid is about 4.5 eV and in modified samples range from 3.4 to 3.3 eV; the lowest band gap value corresponds to the higher ZnO concentration (0.005gm). The surface morphology characterize by SEM and AFM m where obtain the effected nanostructure as increase on the surface morphology and the roughness which is increase according the aggregation occur. EDX mapping appearance increase the distribution and present of zinc nanostructured in modified polymer. It was discovered that this was because of the ZnO NPs' good dispersion in the polymer matrix and their robust interfacial interaction with the PF matrix.

Detailed investigation of effective trace Cr(VI) removal mechanism by anion exchange resin with phenol–formaldehyde matrix

Prolonged exposure to trace Cr(VI) concentrations in potable water can cause serious health problems in living beings. A weak base anion exchange resin, Duolite A7, showed a large capacity for trace Cr(VI) removal from a background of competing anions present at much higher concentrations, while conventional ion exchangers and adsorbents become ineffective due to lack of selectivity under similar conditions. The objective of this study was to find out the mechanism behind such significant capacity shown by the resin. Fixed-bed column studies showed that the resin was fully exhausted below 4,000 bed volumes (BVs) for pH 7, whereas no breakthrough was observed for 25,000 and 131,000 BVs at pH 5 and 3, respectively. Extensive characterization studies revealed that redox reactions were also occurring inside the resin in addition to ion exchange, where Cr(VI) oxidized the amine functional groups and phenol–formaldehyde matrix while itself getting reduced to Cr(III). Cr(III) formed was either precipitated inside the resin as Cr(OH)3 or bound with the oxidation products such as carboxylic acid groups. Analysis of treated water showed that formaldehyde, a carcinogen, was formed due to oxidative attack of Cr(VI) on the resin and was released in the effluent at trace concentrations. A detailed understanding of the mechanism would motivate the development of such redox-active sorbents for selective trace Cr(VI) removal from contaminated drinking water.

Waste coconut leaf sheath as reinforcement composite material withphenol‐formaldehydematrix

AbstractThis article describes the development and characterization of mercerized and untreated naturally woven waste coconut leaf sheath (CLS) fiber‐reinforced phenol‐formaldehyde (PF) composites. The composites of CLS fiber with 60% and 40% PF were manufactured hand lay technique followed by compression molding method. The investigation of composites was performed by applying tensile, bending, impact test, and measurements of water absorption rate and biodegradability characteristics. The CLS was mercerized using 5% of NaOH. The results confirm the superiority in mechanical properties of treated CLS fiber composites in respect to the untreated ones. The better properties are driven by lower hydrophilic hydroxyl groups and reduced impurities detected on the CLS fibers, which in turn reveals stronger adhesion and superior compatibility between CLS fiber and PF matrix. The rate of water absorption was evaluated within four different types of water conditions such as normal water, bore, distilled, and sea water, respectively. A degradation test was carried to determine biodegradability properties of composites. The superior results of treated CLS fiber composites validate this composite as a good candidate material for domestic and structural applications.

Influence of the particle size on the physical, mechanical and tribological properties of composites for brake pads

Tribotechnical indicators of environmentally friendly frictional composite materials with phenol-formaldehyde matrix are studied. Friction tests were carried out on a MMW-1 vertical tribometer according to the pin-on-disk scheme. Keywords: brake pads, composites, friction and wear, plasticizers, degradation, porosity. fikratyusub@gmail.com

Directed change of the functional properties of composite phenol-formaldehyde cationites

It was found that the modification of the cation-exchange phenol-formaldehyde matrix with a phenolic resin and addition of thermo- and microwave-treated basalt fiber filler at the stage of its synthesis provide a synergistic effect on the basic functional characteristics of the synthesized composite cationite.

Effects of cellulose nanofibrils on the cure kinetics of the phenol formaldehyde resin

Phenol formaldehyde (PF) resin were treated with cellulose nanofibrils (CNF), and its effects on the cure kinetics of PF resin were evaluated. The curing of PF resin was a polycondensation exothermic reaction forming insoluble polymer. The Differential scanning calorimetry (DSC) analysis showed 3% CNF addition had prolonged the curing process of PF resin, and the Kissinger equation and Crane equation were introduced to show that the curing activate energy and reaction order of 3%-CNF-added-PF resin sample were obviously lower than control ones. The scanning probe microscopy (SPM) results exhibited that CNF particles were well-dispersed in the PF matrix. The non-isothermal kinetic study indicated that CNF had played a major role during late stage of non-isothermal polymerization, increasing the crosslinking points in the PF resin and reducing the energy needed for PF resin curing. Thus, the addition of CNF had a positive effect on the curing of PF and made the curing more perfect.

Facile production of HNTs\PDA\PF nanocomposites by unique and environment-friendly method for the removal of phenolic pollutants in water as an environmental adsorbent

Abstract A new kind of hybrid nanocomposites (NC)s consisted of phenol-formaldehyde (PF), polydopamine (PDA) and modified halloysite nanotubes (HNT)s had been prepared by sonochemical synthesis. The surface modifications of HNTs were achieved by mussel inspired sonochemistry using dopamine (DA) as an active intermediate. In this process bio-safe DA could self-polymerized to adhere to the surface of HNTs and formed an active PDA species. The PF/PDA/HNT NCs had been fabricated by the in-situ polymerization of phenol, formaldehyde in alkaline condition in the presence of PDA modified HNTs through polycondensation reaction. Characterizations with FT-IR, powder X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) confirmed the synthesis of NCs with well dispersion properties. In continuation of the research the possiblity of application of prepared nanomaterials for removal of phenolic compounds were inspected. Obtained results showed that the presence of nanotubular filler, existance of different polar functional units in PDA structures, H-bonding and hydrophobic interactions of PF matrix with phenols are the key factors for improving the adsorption capacity for phenol by PF/PDA/HNTs NCs.

Bio‐inspired low dielectric phenol formaldehyde laminates for electrical insulation applications

AbstractIn this research work, the effect of individual and hybridized reinforcement of sisal fibrils with randomly distributed short sisal fibers has been investigated. The sisal fibrils (SP) and sisal fibers (SF) were reinforced with phenol formaldehyde matrix using hot stage compression molding technique. Composite laminates were prepared keeping the total wt% of the fibrils/fibers to be 40. The mechanical strength of SP reinforced phenol formaldehyde laminates was found to be superior as compared to sisal fiber and sisal fibril/fiber hybrid reinforced laminates. The 40 wt% sisal fibril reinforced composite laminates (SP40PF60) showed 73% and 25% increase in tensile strength, 78% and 23% increase in flexural strength, and 174% and 44% increase in impact strength as compared to 40 wt% sisal fiber reinforced laminates (SF40PF60) and 40 wt% hybrid reinforced (having equal proportion of fibrils and fibers) laminates (SF20SP20PF60). The dielectric properties of SP40PF60 increased by 14% and 9% as compared to SF40PF60 and SF20SP20PF60 laminates. Thermo‐gravimetric analysis analysis also showed higher thermal stability for sisal fibril phenol formaldehyde laminates than pure fiber and fibril/fiber hybrid laminates. Scanning electron microscopy was carried out to understand the nature of fibril/fiber/matrix interface. These laminates have been specially designed for press boards used in transformer assembly as environment friendly high mechanical strength and electrical insulating material. Additionally, these laminates can be useful for various fields such as electrical and aerospace industry.

Effect of Structural Heterogeneity of Polikon Mosaic Materials on Their Properties

A unique method for producing Polikon cation–anion exchange mosaic materials has been proposed. The materials were prepared by the polycondensation filling of polymer composites and via synthesis and curing of a weakly basic anion exchanger and a strongly acidic sulfonated cation exchanger on the surface and in the structure of a fibrous novolac phenol–formaldehyde matrix. Molecular models that characterize the chemical composition of the developed composites are given. The effect of the composition that facilitates the formation of a material with stable performance characteristics has been studied. The cause-and-effect relationships of the structural, physicochemical, and operational properties of the heterogeneous cation–anion-exchange mosaic materials Polikon under thermomechanical action at the stage of polymer matrix curing were investigated. Empirical equations that refine these relationships were obtained. The morphology and internal structure of the test heterogeneous membranes were characterized by scanning electron microscopy and energy-dispersive elemental analysis. The viscoelastic properties of the samples were studied by dynamic thermomechanical analysis.

Effect of Nanofillers on Abrasion Resistance of Carbon Fiber Reinforced Phenolic Friction Composites

The present study focuses on the development of polymeric friction composites with short carbon fiber, micron and nano-sized fillers, additives with varying weight% in phenol formaldehyde (PF) matrix using hot compression moulding process. The composites prepared with fillers viz. Molybdenum disulfide or Molykote (MK) and multi walled carbon nanotubes (MWCNTs) in carbon fiber reinforced PF matrix is designated as Set-I composites. Inclusion of graphite and nano-clay in carbon fiber reinforced PF matrix is designated as Set-II composites. The prepared composites are tested in Dry sand rubber wheel abrasion wear test rig, following ASTM standards for evaluating the abrasive wear behaviour. From the routine experiments, it was observed that the presence of combined micro and nanofillers i.e. 11.5 wt% MK + 0.5 wt% MWCNTs of Set-I, has shown superior abrasion resistance among the study group. The test results of the Set-I and Set-II composites are analyzed using Taguchi experimental design followed by analysis of variance (ANOVA) to understand the contributions of wear control factors affecting the abrasive wear characteristics. Further, worn surface of selected samples is analyzed using scanning electron micrographs.

Effect of starch reduced graphene oxide on thermal and mechanical properties of phenol formaldehyde resin nanocomposites

Phenol formaldehyde (PF) resins are one of the oldest synthesized and very widely used resins. Their properties can be improved with the incorporation nano-fillers even with lower loadings. Graphene materials have attracted significant attention in recent years owing to its exceptional thermal, mechanical and electrical properties. Herein, we report a very simple and effective way to reduce graphene oxide (GO) by using highly abundant potato starch instead of conventionally used toxic and hazardous reducing agents like hydrazine. The reduced GO (RGO) is then effectively incorporated into PF resin by optimizing various processing parameters. The reinforcing effect of RGO sheets on the PF matrix was investigated by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The effect of RGO on thermal properties of the polymer nanocomposites was studied using Thermogravimetric Analysis (TGA). The mechanical properties of PF/RGO composites were studied by tensile and Izod impact tests. The fracture mechanism of the composites was investigated by Scanning Electron Microscopy. Theoretical prediction of the mechanical properties of the nanocomposites using Halpin-Tsai models gave sufficient information regarding the orientation of graphene sheets in PF matrix.

Effect of short glass fiber and ferrosilicon content on mechanical properties of phenolic based friction composite material

This paper strives to eliminate the pros and cons of contemporary composition used in the preparation of composite brake blocks manufactured at Central Railway Workshop, Mysuru, India. The prime objective is to develop the composite material with optimum constituents for the application of brake blocks used in railway, emphasizing on the substitution of asbestos by short glass fiber (SGF) and ferrosilicon. Composites of phenol formaldehyde matrix with five different amounts of SGFs have been prepared. Significant differences between phenolic based composites with SGF and ferrosilicon reinforcements on hardness, compression and flexural properties were observed suggesting better compatibility of reinforcements with phenolic matrix. In the case of impact strength decreasing trends were observed as the content of ferrosilicon is varied. The effects of SGFs and ferrosilicon wt.% on mechanical properties are discussed in details.

Ultrasonic assisted synthesis of nanocomposite materials based on resole resin and surface modified nano CeO2: Chemical and morphological aspects

In this study, phenol-formaldehyde (PF)/CeO2 nanocomposites (NC)s were prepared by in-situ polymerization of phenol and formaldehyde in alkali solution in the presence of surface modified CeO2 nanoparticles (NP)s by sonochemical assisted synthesis. The morphology and structure of PF/CeO2 NCs were characterized by using fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal analyses methods. It was found that due to the good dispersion of surface modified NPs in polymer matrix and the strong interfacial interaction between the CeO2 NPs and PF matrix, the thermal stability and thermo-mechanical properties of the PF/CeO2 NCs were greatly enhanced. FE-SEM and AFM analyses showed the uniform distribution of CeO2 NPs in PF matrix. The XRD patterns of NCs show the presence of crystalline CeO2 NPs in amorphous matrix. The thermal analysis results reveal that, with increases in the content of CeO2 NPs in PF matrix, the thermally stability factors of samples were drastically enhanced.

Evaluation of Efficiency of Using the Modified Cationite to Purify the Monomer-Containing Wastewater

The analysis of the market showed that the demand to ionites in Russia rises annually and constitutes about 20 000 t/yr. Currently, the demand to polymer composites possessing the functional, particularly ion-exchange properties, is satisfied at the Russian market due to the import production by 80%, which causes the necessity to develop highly efficient domestic polymer ionites. A new highly efficient cationite based on the modified phenol formaldehyde matrix and thermally treated and microwave-treated basalt fiber is developed. This cationite can be recommended for using in water conditioning for systems of technical water supply as well as to purify the caprolactam-containing wastewater of PA-6 production when using the two-stage purification system.

Structure, Self-Similarity, and Fracture of Fiber-Reinforced Composites

We propose a theory for the relationship between structure and the self-similarity principle with initial damage and final fracture of composites. This relationship does not depend on the type of stress state, the dimensions of the composite, or the time scale. Based on the self-similarity principle, we have constructed the theoretical time-to-fracture distribution functions vs. the applied stress level, allowing us to estimate the lower limit corresponding to zero fracture probability. The distribution functions can be constructed without long-term testing. An estimate of the distribution of initial damage is obtained from the short-term strength distribution. As the critical parameter for the transition of the composite to final fracture, we take a critical measure of the stress tensor. At each instant of time, fracture is determined by a differential operator depending on the state of the system at that instant and the applied stress level. The theory is supported by experiments. The experiments were performed on model fiberglass-reinforced composites based on a phenol formaldehyde matrix under tension, compression, pure shear, and hydrostatic tension. The maximum testing time was ~ 20 000 hours. The theory is applicable to any systems with a partially ordered structure and satisfying the self-similarity principle (geophysical, social, economic, etc.).

Interactive Oxidation–Reduction Reaction for the in Situ Synthesis of Graphene–Phenol Formaldehyde Composites with Enhanced Properties

We report a facile in situ synthesis of reduced graphene oxide (RGO)-phenol formaldehyde (PF) composites with an interactive oxidation-reduction reaction. In this interactive chemical reaction, graphene oxide (GO) was reduced to RGO by phenol, and simultaneously phenol was oxidized to benzoquinone. The noncovalently adsorbed phenol on the RGO surface can not only serve as an effective reductant but also participate in the in situ polymerization and guide the formation of PF on the RGO surface. RGO-PF composites with different RGO contents were prepared successfully and further characterized with fluorescent spectroscopy, scanning electron microscopy, and transmission electron microscopy. The mechanical strength, electrical conductivity, thermal conductivity, and thermal resistance of the created RGO-PF were investigated. The results indicated that the dispersity of RGO in the PF matrix and the interfacial interaction between RGO and PF were improved greatly because of formation of the RGO-PF hybrid in the in situ synthesis. The homogeneous dispersion and in situ polymerization of RGO sheets help to enhance the thermal conductivity of RGO-PF composites from 0.1477 to 0.3769 W m(-1) K(-1) and endow the composites with a good electrical conductivity. In addition, the well-dispersed RGO-PF composites are much more effective in improving their mechanical property and heat resistance.

Characteristics of banana fibers and banana fiber reinforced phenol formaldehyde composites‐macroscale to nanoscale

Microfibers and nanofibers were prepared from macro banana fibers by a steam explosion process. The fiber surface of chemically modified and unmodified banana fibers was investigated by atomic force microscopy, the studies revealed a reduction in fiber diameter during steam explosion followed by acid treatments. Zeta potential measurements were carried out to measure the acidic property of the fiber surface; the surface acidity was found to be increased from macrofibers to nanofibers. The thermal behavior of macrofibers, microfibers, and nanofibers were compared. Substantial increase in thermal stability was observed from macroscale to nanoscale, which proved the high thermal stability of nanofibers to processing conditions of biocomposite preparation. The composition of the fibers before and after steam explosion and acid hydrolysis were also analyzed using FT‐IR. It was found that the isolation of cellulose nanofibres occurs in the final step of the processing stage. Further macrocomposites, microcomposites, and nanocomposites were prepared and mechanical properties such as tensile, flexural and impact properties were measured and compared. The composites with small amount of nanofibers induces a significant increase in tensile strength (142%), flexural strength (280%), and impact strength (133%) of the phenol formaldehyde (PF) matrix, this increase is due to the interconnected web like structure of the nanofibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1239‐1246, 2013

Preparation, Characterization, and Properties of In Situ Formed Graphene Oxide/Phenol Formaldehyde Nanocomposites

Graphene oxide (GO) has shown great potential to be used as fillers to develop polymer nanocomposites for important applications due to their special 2D geometrical structure as well as their outstanding mechanical, thermal, and electrical properties. In this work, GO was incorporated into phenol formaldehyde (PF) resin by in situ polymerization. The morphologies and structures of GO sheets were characterized by FTIR, XRD, and AFM methods. The structure and properties of the GO/PF nanocomposites were characterized using FTIR, XRD, DSC, and TGA methods. Effects of GO content, reactive conditions, and blending methods on the structure and properties of GO/PF nanocomposites were studied. It was found that due to the well dispersion of GO sheets in polymer matrix and the strong interfacial interaction between the GO sheets and PF matrix, the thermal stability and thermal mechanical properties of the GO/PF nanocomposites were greatly enhanced.

Polymeric matrices promising for immobilization of tritium radioactive wastes

The resistance of polymeric matrices to leaching of tritium water incorporated in oil microcapsules or in chemisorbent particles was studied. The phenol-formaldehyde matrix with tritium and cesium in oil microcapsules ensures highly reliable radionuclide immobilization: The half-decile leaching rate, g cm−2 day−1, is 9 × 10−5 for 3H and 2 × 10−5 for 137Cs. A borate chemisorbent in combination with a polyurethane matrix was suggested for immobilization of highly radioactive tritium water vapor.