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69CHEMICAL SCIENCES
PROPERT i ES OF MOD i F i ED EPOXY RES i NS (Review)
Musayeva A. Yu.
PhD in Chemistry, Azerbaijan State University Oil and industry
Huseynova G.M.
II year in master of the Department of "Technology Organic Substances and High-Molecular Compounds ", Azerbaijan State University Oil and industry
Azerbaijan, Baku
ABSTRACT
Modifying epoxy resins changes the properties, improved physico-chemical, physico-mechanical and operational properties of epoxy resins.
Keywords: epoxy resins; latexes; modified; micro-nanocomposites; electrical properties; mechanical properties; thermal properties; high-voltage applications;; epoxy resins; numerical and analytical models; polymer-filler interface.
The first production of epoxy resins occurred simultaneously in Europe and in the United States in the late 1930s and early 940s. Credit is most often attributed to Pierre Castan of Switzerland and S.O. Greenlee of the United States who investigated the reaction of visphenol-A with epichlorohydrin. The families of epoxy resins that they commercialized were irst used as casting compounds and coatings. The same resins are now commodity materials hat provide the basis for most epoxy formula- ions.
Epoxy resins are a class of thermoset materials ised extensively in structural and specialty composite applications because they offer unique combination of properties that are unattainable whith other a thermoset resins.
Available in a wide variety of physical forms from low- viscosity liquid to high- melting solids, they are amenable a wide range of processing and applications.
Epoxy a resins are routinely used as adhesives coatings, encapsulates, casting materials, potting compounds, and binders. Some of their most interesting applications are found in the aerospace and recreational industries where resins and fibers are combined to produce complex composite structures.
Epoxy technologies satisfy a variety of nonmetal-lic composite designs in commercial and military aerospace applications, including flooring panels, ducting, vertical and horizontal stabilizers, wings, and even the fuselage.
This same chemistry, developed for aerospace applications, is now being used to produce lightweight bicycle frames, golf clubs, snowboards, racing cars, and musical instruments.
For the purpose of obtaining solvent-free epoxy acrylate latexes of good stability and excellent integrated performance, the epoxy acrylate latexes were fabricated using facile semi-continuous emulsion polymerization with varying amounts of epoxy resin and were modified by a silane coupling agent y-methacryloxypropyltrimethoxysilane (KH-570). The effects of epoxy resin and KH-570 amounts on the
performance of latexes and films were investigated from the aspects of particle size, morphology, tensile measurements, resistance properties, adhesion force, and thermal behavior. The results indicated that the acrylate monomers did graft onto the molecular chain of E-51 characterized by both epoxy value and Fourier transform infrared. Additionally, an emulsion of 80100 nm particle size with a narrow distribution was obtained. The latex films retain resistances to satisfactory water, acid, alkali, and alcohol while maintaining good thermal stability, adhesion force, and flexibility. The importing of KH-570 could reinforce the spatial structure and cross-linking density and then improve the tensile strength of the latex films properly while keeping other performances well. This work provides a facile pathway for the optimized performance for epoxy acrylate latexes, and represents a tendency for environmental protection [1].
Other examples of silanous modifications are modification of epoxy resin, silicon and glass surfaces with alkyl- or fluoroalkylsilanes for hydrophobic properties and modification of epoxy resins with functional silanes, polysiloxanes, silsesquioxanes, silica and silicates that we will discuss about.
Preparation of super hydrophobic materials inspired by nature has attracted a great scientific interest in recent decades. Some of these materials have hierarchical lotus-like structures, i.e. micro- and nano-objects coated by hydrophobic compounds. A major challenge of applying the super hydrophobic surfaces for the self-cleaning coatings preparation is their improved efficiency in varying atmospheric conditions, e.g. UV light. The objective of this research work was to investigate the effect of the different chemical structure and the surface free energy on the hydrophobic and tribo-logical properties of the alkylsilanes and fluoroal-kylsilanes deposited on silicon wafers, glass slides and epoxy resin. Tribological and hydrophobic properties of the modified surfaces were correlated with their chemical structures. Chemical structures of the depos-
ited materials were examined by using Fourier transform infrared (FT-IR) spectroscopy and hydrophobic properties were investigated by water contact angle (WCA) and surface free energy (SFE) measurements. The modified surfaces exhibited water contact angles of above 100° for the selected modifiers. It was noticed that the replacement of hydrogen atoms by fluorine atoms in alkyl chain caused an increase in the water contact angle values and a decrease in friction coefficients. The obtained results showed that the carbon chain length of a modifier and its chemical structure can strongly affect the hydrophobic and tribological properties of the modified surfaces. The highest values of WCA, lowest values of SFE and coefficient of friction were obtained for samples covered by fluorinated compounds. Moreover, some preliminary aging test was performed to give an insight into the effectiveness of deposited alkylsilanes and fluoroalkylsilanes coatings. After accelerated UV exposure, no significant changes in the chemical structure, hydrophobic and tribological properties of the modified surfaces were noticed. The samples degradation was not observed and hydropho-bic effect was maintained in UV light what can be promising in efficient self-cleaning coatings obtaining [2].
Epoxy resins are very important and widely used thermosetting polymers that find many practical applications. Very often their properties can be effectively modified by an addition of reactive silanes, polysilox-anes, silsesquioxanes, silica, montmorillonite, and other fillers. This review considers the literature concerning: (a) synthesis of carbofunctional silanes (CFS), polysiloxanes (CFPS) and polyhedral silsesquioxanes (POSS); (b) properties of neat epoxy resins and their composites and nanocomposites, obtained by modifications with reactive silanes, silicon containing monomers and polymers, and silica based fillers, enabling improvement of their mechanical properties, thermal and flame resistance as well as providing corrosion and antimicrobial protection [3].
In another thesis, an epoxy thiirane derivative of benzimidazolone-2 was synthesized. An addition of epoxy thiirane derivative of denzimidazolone-2 to epoxy rubber and epoxy composites was shown to increase their thermal stability, elasticity modulus, and cohesion and adhesion strengths, especially at higher test temperatures. The effect depends on the concentration of additive, hardening temperature, type of rubber, and other factors [4].
The influence of epoxy imide cycloaliphatic epoxy resin EPOX01 on the rheological properties of the epoxy amine system was investigated. The effect of the amount of amine hardener for solidification process of modified system is evaluated. It is shown that the use of epoxy imide cycloaliphatic resin allows one to obtain materials with improved technological characteristics of film technology (RFI) [5].
Two different experiments were conducted on increasing conductivity: Through-thickness thermal conductivity enhancement of graphite film/epoxy composite via short duration acidizing modification
and improved thermal conductivity of epoxy composites using a hybrid multi-walled carbon nanotube/mi-cro-SiC filler.
Graphite films have excellent in-plane thermal conductivity but extremely low through-thickness thermal conductivity because of their intrinsic inter-layer spaces. To improve the inter-layer heat transfer of graphite films, we developed a simple interfacial modification with a short duration mixed-acid treatment. The effects of the mixture ratio of sulfuric and nitric acids and treatment time on the through-thickness thermal properties of graphite films were studied. The modification increased the through-thickness thermal conductivity by 27% and 42% for the graphite film and its composite, respectively. X-ray photoelectron spectros-copy, X-ray powder diffraction, and scanning electron microscopy results indicated that the acidification process had two competing effects: the positive contribution made by the enhanced interaction between the graphite layers induced by the functional groups and the negative effect from the destruction of the graphite layers. As a result, an optimal acidification method was found to be sulfuric/nitric acid treatment with a mixture ratio of 3:1 for 15 min. The resultant through-thickness thermal conductivity of the graphite film could be improved to 0.674 W/mK, and the corresponding graph-ite/epoxy composite shows a through-thickness thermal conductivity of 0.587 W/mK. This method can be directly used for graphite films and their composite fabrication to improve through-thickness thermal conductivity [6].
By adding 6 wt. % multi-walled carbon nanotubes (MWCNTs) or 71.7 wt. % micro-SiC to an epoxy, resin the thermal conductivities of the composites reached maxima that were respectively 2.9 and 20.7 times that of the epoxy alone. To further improve the thermal conductivity a method that partially replaces microfiller with nanofiller was used, and a thermal conductivity, 24.3 times that of the epoxy, was obtained with 5 wt.% MWCNTs + 55 wt.% micro-SiC [7].
For enhancing the surface electric withstanding strength of insulating materials, epoxy resin (EP) samples are treated by atmospheric pressure plasma jet (APPJ) with different time interval from 0 to 300s. Helium (He) and tetrafluoromethane (CF4) mixtures are used as working gases with the concentration of CF4 ranging 0%-5%, and when CF4 is ~3%, the APPJ exhibits an optimal steady state. The flashover withstanding characteristics of modified EP in vacuum are greatly improved under appropriate APPJ treatment conditions. The surface properties of EP samples are evaluated by surface roughness, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. It is considered that both physical and chemical effects lead to the enhancement of flashover strength. The physical effect is reflected in the increase of surface roughness, while the chemical effect is reflected in the graft of fluorine groups [8].
This paper presents corrosion and abrasion resistance of an epoxy system modified by using a synthesized epoxy terminated polybutadiene (ETPB) resin with good toughening properties. The effect of this
modification on the hardness, abrasion, thermal and corrosion protection performance of the resultant modified coatings was investigated. Pendulum hardness test showed that the incorporation of ETPB into epoxy matrix increased damping energy of the system. Taber experiment showed that rubber modification increased abrasion resistance of epoxy coatings. Thermal gravimetric analysis (TGA) of samples showed that the thermal resistance of ETPB modified epoxy coatings was almost the same as that for the next one. The corrosion protection performance of rubber modified and unmodified epoxy coatings were investigated using electrochemical impedance spectroscopy (EIS) in 3.5% sodium chloride solution for a period of 90 days. EIS studies showed that both coatings remained intact with good corrosion resistance properties. Film resistance of unmodified and ETPB modified epoxy coatings after 90 days of immersion were found to be 2.59 x 1010 Q cm2 and 2.70 x 1010 Q cm2, respectively. The addition of hydrophobic butadiene rubber into epoxy resin increased the water contact angle from 77° to 85°. This increment in hydrophobicity decreased the water uptake of modified epoxy coating [9].
A novel liquid crystalline epoxy monomer, 1,10-bis [4-(2,3-epoxy propoxyphenyleneininomethyl)]-2,20dimethylbiphenylene (BMPE) was synthesized and characterized by infrared (IR) and Nuclear magnetic resonance (NMR) spectroscopy. The effect of BMPE content on mechanical and thermal properties of its blends with Diglycidyl Ether of Biphenol A (DGEBA) was investigated. BMPE presented a Schlieren texture in the range of 150 to 2158C as observed by differential scanning calorimeter (DSC) and polarizing optical microscope (POM). The improvement of mechanical properties of DGEBA modified with BMPE was achieved without sacrificing thermal resistance. Scanning electronic microscopy (SEM) graphs of fracture surfaces of the cured blends showed that microfiber-like structure formed in the cured blends, which would be a result of self-oriented alignment of azomethine mesogen component. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 105: 18611868, 2007 [10].
In this study, acrylated soybean oil (AESO) was used as a modifying agent for DGEBA-type epoxy resin (ER). The structure of modified epoxy resins (MERs) cured with various hardeners (SAc-sebacic acid, MNA-methyl nadic anhydride, PhA-phthalic anhydride, MA-maleic anhydride, SA-succinic anhydride, cycloaliphatic polyamine Examine PC 17, MXDA-m-xylenediamine, MI-2-methylimidazole and polyamide type Crayamid) were characterized by Fourier transform infrared spectroscopy (FTIR). Atomic force microscopy (AFM) and SEM were used to determine the microstructures of some M-ERs. DSC test was conducted to study the effects of hardeners on the Tg of the M-ERs. The influence of the modifying agent and hardeners on the curing process was studied through FTIR spectroscopy, and the curing degrees of M-ERs were determined to be over 94%. To investigate the effects of the curing agents, a comparative study was also performed on the mechanical properties of neat ER, such
as the tensile strength and hardness. Comparison between the mechanical properties of the epoxy systems demonstrated that the neat ER system had a higher tensile strength and e-modulus than that of M-ERs, which is in contrast to the elongation at break. Higher tensile strength values of 58 MPA and 53 MPa were observed for M-ERs cured with MNA and MXDA curing agents, respectively. A comprehensive study of the mechanical and water sorption properties of M-ERs illustrated that for an epoxy system modified with AESO in 50 wt.%, MNA and MXDA were a more effective hardeners. Coatings obtained from M-ERs cured with anhydride type hardeners were determined to be highly resistant to acidic corrosive media [11].
Experiments were conducted for the improvement of mechanical properties of epoxy resins. One of them is developing a Sealing Material: Effect of Epoxy Modification on specific physical and mechanical properties, another is improved interfacial properties of carbon fiber/epoxy composites through grafting polyhedral oligomeric silsesquioxane on carbon fiber surface
To develop a matched sealing material for socket rehabilitation of grey cast iron pipes, an epoxy resin is modified by the addition of different components to improve the flexibility. Three different modifications are made by adding ethylene-propylene diene monomer (EPDM) rubber powder, reactive liquid polymer (ATBN) and epoxidized modifier. In this paper the effect of the modification method as well as the influence of absorption of water on the mechanical and physical properties are analyzed in terms of: tensile strength, modulus of elasticity, adhesion performance, pressure resistance, glass transition temperature and water content. A comparison with neat epoxy shows for all materials that the modulus of elasticity and strength decrease. Unlike other tested modification methods, the modification with rubber powder did not enhance the flexibility. All materials absorb water and a plasticization effect arises with further changes of mechanical and physical properties. The application of the sealant on the grey cast iron leads to a reduction of the strain at break (in comparison to the common tensile test of the pure materials) and has to be evaluated. The main requirement of pressure resistance up to 1 MPa was tested on two chosen materials. Both materials fulfill this requirement [12].
Carbon fibers were grafted with a layer of uniform octaglycidyldimethylsilyl POSS in an attempt to improve the interfacial properties between carbon fibers and epoxy matrix. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and dynamic contact angle analysis were performed to characterize the carbon fibers. AFM results show that the grafting of POSS significantly increased the carbon fiber surface roughness. XPS indicates that oxygen-containing functional groups obviously increased after modification. Dynamic contact angle analysis shows that the surface energy of modified carbon fibers is much higher than that of the untreated ones. Results of the mechanical property tests show that interlaminar shear strength (ILSS) increased from 68.8 to 90.5 MPa and impact
toughness simultaneously increased from 2.62 to 3.59 J
[13].
To increase the strength of an adhesive joint whose adherend is composed of a carbon fiber/epoxy composite, the surface of the adhered is reinforced with randomly oriented aramid fiber felt before the full cure of the adherent. With this smart cure cycle, the aramid fibers are exposed from the adhered, promoting a bridging effect between the fibers and the adhesive. The cured carbon fiber/epoxy composite material, on which the aramid fiber felt is placed, is co-cure bonded with a smart cure cycle developed in this work. The improvement of the adhesive bonding strength due to the ara-mid fiber felt is measured with the single-lap shear test of adhesively bonded joints. Additionally, the flexural strength of the carbon fiber/epoxy composite adhered with the co-cure bonded aramid fiber felt is measured
[14].
A bifunctional epoxy resin was modified by using a CO2 fixation solution process in the presence of tetra n-butyl ammonium bromide (TBAB) as catalyst and the modified treated resin was treated by cloisite 30B as nano additive. The Unmodified epoxy resin (UME), CO2fixated modified epoxy resin (CFME), and CFME/clay nano composite (CFMEN), were cured by diethylenetriamine (DETA). A cycloaliphatic compound as a reactive diluent was used to control the viscosity of high viscose CFME. The exfoliation of or-ganoclay in UME and CFME was investigated by X-ray diffraction and activation energy was computed using the advanced integral isoconversional method. The activation energy dependency demonstrated that the mechanism of UME curing did not change in the presence of nanoclay. In contrast, the CO2 fixation results showed a significant change in the activation energy dependency. The Thermal stability parameters include the initial degradation temperature (IDT), the temperature at the maximum rate of weight loss (Tmax), and the decomposition activation energy (Ed) were determined by thermal gravimetry analysis. Dynamic mechanical thermal analysis measurements showed that the presence of organoclay in CFME increases the Tgof nano composite in contrast to UME. The fracture roughness of UME, CFME and CFNE were determined by scanning electron microscope. The exfoliated UME/1%clay nanocomposite was confirmed by TEM image [15].
The curing reaction of formulations of diglycidyl ether of bisphenol A (DGEBA) and tetrahydrophthalic anhydride (THPA) catalyzed with a tertiary amine and containing sepiolite and/or hyperbranched poly(ester) has been studied by means of DSC, and the effect of each additive has been evaluated. The resulting coatings have been characterized by DMTA, TGA and also the shrinkage during the curing process has been determined. The influence of the additives in the toughness of the resulting coatings has been determined by performing standardized impact tests and observing the fracture surfaces by SEM. The values of impact strength have been correlated to the morphology of the samples by means of TEM. Also microhardness of the cured materials has been measured [16].
In this research, epoxy toluene oligomer (ETO) was synthesised from toluene and epichlorhydrin,
which was used as co-matrix in 50 wt.% with commercial epoxy resin (ER). Its chemical structure was characterised with FTIR spectroscopy and chemical analyses. ETO was found as an effective flame retardant for ER. Modification of ER with ETO in 50 wt.% increased percentage elongation at break of neat ER about 67 times. The rigid filler used in epoxy polymer matrix was the modified and unmodified sepiolite. The appropriate sepiolite amount in all cases was determined to be 5 wt.%. Scanning electron microscopy (SEM) was used for characterisation of surface and cross sections of the composites to verify the results. Modification of sepiolite increases the T5, T10, and T50 of neat ETO-ER by 10, 7, and 5 °C, respectively. Surface hardness and tensile strength of all composites were higher than those of neat ETO-ER polymer matrix. ETO-ER/modified sepiolite coating showed the best adhesion results and exhibited perfect resistance to 3% NaCl and 10% NaOH solutions [17].
To increase the strength of an adhesive joint whose adherend is composed of a carbon fiber/epoxy composite, the surface of the adherend is reinforced with randomly oriented aramid fiber felt before the full cure of the adherend. With this smart cure cycle, the aramid fibers are exposed from the adherend, promoting a bridging effect between the fibers and the adhesive. The cured carbon fiber/epoxy composite material, on which the aramid fiber felt is placed, is co-cure bonded with a smart cure cycle developed in this work. The improvement of the adhesive bonding strength due to the aramid fiber felt is measured with the single-lap shear test of adhesively bonded joints. Additionally, the flexural strength of the carbon fiber/epoxy composite adherend with the co-cure bonded aramid fiber felt is measured [18].
Hybrid composites with rubber properties were made from an epoxy modified with either 2.5 phr (parts per hundred) or 15 phr carboxyl terminated poly(buta-diene-co-acrylonitrile) (CTBN). Organo-montmorillo-nite clay added ranged from 0 to 5 phr. Morphology including that of worn surfaces was examined, dynamic mechanical analysis performed and impact resistance determined. Dynamic friction and wear were determined using a pin-on-disc tribometer at dry sliding conditions. Storage modulus of the material containing 2.5 phr CTBN is higher than for 15 phr CTBN, a result of smaller CTBN droplets in the former. All composites have higher values of the Izod impact strength than the neat epoxy resin. Dynamic friction of the hybrids is not influenced by addition of clay whereas the wear resistance depends on the clay concentration. The wear rates at the applied load of 5 N for EP/15-CTBN hybrids are much larger than for EP/2.5-CTBN nanocom-posites. This result can be related to the lower glassy storage modulus of EP/15-CTBN as compared to EP/2.5-CTBN. The addition of less than 5 phr clay improves the wear resistance at both 5 and 10 N normal loads. 1 phr clay in the EP/2.5-CTBN matrix is recommended as the optimum composition for improving both mechanical and tribological properties of the epoxy resin [19].
A high performance repair materials for concrete is prepared using epoxy resin as a base resin and asphalt
as a modifier, respectively. The influence of the asphalt content, freeze-thaw circles, and chemicals on the structure and properties of the repair materials is investigated in detail in this work. Results show that the epoxy repair materials modified with 10 phr of asphalt has the excellent mechanical property, and the com-pressive strength and tensile shear strength can reach 56.6 MPa and 5.9 MPa, respectively. The compressive strength further increases while the weight change for all samples is below 1 wt. % when the repair materials suffer 30 freeze-thaw circles and chemicals soakage at 80 °C for 2 weeks, indicating that the asphalt-modified epoxy repair materials have the outstanding water, acid, and alkaline resistance and salt tolerance. Therefore, a kind of asphalt-modified epoxy repair materials with excellent freeze-thaw resistance is developed in this research [20].
Epoxy resins are inherently brittle. Thus they are toughened with reactive liquid rubbers or core-shell elastomers. Surface-modified silica nanoparticles, 20 nm in diameter and with a very narrow particle size distribution, are available as concentrates in epoxy resins in industrial quantities since 10 years. Some of the drawbacks of toughening, like lower modulus or a loss in strength can be overcompensated when using nano-silica together with these tougheners. Apparently there exists a synergy as toughness and fatigue performance are increased significantly. In this article the literature published in the last decade is studied with a focus on mechanical properties. Results are compared and the mechanisms responsible for the property improvements are discussed [21].
The presence of polyamine groups on the surface of dielectric resins potentially improves the adhesion with electrochemically deposited metals. In this article, first cyanuric chloride is covalently bound to the surface hydroxyl groups of the epoxy resin. The remaining reactive sites on the coupled cyanuric chloride molecule are then used to anchor polyamines. New data on the triazine coupling is presented. The surface reactions are monitored and characterized by means of ATR-IR, SEM-EDS, XPS and ToF-S-SIMS [22].
A commercial epoxy diglycidylether of bisphenol-A (DGEBA) was modified by adding fluorinated poly(aryl ether ketone) fluoropolymer and in turn metal micro powders (Ni, Al, Zn, and Ag) and coated on mild steel. Two curing agents were used; triethylenetetra-mine (a low temperature curing agent) and hexameth-ylenediamine (a high temperature curing agent) for understanding the curing temperature effect on the properties. Variations in tribological properties (dynamic friction and wear) and surface energies with varying amounts of metal powders and curing agents were evaluated. When cured at 30°C, dynamic friction and wear decrease significantly due to phase separation reaction being favored between the fluoropolymer and the epoxy. However, when cured at 80°C, friction and wear increase; this can be explained in terms of a crosslink-ing reaction favored at that temperature. There is a significant decrease in surface energies with the addition of modifiers [23].
Hydroxy terminated PFPE were chain extended with short PCL segments in order to enhance the compatibility towards the epoxy resin. The obtained PFPE-PCL block copolymers were used as additives to modify toughness of a UV curable bisphenol-A-based epoxy coating. A certain degree of phase separation was achieved during UV curing. The morphology of the obtained cured materials depends on the polycapro-lactone PCL length. The perfluoropolyether PFPE additive, without any PCL segment (additive TX), clearly showed a biphasic morphology with separated domains within 50-100 ^m. By increasing the PCL segment it was not identified any second distinct phase. It was shown that the addition of TX additive can generate a strong phase separation and this allowed to achieve an improvement of the toughness properties of the cured samples without affecting the thermo-mechanical properties [24].
This paper describes the influence of polydopa-mine and polyamine surface modifications of an etched epoxy cresol novolak (ECN) resin on the initial electro-less copper deposition. Three different strategies to introduce polyamines on a surface in aqueous environment are applied: via polyethyleneimine adsorption (PEI), via polydopamine and via polyamines grafted to polydopamine. Next, the influence of these surface modifications on the catalytic palladium activation is investigated through X-ray photoelectron spectroscopy (XPS) analysis. Finally, the initial electroless copper deposition on modified epoxy surfaces is evaluated using SEM and Energy Dispersive Spectroscopy (EDS). Grafted polyamines on polydopamine surface modifications result in a large increase of the initial deposited copper [25].
Abstract-Composites of polymers and nanoparti-cles continue to find increasing applications from biomedical to electronics to transport systems. Nanostruc-tured carbon nanoparticles (CNPs) having geometries from 0D to 3D are important functional additives for polymers, having great potential to produce composite materials with a range of enhanced properties including mechanical, optical, electrical and thermal. However, these possibilities have not been fully realised due to the difficulties associated with CNP dispersion in and their interaction with polymer matrices across the length scales. The surfaces of CNPs are intrinsically chemically inert and hydrophobic, and they tend to form agglomerates or bundles. Therefore, surface func-tionalisation of CNPs becomes a critical pre-requisite in the fabrication of polymer nanocomposites. Various functionalisation methods have been developed including, chemical, mechanochemical, electrochemical, and irritation reactions in order to activate the carbon surface, which subsequently interact with polymers through covalent bonding or non-covalent interactions. Wet-chemistry methods consume large amounts of organic solvents, hazardous chemicals, require multi-step purification with typically low yields. Mechanochem-istry techniques such as ball milling can produce edge-functionalised CNPs at the expense of reduced aspect ratio. In contrast, cold plasma treatment offers a simple, clean, solvent-free, and scalable technique for modify-
ing CNPs with variable functional groups. Recent developments in plasma-treated CNPs have driven its applications extensively in epoxy-based composites. Amino-functionalisation of CNPs is particularly favourable, as the amine group offers a rich reaction platform to enhance the activity of the CNP as both modifier and crosslinker for epoxy resins. Research activity in this area is under development but growing rapidly. In this review, we introduce the working mechanism for plasma functionalisation of CNPs, and compare this approach with the efficiency and effectiveness of wet-chemistry methods. The discussion will focus on amine-functionalised CNPs (carbon nanotubes, gra-phene/graphene oxide and carbon fibre) and their use in the modification of the properties of epoxy resins [26].
A commercial diglycidylether of bisphenol-A (DGEBA) epoxy was modified by blending with a flu-oroepoxy oligomer diglycidyl of trifluoromethyl aniline (DGTFA), with the content of DGTFA 2.5-20 phr. Thermogravimetry shows that the incorporation of tertiary amines results in a reduction in thermal stability. The storage modulus in the glassy state increases significantly as a function of DGTFA content due to anti-plasticization. Higher wear resistance and lower dynamic friction are achieved by incorporation of DGTFA. At least for the range of this study, while increasing the amount of DGTFA, both wear rate and dynamic friction are reduced due to the formation of a protective transfer film (third body). The product of flexural strength and strain at deflection point is found to correlate with the reduction in wear rate [27].
Mixtures of diglycidylether of bisphenol A (DGEBA) resin and commercially available hyper-branched polyester (HBP) Boltorn H30 were cured by anhydride to covalently bond the hydroxyl end groups in HBP with the epoxy resin. The curing mixtures were investigated by Differential Scanning Calorimetry (DSC) to study the curing evolution and to evaluate the kinetic parameters. DSC studies suggested that HBP could increase the curing rate of epoxy/anhydride systems at low conversions, but it produced a decelerative effect in the last stages of the curing. The influence of the HBP content and the proportion of anhydride on the curing conversions were discussed in detail. The addition of a tertiary amine was proved to decrease the curing temperatures. By Fourier Transform Infrared Spec-troscopy (FTIR) the reaction of hydroxyl groups during the whole process was confirmed. By the determination of the conversion at the gelation, we could prove that it increased on increasing the proportion of HBP in the reactive mixture. By Thermomechanical Analysis (TMA) we could determine a reduction of the shrinkage after gelation [28].
This paper studies the modification of petroleum bitumen with epoxy resin. Different amounts of epoxy were doped into bitumen with 50/70 penetration grade and variations in viscosity as a function of temperature and additive concentration were determined. The effects of the epoxy additive were examined by rheome-ter, penetration, softening point, DSR (dynamic shear rheometer), DSC (differential scanning calorimeter), RTFOT (rolling thin film oven test), PAV (pressure ag-
ing vessel), BBR (bending beam rheometer) and surface tension tests. Adhesion and stability of bitumen aggregate mixtures prepared using original and modified bitumen were compared using Nicholson stripping and Marshall tests. The optimum dosage of the additive yielding the best rheological and performance properties was found to be 2% (w/w). Appreciable decrease in the formation of rutting, bleeding, stripping and cracking of modified bitumen may be obtained through epoxy addition [29].
Analysis of experimental data showed that KO-922 renders plasticizing effect upon polymer composite material. The dependencies are clearly pronounced. The decrease in the dynamic viscosity of the formulations at maximum concentration of the additive ranges from 48 to 61 %. The results obtained in Fig. 1 regularities are explained on the basis of the current understanding of polymer structure .Epoxy polymers have a static coil-shaped conformation with a strong intertwining of chains at the molecular level. When a small amount of KO-922 is added to the resin, the fictional forces between congregations and certain molecules of the epoxy oligomer are decreased, which in turn leads to a sharp decrease in dynamic viscosity. With a further increase in concentration of KO-922, aggregates are formed from epoxy oligomers and additives. At the same time, the plasticity of the epoxy resin slows down. Further increase in the concentration of additive content in the binder leads to viscosity of the system. It should be noted that, given the equality of the degree of filling for all compositions ( in this case ration is equal to Polymer/Filler =1/10),the specific surface of the filler has a determining effect on the mobility of the mixture, which is: FFCI-4.39 m2/kg, for FWCI-10.31 m2/kg for serpentinite-7.62 m2/kg).
• The workability of mixtures and forming of products based on a modified polymer binder is facilitated using plasticizers in the form of silica-organic fluids.
• The nature of the dependence of dynamic viscosity of mixtures on the concentration of the silica-organic plasticizer is established. The optimum content determined in the range of 2.5 to 3 % by mass.
• The optimum values of the content of the silica-organic plasticizer are determined, at which the wetting of the filler by the binder has the greatest impact on the technological properties of the material. The most effective concentration is the content of the plasticizer in the range of 0.1-3 % by mass.
Numerous studies have been carried out in our department to improve the properties of the epoxide oli-gomer. [29] .
The modification of the epoxide oligomer was used in the study of the amide-containing compound. As a result of the modification, epoxide oligomer with high physical and mechanical properties has been obtained.
Infrared spectra of the modified epoxidian oligomer are plotted. Figure 1 shows the spectrum of the unmodified epoxide oligomer, and Figure 2 shows the modified epoxide oligomer [30].
It is clear from this spectrum that the strips characteristic of amide-containing compounds in the range of 3500 to 3200 cm-1 will almost disappear. This is caused by a chemical reaction between epoxide
S3 R
oligomerization and the resulting epoxide amide derivative. This is clearly visible in the range 31002800 cm-1 .
Fig. 2. Infrared spectrum of modified epoxy oligomer
Thus, the investigation of the infrared spectrum of the epoxide oligomer with the amide-containing compound enables the identification of the nature of the interaction between the components, which functional groups participate in these reactions.
It has been determined that, due to the combination of amide-containing compound and epoxy oligomer, the characteristic strips belonging to the imine group disappear. The construction of the modified modifier compound into the oligomer is accompanied by the formation of C-N communication.
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5. N. N. Panina, T. A. Grebeneva, Ya. M. Gurevich, A. I. Tkachuk, and M. A. Kim "Modification of Epoxy Binders Using Cycloaliphatic Epoxy Imides", Moscow, March 13, 2013
6. Han Wang, Shaokai Wang, Weibang Lu, Min Li Yizhou Gu, Yongyi Zhang, Zuoguang Zhang "Through-thickness thermal conductivity enhancement of graphite film/epoxy composite via short duration acidizing modification" Advanced Materials Division China, 13 February 2018.
7. Tianle Zhou, Xin Wang, Xiaoheng Liu, Dangsheng Xiong "Improved thermal conductivity of epoxy composites using a hybrid multi-walled carbon nanotube/micro-SiC filler" China, 26 November 2009.
8. Sile Chen Shuai Wang, Yibo Wang, Baohong Guo, Guoqiang Li, Zhengshi Chang Guan-JunZhang "Surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet for flashover withstanding characteristics improvement in vacuum", Accepted 30 March 2017,
9. Hossein Yahyaei, Morteza Ebrahimi, Hamed Vakili, Tahami, Ehsan R.Mafi, Esmaeil Akbarinezhad
"Polymer Engineering and Color Technology Department", Amirkabir University of Technology, P.O. Tehran, Iran, 19 September 2017.
10. Zongyong Gao, Yingfeng Yu, Yuanze Xu, Shanjun Li "Synthesis and Characterization of a Liquid Crystalline Epoxy Containing Azomethine Mesogen for Modification of Epoxy Resin"1 March 2007
11. Suheyla Kocaman, Gulnare Ahmetli "A study of coating properties of biobased modified epoxy resin with different hardeners" Selcuk University, Faculty of Engineering, Dept. of Chemical Engineering, Konya, Turkey,7 April 2016
12. Christoph Schoberleitner 1,*, Vasiliki-Maria Archodoulaki 1, Thomas Koch 1, Sigrid Lüftl 1, Markus Werderitsch 2 and Gerhard Kuschnig 2 Developing a Sealing Material: "Effect of Epoxy Modification on Specific Physical and Mechanical Properties" Vienna, Austria 27 November 2013
13. Feng Zhao, Yudong Huang "Improved interfacial properties of carbon fiber/epoxy composites through grafting polyhedral oligomeric silsesquioxane on carbon fiber surface" China, 3 September 2010.
14. Ilbeom Choi, Dai GilLee "Surface modification of carbon fiber/epoxy composites with randomly oriented aramid fiber felt for adhesion strength enhancement", Republic of Korea, 25 January 2013.
15. Morteza Khoshkish, Hosein Bouhendi "Modification of bifunctional epoxy resin using CO2 fixation process and nanoclay" Iran Polymer & Petrochemical Institute, 2 June 2014.
16. D.Foix, M.T.Rodriguez, F.Ferrando, X.Ramis, A.Serra "Combined use of sepiolite and a hyper-branched polyester in the modification of epoxy/anhy-dride coatings" University Politecnica de Catalunya, Barcelona, Spain, 10 August 2012.
17. Gulnare Ahmetli, Huseyin Deveci, Ulku Soydal, Asli Seker, Refika Kurbanli
18. "Coating, mechanical and thermal properties of epoxy toluene oligomer modified epoxy resin/sepio-lite composites" Konya, Turkey, 26 April 2012.
19. Ilbeom Choi Dai Gil Lee" Surface modification of carbon fiber/epoxy composites with randomly oriented aramid fiber felt for adhesion strength enhancement" Republic of Korea, 25 January 2013.
20. Wunpen Chonkaew, Narongrit Sombat-sompop ,Witold Brostow "High impact strength and low wear of epoxy modified by a combination of liquid carboxyl terminated poly(butadiene-co-acrylonitrile) rubber and organoclay", Bangkok, Thailand , 6 August 2012.
21. Yanping Wang, Jiaofeng Ye, Yanhua Liu, Xiaohu Qiang , Libang Feng "Influence of freeze-thaw cycles on properties of asphalt-modified epoxy repair materials" China, 29 January 2013.
22. Stephan Sprenger, Evonik Hanse "Epoxy resins modified with elastomers and surface-modified silica nanoparticles", Germany, 18 June 2013
23. David Schaubroeck, Johan De Baets, Tim Des-met , Peter Dubruel, Etienne Schacht, LucVan Vaeck, AndréVan Calster "Surface modification of an epoxy resin with polyamines via cyanuric chloride coupling" Belgium, 9 April 2010.
24. Witold Brostow, Madhuri Dutta, Piotr Rusek "Modified epoxy coatings on mild steel: Tribology and surface energy", Poland, September 2010.
25. M. Sangermano, M. Messori, A. Rizzoli, S.Grassini "UV-cured epoxy coatings modified with perfluoropolyether-based materials" Italy, 31 March 2010.
26. David Schaubroeck, Lothar Mader Nathalie De Geyter Rino Morent Peter Dubruel JanVanfleteren "Surface modification of an epoxy resin with polyam-ines and polydopamine: The effect on the initial elec-troless copper deposition"
27. Ghent, Belgium, 20 March 2014.
28. Ashraful Alam, Chaoying Wan, Tony Mc Nally "Surface amination of carbon nanoparticles for modification of epoxy resins: plasma-treatment vs. wet-chemistry approach", Australia, 6 October 2016.
29. Witold Brostow, Wunpen Chonkaew, Kevin P.Menard, Thomas W.Scharf "Modification of an epoxy resin with a fluoroepoxy oligomer for improved mechanical and tribological properties", United States, 11 December 2008.
30. David Foix , YingfengYu, Angels Serra "Study on the chemical modification of epoxy/anhydride thermosets using a hydroxyl terminated hyperbranched polymer" China, 12 February 2009.
31. Meltem Çubuk, Metin Gürü, M. Kûrçat Çubuk "Improvement of bitumen performance with epoxy resin" Turkey, 18 January 2009.
32. Musayeva A.Yu. /Development of composition materials on basis of epoxy resin, filled with wastes/ «European Journal of Technical and Natural Sciences» 2017, №2 p. 58-61
33. Musayeva A.Yu./ impact of the filler on mechanical properties of the epoxy based composite material/ American Journal of Science and Technologies 2018, No.1. (28), p.268-274.
