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Topical Collection "Polymeric Adhesives"

Editor

Collection Editor
Prof. Dr. Antonio Pizzi

LERMAB, Laboratoire d’Etude et de Recherche sur le MAteriau Bois, Université de Lorraine, 27 rue Philippe Seguin, CS60036, 88021 Epinal, France
Website | E-Mail
Phone: (+33) 623126940
Interests: polycondensation; resins; adhesives; thermosetting polymers for adhesives; natural polymers for industrial use; fibrous and wood composites; polymeric wood constituents (cellulose, lignin, tannins)

Topical Collection Information

Dear Colleagues,

Today’s intense search for adhesives of superior performance and lower cost, but based on novel approaches, is evident in both the fields of synthetic polymeric adhesives, as well as for adhesives from renewable polymeric materials. This Topical Collection is aimed at collecting cutting-edge original research papers and reviews on the main areas where novel approaches, conceptual or applied, are taken to the fundamental chemistry, mechanisms, applications and technologies of polyurethanes, epoxies, acrylics and many other synthetic adhesives be it oil-derived, coal-derived, inorganic binders or moreover biosourced polymeric adhesives from renewable materials. Mixed synthetic/biosourced adhesives are also aimed at as a particularly lively field of interest. The Collection is aimed at collecting cutting-edge research on all adhesive types under development throughout the vast variety of adhesives in use today, from acrylics to epoxies, to polyurethanes and isocyanates, phenolics and aminoplastics and many others.

Both original contributions and reviews are welcome. The first-round deadline for submitting papers is 30 October 2017.

Prof. Dr. Antonio Pizzi
Collection Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the collection website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Synthetic adhesives
  • Biosourced adhesives
  • Mixed Synthetic/biosourced adhesives
  • Adhesion, synthesis and cross-linking mechanisms
  • Novel concepts in adhesion and adhesives
  • Novel or improved adhesive technologies
  • Adhesives application technologies
  • Polyurethane and isocyanate adhesives
  • Acrylic adhesives
  • Epoxy adhesives
  • Phenolic adhesives
  • Aminoplastic adhesives
  • Furanic adhesives
  • Polyvinyl and EVA adhesives
  • Unsaturated polyester adhesives
  • Hot-melt adhesives
  • Anaerobic and aerobic adhesives
  • Cyanoacrylate adhesives
  • Silicone adhesives and sealants
  • Pressure sensitive adhesives
  • Electrically conducting adhesives
  • Rubber adhesives
  • Protein adhesives

Related Special Issue

Published Papers (11 papers)

2017

Open AccessCommunication Synthesis of Humin-Phenol-Formaldehyde Adhesive
Polymers 2017, 9(8), 373; doi:10.3390/polym9080373 (registering DOI)
Received: 27 May 2017 / Revised: 11 August 2017 / Accepted: 14 August 2017 / Published: 18 August 2017
PDF Full-text (2289 KB) | HTML Full-text | XML Full-text
Abstract
Humins are low-value-added byproducts from the biomass acid hydrolysis process. In the present work, humins were first employed as a phenol replacement for synthesis of modified phenol-formaldehyde adhesives through a two-step process. In this process, humins were first utilized to obtain alkaline soluble
[...] Read more.
Humins are low-value-added byproducts from the biomass acid hydrolysis process. In the present work, humins were first employed as a phenol replacement for synthesis of modified phenol-formaldehyde adhesives through a two-step process. In this process, humins were first utilized to obtain alkaline soluble products, mainly consisting of phenolics, through a hydrothermal process. The obtained alkaline soluble products then reacted with phenol and formaldehyde to produce humin-phenol-formaldehyde adhesive (HPFA). The physicochemical properties of HPFA, including viscosity, bonding strength, pH, free formaldehyde level, free phenol level and solid content, met the requirements of the GB/T 14732-2006 Chinese National Standard. Full article
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Open AccessArticle Theoretical Study on Decomposition Mechanism of Insulating Epoxy Resin Cured by Anhydride
Polymers 2017, 9(8), 341; doi:10.3390/polym9080341
Received: 11 July 2017 / Revised: 31 July 2017 / Accepted: 3 August 2017 / Published: 4 August 2017
PDF Full-text (3267 KB) | HTML Full-text | XML Full-text
Abstract
High temperatures caused by partial discharge results in the decomposition of insulating epoxy resins in electrical equipment. In this paper, the ReaxFF force field is used to investigate the decomposition process of epoxy resins cured by anhydride and the formation mechanisms of small-molecule
[...] Read more.
High temperatures caused by partial discharge results in the decomposition of insulating epoxy resins in electrical equipment. In this paper, the ReaxFF force field is used to investigate the decomposition process of epoxy resins cured by anhydride and the formation mechanisms of small-molecule gases. Results show that the initiation reaction is the cleavage of an ester bond linked with an epoxy resin. Produced by the decomposition of ester groups, CO2 is the first and most abundant product. Meanwhile, CH2O can be generated through three main ways, although the process still depends on the decomposition of epoxy functional groups. H2O is produced by free radical collision and dehydration. The production of small-molecule gases has the following sequence: CO2, CH2O, CO, and H2O. The produced gases have the following order according to amount: CO2, CH2O, H2O, and CO. Full article
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Open AccessArticle Improve Performance of Soy Flour-Based Adhesive with a Lignin-Based Resin
Polymers 2017, 9(7), 261; doi:10.3390/polym9070261
Received: 10 May 2017 / Revised: 26 June 2017 / Accepted: 27 June 2017 / Published: 3 July 2017
PDF Full-text (1773 KB) | HTML Full-text | XML Full-text
Abstract
A lignin-based resin (LB) was used to improve the performance of soy flour-based adhesives. Soy flour (SF), polyamidoamine-epichlorohydrin (PAE), and LB were used to develop a plywood adhesive. The solid content and viscosity of the adhesive, the functional groups, the thermo-stability, and the
[...] Read more.
A lignin-based resin (LB) was used to improve the performance of soy flour-based adhesives. Soy flour (SF), polyamidoamine-epichlorohydrin (PAE), and LB were used to develop a plywood adhesive. The solid content and viscosity of the adhesive, the functional groups, the thermo-stability, and the crystallinity of the cured adhesives were characterized, and the performance of the resultant adhesive was evaluated by fabricating three-ply plywood. Results showed that the LB and PAE mixture used to modify the SF adhesive improved both dry and wet bond strength by 66.3% and 184.2%, respectively. Therefore, the PAE improved the wet bond strength, and the LB improved the dry bond strength. The improvement was attributed to: (1) the reaction of LB/PAE with the functions of the soy protein to form a cross-linking network; (2) a polycondensation reaction between the LB molecules improved the crosslinking density of the adhesive to form an interpenetration structure with cross-linked proteins; and (3) the easy penetration of the LB into the wood surface that enhanced interlocking between the wood and adhesive. Furthermore, the denser structure created by the LB and the PAE mixture improved thermal stability and decreased the crystallinity of the cured adhesive. The use of the LB and the PAE mixture increased the solid content by 35.5%, while still making its viscosity acceptable for industrial applications. Full article
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Open AccessArticle Controlled Light Cross-Linking Technique to Prepare Healable Materials
Polymers 2017, 9(6), 241; doi:10.3390/polym9060241
Received: 25 April 2017 / Revised: 19 June 2017 / Accepted: 19 June 2017 / Published: 21 June 2017
PDF Full-text (7825 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Detection of defects, damages and cracks in structural polymers is very difficult, and even if they are detected, they will be very hard to be repaired. This is because different kinds of stress can reduce the mechanical efficiency of structural and functional thermosetting
[...] Read more.
Detection of defects, damages and cracks in structural polymers is very difficult, and even if they are detected, they will be very hard to be repaired. This is because different kinds of stress can reduce the mechanical efficiency of structural and functional thermosetting composite materials and they can damage the polymer matrix, thus reducing the purposed properties. General healing processes use thermal energy “alone” to heal these materials, thus impairing the intended properties of the materials. Therefore, we present a thermal healing ability that can be switched-on and/or -off at desire using illumination by photon energy (visible and ultra violet). By this technique, one can control local heal while keeping the efficiency of the material nearly unchanged. Furan-based cross-linker chemically reacts (forward- and reverse-reaction) with short-chains of maleimide-substituted poly(lauryl methacrylate) to form robust chemical bonds. This permits us to perform local control over thermally induced de- and/or re-cross-linking techniques. One can extend and apply this technique to cover micro-devices, coating-techniques, fine lithography, micro- and nano-fabrication processes, etc. Therefore, the present work developed a suitable technology with structural polymeric material, which has the ability to self-heal cracks (and damages) and recover structural function. Full article
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Open AccessArticle The Preparation and Characterization of Pyrolysis Bio-Oil-Resorcinol-Aldehyde Resin Cold-Set Adhesives for Wood Construction
Polymers 2017, 9(6), 232; doi:10.3390/polym9060232
Received: 28 April 2017 / Revised: 14 June 2017 / Accepted: 15 June 2017 / Published: 18 June 2017
PDF Full-text (3392 KB) | HTML Full-text | XML Full-text
Abstract
Resorcinol-formaldehyde (RF) resin is a kind of excellent exterior-grade wood structural adhesive, which can be conveniently cold-set for various applications. In order to decrease the production cost, pyrolysis bio-oil from renewable bioresources was used to replace resorcinol to synthesize the bio-oil-resorcinol-aldehyde (BRF) resin.
[...] Read more.
Resorcinol-formaldehyde (RF) resin is a kind of excellent exterior-grade wood structural adhesive, which can be conveniently cold-set for various applications. In order to decrease the production cost, pyrolysis bio-oil from renewable bioresources was used to replace resorcinol to synthesize the bio-oil-resorcinol-aldehyde (BRF) resin. The effect of replacing resorcinol with bio-oil on the properties, bonding performance, and characterization of resorcinol-aldehyde resin was comparatively investigated. A higher solid content and viscosity, albeit a lower shear strength, was found when the replacement ratio of bio-oil increased. The bonding performance of BRF with 10 and 20 wt % bio-oil was close to that of the pure RF resin. However, the trends of being less cross-linked, more easily decomposed, but more porous were found when the substitution ratio of bio-oil was higher than 20 wt %. Interestingly, it was found that the wood failure values of the BRF resins with bio-oil of no more than 20 wt % were slightly higher than that of the pure RF resin. On the whole, BRF resins with 20 wt % bio-oil is recommended as a wood structural adhesive, comprehensively considering the bio-oil substitution ratio and resin properties. The results obtained here showed that pyrolysis bio-oil is a promising green raw material for the production of RF resin with lower cost. Full article
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Open AccessArticle Analysis of the Cross-Linking Reaction of Lignin with Triethyl Phosphate by MALDI-TOF and 13C NMR
Polymers 2017, 9(6), 206; doi:10.3390/polym9060206
Received: 4 April 2017 / Revised: 31 May 2017 / Accepted: 2 June 2017 / Published: 4 June 2017
PDF Full-text (4649 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The reaction of condensation and cross-linking of desulfurized kraft lignin with triethyl phosphate (TEP) was explored. Catechol, a simple model of the aromatic ring of lignin, and glycerol, a model compound of the aliphatic hydroyl groups of the side chain of lignin, were
[...] Read more.
The reaction of condensation and cross-linking of desulfurized kraft lignin with triethyl phosphate (TEP) was explored. Catechol, a simple model of the aromatic ring of lignin, and glycerol, a model compound of the aliphatic hydroyl groups of the side chain of lignin, were employed under similar reaction conditions. Solid state cross-polarisation/magic-angle spinning (CP-MAS) 13C NMR and matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) spectroscopy studies showed that polycondensation occurs on phenolic hydroxyl groups of lignin, as well as on aliphatic hydroxyls groups of its side chain. The reactions appear to be favoured by higher temperatures and in the presence of ammonia. Preliminary adhesion tests on wood shown good hydrophobicity properties of the surface treated with lignin-TEP-based resin. Initial application tests carried out at high temperature demonstrated as good performance as metallic coating. Full article
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Open AccessArticle New Mechanism Proposed for the Base-Catalyzed Urea–Formaldehyde Condensation Reactions: A Theoretical Study
Polymers 2017, 9(6), 203; doi:10.3390/polym9060203
Received: 12 May 2017 / Revised: 27 May 2017 / Accepted: 27 May 2017 / Published: 2 June 2017
PDF Full-text (1711 KB) | HTML Full-text | XML Full-text
Abstract
Base-catalyzed urea–formaldehyde condensation reactions were investigated by using a quantum chemistry method. It was found that monomethylolurea or N,N’-dimethylolurea can produce the methyleneurea intermediate (–HN–CO–N=CH2) with the catalysis of base. The E1cb (unimolecular elimination of conjugate base) mechanism
[...] Read more.
Base-catalyzed urea–formaldehyde condensation reactions were investigated by using a quantum chemistry method. It was found that monomethylolurea or N,N’-dimethylolurea can produce the methyleneurea intermediate (–HN–CO–N=CH2) with the catalysis of base. The E1cb (unimolecular elimination of conjugate base) mechanism was identified for the formation of such an intermediate. The potential energy barrier was theoretically predicted to be 59.6 kJ/mol for the E1cb step, which is about half of that of previously proposed SN2 (bimolecular nucleophilic substitution) mechanism. In the subsequentcondensation reactions, Michael addition reactions that lead to different condensed structures can occur between the methyleneurea intermediate and the anions produced from methylolureas under alkaline conditions. Based on the theoretical calculations on the kinetics and thermodynamics of the selected reactions, the competitive formations of methylene linkages, ether linkages and uron were discussed in combination with our previous experimental observations. Full article
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Open AccessArticle Investigation on the Influence of Chain Extenders on the Performance of One-Component Moisture-Curable Polyurethane Adhesives
Polymers 2017, 9(5), 184; doi:10.3390/polym9050184
Received: 2 April 2017 / Revised: 15 May 2017 / Accepted: 16 May 2017 / Published: 21 May 2017
PDF Full-text (3590 KB) | HTML Full-text | XML Full-text
Abstract
In this work, a number of chain extended moisture-curable urethane prepolymers were synthesized in order to develop isocyanate terminated urethane prepolymer formulations that would simultaneously display both high adhesive strength and low viscosity. Proton nuclear magnetic resonance spectroscopy (1H-NMR), size exclusion
[...] Read more.
In this work, a number of chain extended moisture-curable urethane prepolymers were synthesized in order to develop isocyanate terminated urethane prepolymer formulations that would simultaneously display both high adhesive strength and low viscosity. Proton nuclear magnetic resonance spectroscopy (1H-NMR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and Brookfield viscometry were utilized for characterizing the prepared urethane prepolymers. In addition, the adhesion strength of the cured prepolymers was determined by tensile shear strength test according to the DIN EN (Deutsches Institut für Normung, the German Institute for Standardization) 1465 standard. Especially, the role of different types of linear (butanediol, pentanediol) and branched chain extenders (dipropyleneglycol (di-PPG), tripropyleneglycol (tri-PPG) and the influence of their dosage on the degree of microphase separation between hard segments (HS) and soft segments (SS) in urethane prepolymers were studied. Furthermore, the benefits of utilizing either a one-step versus a two-step polymerization process were investigated. The results revealed that the extent of phase separation of different urethane prepolymers was dependent on the extent of hydrogen bonding interactions which was extensively studied by attenuated total reflectance infrared spectroscopy (ATR-FTIR). The incorporation of branched chain extenders (di-PPG and tri-PPG) did not result in notable phase separation between hard segments and soft segments, while linear chain extenders (pentanediol and butanediol) readily promoted phase separation. The degree of phase separation was particularly pronounced for butanediol, and when the linear chain extender ratio was higher than or equal to 0.74. Compared with a two-stage process, one-stage process produced more randomly distributed polymer chains with highly dispersed hard segments. Thus, urethane prepolymers exhibiting strong adhesive strength with simultaneously low viscosity were successfully developed by systematic adjustment of structural parameters. Full article
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Open AccessArticle Soy-Based Adhesive Cross-Linked by Phenol-Formaldehyde-Glutaraldehyde
Polymers 2017, 9(5), 169; doi:10.3390/polym9050169
Received: 10 March 2017 / Revised: 2 May 2017 / Accepted: 5 May 2017 / Published: 8 May 2017
PDF Full-text (1058 KB) | HTML Full-text | XML Full-text
Abstract
To prepare a low-formaldehyde soy-based adhesive with good water resistance, phenol-formaldehyde modified with glutaraldehyde (PFG) with lower free phenol and free formaldehyde contents was used to cross-link the soy-based adhesive. The results showed that the mechanical properties and water resistance of plywood prepared
[...] Read more.
To prepare a low-formaldehyde soy-based adhesive with good water resistance, phenol-formaldehyde modified with glutaraldehyde (PFG) with lower free phenol and free formaldehyde contents was used to cross-link the soy-based adhesive. The results showed that the mechanical properties and water resistance of plywood prepared with soy-based adhesive with PFG was better than that of plywood with the same amount of phenol-formaldehyde (PF). The reaction between phenol and glutaraldehyde was proved by 13C-NMR. Under the optimized preparation conditions for plywood, that is to say, press temperature 160 °C, press time 4 min and resin loading 320 g·m−2, type I plywood could be prepared with 9% PFG as a cross-linker of soy-based adhesive. The Differential Scanning Calorimetry (DSC) result confirmed the cross-linking reaction between soy-based adhesive and PFG or PF. The activation energy of soy-based adhesive with cross-linker PFG was higher than that with PF resin. Full article
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Open AccessArticle Preparation, Characterization and Mechanical Properties of Bio-Based Polyurethane Adhesives from Isocyanate-Functionalized Cellulose Acetate and Castor Oil for Bonding Wood
Polymers 2017, 9(4), 132; doi:10.3390/polym9040132
Received: 6 March 2017 / Revised: 29 March 2017 / Accepted: 3 April 2017 / Published: 5 April 2017
PDF Full-text (1617 KB) | HTML Full-text | XML Full-text
Abstract
Nowadays, different types of natural carbohydrates such as sugars, starch, cellulose and their derivatives are widely used as renewable raw materials. Vegetable oils are also considered as promising raw materials to be used in the synthesis of high quality products in different applications,
[...] Read more.
Nowadays, different types of natural carbohydrates such as sugars, starch, cellulose and their derivatives are widely used as renewable raw materials. Vegetable oils are also considered as promising raw materials to be used in the synthesis of high quality products in different applications, including in the adhesive field. According to this, several bio-based formulations with adhesion properties were synthesized first by inducing the functionalization of cellulose acetate with 1,6-hexamethylene diisocyanate and then mixing the resulting biopolymer with a variable amount of castor oil, from 20% to 70% (wt). These bio-based adhesives were mechanically characterized by means of small-amplitude oscillatory torsion measurements, at different temperatures, and standardized tests to evaluate tension loading (ASTM-D906) and peel strength (ASTM-D903). In addition, thermal properties and stability of the synthesized bio-polyurethane formulations were also analyzed through differential scanning calorimetry and thermal gravimetric analysis. As a result, the performance of these bio-polyurethane products as wood adhesives were compared and analyzed. Bio-polyurethane formulations exhibited a simple thermo-rheological behavior below a critical temperature of around 80–100 °C depending on the castor oil/cellulose acetate weight ratio. Formulation with medium castor oil/biopolymer weight ratio (50:50 % wt) showed the most suitable mechanical properties and adhesion performance for bonding wood. Full article
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Open AccessArticle The Influence of pH on the Melamine-Dimethylurea-Formaldehyde Co-Condensations: A Quantitative 13C-NMR Study
Polymers 2017, 9(3), 109; doi:10.3390/polym9030109
Received: 22 February 2017 / Revised: 13 March 2017 / Accepted: 15 March 2017 / Published: 17 March 2017
Cited by 1 | PDF Full-text (1800 KB) | HTML Full-text | XML Full-text
Abstract
1,3-dimethylurea (DMU) was used to mimic urea and to model melamine-urea-formaldehyde (MUF) co-condensation reactions. The products of 1,3-dimethylurea-formaldehyde (DMUF), melamine-formaldehyde (MF), and melamine-1,3-dimethylurea-formaldehyde (MDMUF) reactions under alkaline and weak acidic conditions were compared by performing quantitative carbon-13 nuclear magnetic resonance (13C-NMR)
[...] Read more.
1,3-dimethylurea (DMU) was used to mimic urea and to model melamine-urea-formaldehyde (MUF) co-condensation reactions. The products of 1,3-dimethylurea-formaldehyde (DMUF), melamine-formaldehyde (MF), and melamine-1,3-dimethylurea-formaldehyde (MDMUF) reactions under alkaline and weak acidic conditions were compared by performing quantitative carbon-13 nuclear magnetic resonance (13C-NMR) analysis. The effect of pH on the co-condensation reactions was clarified. With the presence of the methyl groups in DMU, the appearance or absence of the featured signal at 54–55 ppm can be used to identify the co-condensed methylene linkage –N(–CH3) –CH2–NH–. Under alkaline condition, MDMUF reactions produced primarily MF polymers and the featured signal at 54–55 ppm was absent. Even though the co-condensations concurrently occurred, undistinguishable and very minor condensed structures with ether linkage were formed. Differently, under weak acidic condition, the relative content of co-condensed methylene carbons accounts for over 40%, indicating the MDMUF co-condensation reactions were much more competitive than the self-condensations. The formation of reactive carbocation intermediate was proposed to rationalize the results. Full article
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