Belkis Ustamehmetoğlu, Nesrin Köken, Nilgun Kizilcan, Ahmet Akar and Şebnem Tayyar
The purpose of this paper is to produce non-conductive copolymers of N-vinyl carbazole (NVCz) and methyl ethyl ketone formaldehyde resin (MEKFR) by the electroinduced Ce (IV…
Abstract
Purpose
The purpose of this paper is to produce non-conductive copolymers of N-vinyl carbazole (NVCz) and methyl ethyl ketone formaldehyde resin (MEKFR) by the electroinduced Ce (IV) polymerization method and the electrochemical oxidization of the formed copolymer to produce their conductive green form. The non-conductive and conductive copolymers were characterized by using Fourier transform infrared, solid-state conductivity and spectroelectrochemical, chronoamperometric, cyclovoltammetric and electrochemical impedance spectroscopic measurements.
Design/methodology/approach
The chronoamperometric electropolymerization of white, insulator form of the copolymer of NVCz and MEKFR (copolymer 1) on to Pt electrode was carried out and the green coloured film of the MEKFR-ox-NVCz copolymer (copolymer 11) was produced in the doped and conductive form. All reactions were performed in dichloromethane containing 0.1 M BU4NClO4. Copolymer 11 films obtained on the surface of the working electrode were removed and washed in acetonitrile and dried at room temperature before characterization. The results were compared with the copolymer obtained by electrochemical oxidation of MEKF-R and NVCz (copolymer 2).
Findings
The insulating copolymer of NVCz and MEKFR (copolymer 1) was produced by the electroinduced Ce (IV) polymerization method and converted into the conductive form electrochemically on the surface of the Pt electrode (copolymer 11). The polymers were characterized by electrochemical, spectrophotometric and conductivity measurements. The ionization potentials, optical band gap, peak potentials Ep, doping degree and specific capacitance of the copolymer 11 were obtained. The conductivity of the copolymer 11 is lower than the PNVCz and higher than the copolymer obtained by electrochemical oxidation of MEKF-R and NVCz (copolymer 2). The copolymer 11 has a lower onset potential than PNVCz and the copolymer 1 and slightly higher band gap than PNVCz. The capacitive behaviours of the copolymer 11 were very close to PNVCz.
Research limitations/implications
This study focuses on obtaining a green and conductive form of the copolymer of NVCz and MEKFR with the electrochemical method by using a white and insulator form of the same copolymer.
Practical implications
This work provides technical information for the synthesis of conducting copolymer of NVCz and MEKFR.
Social implications
These copolymers may be in the field of PNVCz applications such as photoconductivity and corrosion inhibition.
Originality/value
Electroinduced Ce (IV) MEKFR redox system was applied for the polymerization of NVCz monomer to produce the copolymer 1. The conductive copolymer 11 was synthesized through electrochemical oxidative coupling of the carbazole groups of the copolymer 1.
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Yusuf Yivlik, Nilgun Kizilcan and Ahmet Akar
Cyclohexanone–formaldehyde resin (CFR) was in situ modified with isocyanuric acid (ICA) in the presence of hydrochloric acid or p-toluenesulfonic acid by condensation…
Abstract
Purpose
Cyclohexanone–formaldehyde resin (CFR) was in situ modified with isocyanuric acid (ICA) in the presence of hydrochloric acid or p-toluenesulfonic acid by condensation polymerization. The purpose of this study is to produce isocyanuric acid-modified ketonic resins that have higher melting and decomposition temperature, and to use the produced resin in the production of fire-retardant polyurethane.
Design/methodology/approach
Two methods were used for in situ preparation of ICA-modified CFR in the presence of an acid catalyst. Method I: cyclohexanone, paraformaldehyde and ICA were mixed, and then an acid catalyst was added to form the modified CFR. Method II: ICA and formalin were mixed to produce N, N, N-trihydroxymethyl isocyanurate, and then water was removed under vacuum. The produced N, N, N-trihydroxymethyl isocyanurate solution was mixed with cyclohexanone and paraformaldehyde, then an acid catalyst was slowly added to this mixture to obtain ICA-modified CFR.
Findings
CFR was prepared in the presence of an acid catalyst. The product, CFR, has a dark red colour. The resulting resins have similar physical properties with the resin prepared in the presence of a basic catalyst. The solubility of ICA-modified CFR is much different than CFR in organic solvents.
Research limitations/implications
This study focuses on obtaining an ICA-modified ketonic resin. Cyanuric acid has the form of an enolic structure under a basic condition; therefore, it cannot give a product with formaldehyde under basic conditions. The modification experiments were carried out in acidic conditions.
Practical implications
This study provides technical information for in situ modification of ketonic resin in the presence of acid catalysts. The resins may also promote the adhesive strength of the coating and provide corrosion inhibition on metal surfaces for a coating. The modified resins may also be used in the field of fire-retardant polyurethane applications.
Social implications
These resins may be used for the preparation of non-toxic fire-retardant polyurethane foam. Polyurethane containing ICA-modified resin may exhibit better fire-retardant performance because of the incorporation of ICA molecule into the polyurethane structure.
Originality/value
ICA-modified CFRs have been synthesized in the presence of an acid catalyst, and the ICA-modified resin was used to produce fire-retardant polyurethane.
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Esin Ateş, Nilgün Kizilcan and Merve İstif
The purpose of this paper is to synthesise an electro-active monomer containing ketonic resins and then to investigate the redox reaction between Fe+3 and bound thiophene in…
Abstract
Purpose
The purpose of this paper is to synthesise an electro-active monomer containing ketonic resins and then to investigate the redox reaction between Fe+3 and bound thiophene in comonomer. First, thiophene-functionalised ketonic resins were synthesised by esterification reaction of thiophene-2-carbonyl chloride (ThCCl) and hydroxyl groups of cyclohexanone formaldehyde resin (CFR). Thiophene-containing cyclohexanone formaldehyde resin (Th-CFR) was then polymerised by ferric salt. The structures of the specimens were characterised by means of Fourier transform infrared and Proton – Nuclear Magnetic Resonanse (1H-NMR) spectroscopy. Thermal properties of the samples were determined with differential scanning calorimeter. Molecular weights of the specimens were determined by gel permeation chromatography. The obtained samples were also characterised morphologically by scanning electron microscope.
Design/methodology/approach
Synthesis of Th-CFR comonomers by a combination of condensation polymerization and chemical oxidation polymerisation processes is described. First, Th-CFR units were prepared by direct condensation reaction of thiophene-2-carbonyl chloride (ThCCl) and hydroxyl groups of CFR. Then, the chemical oxidation (CO) of Th-CFR in the presence of anhydrous iron (III) chloride salt (FeCl3) was performed in chloroform (CHCl3)/acetonitrile mixture solutions at room temperature.
Findings
The important structural factor determined quantitatively for Th-CFR is the CFR/ThCCl ratio after reaction. The effect of the mole ratio effect of ThCCl and ketonic resin on the solubility, molecular weight, Tm and Tg values of the comonomers (Th-CFRs) were investigated.
Research limitations/implications
The ferric ion (Fe+3) has a standard oxidation potential. Furthermore, FeCl3 can react with thiophene to produce a cation radical. FeCl3 cannot react with hydroxyl groups of ketonic resins. When ferric is used for in situ chemical oxidation application at relatively low temperatures (e.g. < 20°C), the oxidation reactions are usually less aggressive.
Practical implications
This work provides technical information for the synthesis of conducting block copolymer and for the synthesis of chain-extended resins. The modified resins contain electro-active monomer as thiophene. The chemical oxidation system has been used to polymerise these thiophene groups and resins with much higher molecular weight might be produced. These resins may also promote the adhesive strength of a coating and corrosion inhibition to metal surfaces of a coating.
Social implications
This will be used for the preparation of AB- and ABA-type block copolymers. These block copolymers may exhibit different properties due to incorporation of monomer into the block copolymer structure.
Originality/value
Novel Th-CFR comonomers were synthesised. These comonomers have higher glass transition temperature (Tg) and melting temperature (Tm) value than CFR alone. The chemical oxidation system has been used to polymerise these thiophene-functionalised ketonic resins.
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Nilgun Kizilcan and Merve Istif
The purpose of this paper is to produce an electroactive monomer containing ketonic resins and then to investigate redox reaction between Fe+3 and bounded thiophene in comonomers…
Abstract
Purpose
The purpose of this paper is to produce an electroactive monomer containing ketonic resins and then to investigate redox reaction between Fe+3 and bounded thiophene in comonomers. First, thiophene functionalised ketonic resins (Th-CFPDMSR) were synthesised by esterification reaction of thiophene-2-carbonyl chloride (ThCCl) and hydroxyl groups of cyclohexanone formaldehyde resin (CFR). Th-CFPDMSR was then polymerised by ferric salt. Thiophene modified ketonic resins (Th-CFPDMSR) as comonomers were characterised by common techniques such as gel permeation chromatography, proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimeter and scanning electron microscope.
Design/methodology/approach
Th-CFPDMSR comonomers were synthesised by esterification reaction of ThCCl and hydroxyl groups of ketonic resins. Then, the in-situ chemical oxidation (ISCO) of ThC-CFR in the presence of iron (III) chloride salt (FeCl3) was accomplished in chloroform/acetonitrile mixture solutions at room temperature.
Findings
Important structural factor determined quantitatively for Th-CFPDMSR is the CFPDMS/TCCl ratio after reaction. The mole ratio effect of TCCl and ketonic resin on the solubility, molecular weight, melting temperature (Tm) and glass transition temperature (Tg) values of the comonomers (TCCl-CFPDMSR) was investigated.
Research limitations/implications
The ferric ion (Fe+3) has a standard oxidation potential. Furthermore, FeCl3 can react with thiophene to produce a cation radical. FeCl3 cannot react with hydroxyl groups of ketonic resins. When ferric is used for ISCO application at relatively low temperatures (e.g. < 20°C), the oxidation reactions are usually less aggressive.
Practical implications
This work provides technical information for the synthesis of conducting block copolymer and for the synthesis of chain-extended resins. The modified resins contain thiophene. The chemical oxidation system has been used to polymerise these thiophene groups, and resins with much higher molecular weight might be produced. The resins may also promote the adhesive strength of a coating and corrosion inhibition to metal surfaces of a coating.
Originality/value
Novel Th-CFPDMSR comonomers were synthesised. These comonomers have higher Tg and Tm values than CF-PDMSR alone. The chemical oxidation system has been used to polymerise these thiophene functionalised ketonic resins.
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Nilgun Kızılcan and Selda Sert
Cyclohexanone-formaldehyde resin (CFR) was in situ modified with tannin (T) in the presence of sodium hydroxide. The purpose of this study is to produce eco-friendly…
Abstract
Purpose
Cyclohexanone-formaldehyde resin (CFR) was in situ modified with tannin (T) in the presence of sodium hydroxide. The purpose of this study is to produce eco-friendly tannin-modified cyclohexanone resins (TCFR) with a one-step method that has higher decomposition temperature than CFR. The solubility, molecular weight and thermal properties of the product were investigated.
Design/methodology/approach
Cyclohexanone, formalin (37 per cent aqueous solution) and tannin were mixed and 20 per cent aqueous NaOH solution was added to produce the resin. Tannin has environmentally friendly bio-based phenolic compounds that the tannin structure has been incorporated into the structure of the cyclohexanone formaldehyde resin during the in situ modification of resin, such as resole resin.
Findings
The improvement of the properties of the TCFRs produced from condensed tannin. TCFRs were soluble in common organic solvents. The product TCFR has a dark red colour.
Research limitations/implications
The reaction mixture must be stirred continuously. Subsequently, 37 per cent formalin was added drop-wise in total while refluxing. The amount of aqueous NaOH solution of it is limited, as the formed resin may become insoluble in common organic solvents. At the end of the reaction, a water-soluble resin is obtained. Then, the water of water phase was removed from TCFR reaction system, successively by evaporating with rotary evaporator.
Practical implications
This study provides the application of ketonic resins. The TCFR containing tannin groups may also promote the adhesive strength of a coating.
Social implications
These resins may be used for the preparation of adhesive. Condensed tannin, with a large amount of Catechol groups was considered for reducing the formaldehyde emission level on the adhesive system.
Originality/value
TCFR has been synthesised in the presence of a base catalyst. Environmental and ecological concerns have increased the attention paid by chemical industry to renewable raw materials.
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Keywords
Selda Sert and Nilgün Kızılcan
Cyclohexanone-formaldehyde resin (CFR) was in situ modified with olive pomace (OP) in the presence of sodium hydroxide. The purpose of this study is to produce eco-friendly OP…
Abstract
Purpose
Cyclohexanone-formaldehyde resin (CFR) was in situ modified with olive pomace (OP) in the presence of sodium hydroxide. The purpose of this study is to produce eco-friendly OP modified cyclohexanone composite resins (OPCFCR) with a one-step method that has higher condensation reaction temperature than CFR. The water absorption properties, gloss value and cross-cut adhesion properties of the product were investigated.
Design/methodology/approach
Cyclohexanone, formalin (37% aqueous solution) and tannin were mixed and 20% aqueous NaOH solution was added to produce the resin. OP has environmentally friendly bio-based lignin, cellulose and phenolic compounds and the OP structure has been incorporated into the structure of the CFR resin during the in situ modification, such as resole resin and polysaccharide. The weights of pomace were used as 5% and 10% of the weight of cyclohexanone in cyclohexanone-formaldehyde composite resins, respectively.
Findings
There is an improvement in the properties of the OPCFCR produced from an agricultural waste that is very abundant in Gulf of Edremit region of Balikesir. The OPCFCRs were soluble in common organic solvents. The product OPCFCR has a dark red-brown color.
Research limitations/implications
The reaction mixture must be stirred continuously. Subsequently, 37% formalin was added dropwise in total while refluxing. The amount of aqueous NaOH solution is limited as the formed resin may become insoluble in common organic solvents. At the end of the reaction, a water-insoluble resin is obtained.
Practical implications
This study provides the application of ketonic resins. The OPCFCR containing phenolic groups may also promote the adhesive strength of a coating.
Social implications
These resins may be used for the preparation of adhesive. OP, with a large amount of catechol groups, was considered for reducing the formaldehyde emission level on the adhesive system.
Originality/value
OPCFCR has been synthesized in the presence of a base catalyst. Environmental and ecological concerns have increased the attention paid by chemical industry to renewable raw materials.
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Keywords
The purpose of this paper was as follows. The in situ chemical oxidation (ICO) of vinyl aniline modified cyclohexanone formaldehyde resin (CFVAnR) in the presence of potassium…
Abstract
Purpose
The purpose of this paper was as follows. The in situ chemical oxidation (ICO) of vinyl aniline modified cyclohexanone formaldehyde resin (CFVAnR) in the presence of potassium persulphate salt (K2S2O8) was accomplished in dimethyl sulphoxide (DMSO) solutions at 35°C and 70°C. The chemical composition and structure of the oxidized CFVAnR were characterised by nuclear magnetic resonance (1H‐NMR) spectroscopy, Fourier transform infrared (FT‐IR) spectroscopy, DSC, TGA and SEM.
Design/methodology/approach
The reactive vinyl and amine groups of the cyclohexanone formaldehyde resin were reacted in the presence of potassium persulphate. CFVAn resin was dissolved in DMSO inside a round bottom flask immersed in a water bath thermostated at reaction temperature of 35°C and 70°C, respectively. Solution of K2S2O8 was prepared in DMSO and this was added into the resin solution.
Findings
It was shown that the vinyl groups in the resin were reacted easily with persulphate salt to obtain chain extended CFVAnR (CECFVAnR). The oxidised 4‐vinyl aniline modified cyclohexanone‐formaldehyde resin has solublity in organic solvents.
Research limitations/implications
The reaction mixture must be stirred continuously. Temperature should be controlled to prevent the thermal polymerisation of vinyl group and higher branching of amino groups. The persulphate ion (S2O82−) has a standard oxidation potential, but when activated by heat (40‐60°C). Furthermore, sulphate radical can react with water or hydroxide to produce hydroxyl radical (−OH). When persulphate is used for in situ chemical oxidation (ISCO) application at relatively low temperatures (e.g. <20°C), the oxidation reactions are usually less aggressive due to a slow generation rate of SO4−.
Practical implications
This study provides technical information for the synthesis of chain extended resins. The modified resins contain vinyl groups. The chemical radical system has been used to polymerise these vinyl groups and resins with much higher molecular weight might be produced. The resins may also promote the adhesive strength of a coating and corrosion inhibition to metal surfaces of a coating.
Social implications
This resin will be used for the preparation of AB‐ and ABA‐type block copolymers. These block copolymers may exhibit different properties due to incorporation of ketonic resins into the block copolymer structure.
Originality/value
Chain extended CFVAnR (CECFVAnR) was synthesised by one step reduction‐oxidation reaction, at 35°C (CECFVAnR1) and 70°C (CECFVAnR2) in the presence of potassium persulphate salt. These soluble resins may overcome difficulties in the applications of polymers and open new application areas. Therefore, the chain extended vinyl aniline modified resin may find a number of new application areas as well as existing UV curable resin and polymer applications.
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Ümran Burcu Alkan, Nilgün Kızılcan and Başak Bengü
The purpose of this study is the development of sustainable and low-formaldehyde emission wood adhesive formulations.
Abstract
Purpose
The purpose of this study is the development of sustainable and low-formaldehyde emission wood adhesive formulations.
Design/methodology/approach
Three-step urea formaldehyde (UF) resin has been in situ modified with calcium lignosulfonate (LS) and/or 1,4 butanediol diglycidyl ether (GE). The structural, chemical, thermal and morphological characterizations were carried out on resin samples. These resins have been applied for particleboard pressing, and UF, UF-LS and UF-GE were evaluated as P2 classes according to EN 312.
Findings
The results show that the improved LS- or diglycidyl ether-modified UF wood adhesives were successful in their adhesive capacity, and the formaldehyde content of the final product was obtained as low as 8 mg/100 g. This paper highlights that the presented adhesive formulations could be a potential eco-friendly and cost-effective alternative to formaldehyde-based wood adhesives for interior particleboard production.
Research limitations/implications
Combination of LS and GE resulted in weaker mechanical properties and fulfilled P1 class particleboards due to temperature and duration conditions. Therefore, in situ usage of LS or GE in UF resins is highly recommended for particleboard pressing. Formaldehyde content of particleboards was determined with the perforator method according to EN 12460-5 and all of the particleboards exhibited E1 class. LS was more efficient in decreasing formaldehyde content than GE.
Practical implications
This study provides the application of particleboards with low formaldehyde emission.
Social implications
The developed LS- and diglycidyl ether-modified UF resins made it possible to obtain boards with significantly low formaldehyde content compared with commercial resins.
Originality/value
The developed formaldehyde-based resin formulation made it possible to produce laboratory-scale board prototypes using LS or GE without sacrificing of press factors and panel quality.
Details
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Salise Oktay, Nilgün Kızılcan and Başak Bengü
In industrial applications, formaldehyde-based wood adhesives have been used extensively because of their low costs and high reactivity. However, their real-world applications are…
Abstract
Purpose
In industrial applications, formaldehyde-based wood adhesives have been used extensively because of their low costs and high reactivity. However, their real-world applications are hindered by some main bottlenecks, especially the formaldehyde emission and usage of nonrenewable raw materials. The purpose of this study is the development of sustainable and formaldehyde-free wood adhesive formulation.
Design/methodology/approach
In this study, starch and tannin-based wood adhesive were synthesized. Chemical structures and thermal properties of the prepared bio-based resin formulations were elucidated by using Fourier transform infrared and differential scanning calorimetry analysis, respectively. Laboratory scale particleboard production was carried out to determine the performance of the developed resin formulations. Obtained results were evaluated in dry medium (P2) according to European norms EN 312 (2010). Furthermore, the board formaldehyde content was determined by using the perforator method according to the European Norm EN 12460-5.
Findings
The results show that the improved starch and tannin-based wood adhesives were successful in their adhesive capacity, and the formaldehyde content of the final product was obtained as low as 0.75 mg/100 g. This paper highlights that the presented adhesive formulations could be a potential eco-friendly and cost-effective alternative to the formaldehyde-based wood adhesives for interior particleboard production.
Research limitations/implications
Starch-based resins in the liquid form needed to be continuously mixed throughout their shelf life to prevent the starch from settling because it was not possible to dissolve the precipitated starch again after a while. For this reason, starch was given to the chips in powder form while preparing the particleboard.
Practical implications
In conclusion, this study shows that the developed bio-based resin formulations have a high potential to be used for producing interior-grade particleboards instead of commercial formaldehyde-based wood adhesives because the obtained results generally satisfied the interior grade particleboard requirements according to European norms EN 312, P2 class (2010). In addition, it was determined that the produced boards had significantly low formaldehyde content. The low formaldehyde content of the final boards was not because of the resin but because of the natural structure of the wood raw material, press parameters and environmental factors.
Social implications
The developed bio-based resin system made it possible to obtain boards with significantly low formaldehyde content compared to commercial resins.
Originality/value
The developed bio-based resin formulation made it possible to produce laboratory-scale board prototypes at lower press factors and board densities compared to their counterparts.
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Belkis Ustamehmetoğlu, Ahmet Akar, Nilgun Kizilcan and Eda Kelleboz
The purpose of this paper is to develop the soluble and processable conducting copolymers of carbazole (Cz), ethylcarbazole (ECz), N‐vinylcarbazole (NVCz) by oxidatively…
Abstract
Purpose
The purpose of this paper is to develop the soluble and processable conducting copolymers of carbazole (Cz), ethylcarbazole (ECz), N‐vinylcarbazole (NVCz) by oxidatively polymerising carbazoles by ceric ammonium nitrate (CAN) in the presence of methyl ethyl ketone formaldehyde resin (MEKF‐R); and to report the advantages of obtaining copolymer structure.
Design/methodology/approach
A new class of soluble and conductive P(Cz/MEKF‐R), P(NVCz/MEKF‐R) and P(ECz/MEKF‐R) copolymers were synthesised by the method of oxidative polymerisation with ceric ammonium nitrate. MEKF‐R, CAN and carbazole monomers (Cz, NVCz and ECz) were dissolved in acetonitrile separately. Then, the CAN solution was added dropwise into the mixture of MEKF‐R and Cz, NVCz or ECz solutions while stirring and a green powder was formed almost instantaneously. After one hour stirring at 25°C, the powder was filtered, washed with acetonitrile and dried at room temperature. A green coloured product was obtained. The colourless insulator copolymer present in this product was separated by selectively dissolving with toluene. The insoluble green copolymer was filtered off and dried at room temperature under vacuum. The products were characterised by FTIR, DSC thermograms, 1H‐NMR, four‐point probe conductivity and atomic absorption measurements.
Findings
The solubility and conductivity of the Cz/MEKF‐R copolymer P(Cz/MEKF‐R), the NVCz/MEKF‐R copolymer P(NVCz/MEKF‐R) and the ECz/MEKF‐R copolymer P(ECz/MEKF‐R) were regulated by the ratios of (Cz, NVCz, ECz)/CAN/MEKF‐R. By inclusion of the ketonic resin segments to the polycarbazole chains, thermally processable copolymers have been obtained with a melting point of about 80°C. FT‐IR results in different reaction time and the presence of metal in copolymers show together a complex between monomer‐metal and resin.
Research limitations/implications
This study focuses on obtaining conductive, soluble and processable copolymers. Since the ketonic resin is an insulator, in order to obtain both conductive and totally soluble polymer, successively regulating the ratios of (Cz, NVCz, ECz)/CAN/MEKF‐R is necessary.
Practical implications
This work provides technical information for the synthesis of conducting and totally soluble copolymer.
Originality/value
The conductive P(Cz/MEKF‐R), P(NVCz/MEKF‐R) and P(ECz/MEKF‐R) copolymers obtained by the method of oxidative polymerisation with ceric ammonium nitrate, which are totally soluble in DMF, could only be produced with this method and may increase the area of application of the carbazole polymers.