MF Resin Research Articles

Organic solvents-free and ambient-pressure drying melamine formaldehyde resin aerogels with homogeneous structures, outstanding mechanical strength and flame retardancy

Atmospheric drying method for fabricating aerogels is considered the most promising way for casting aerogels on a large scale. However, the organic solvent exchange, remaining environmental pollution risk, is a crucial step in mitigating the impact of surface tension during the atmospheric drying process, especially for wet gel formed through the alkoxy-derived sol-gel process, such as melamine-formaldehyde resin (MF) aerogel. Herein, a tough polymer-assisted in situ polymerization was proposed to fabricate MF resin aerogel with a combination of mechanical toughness and strength, enabling it to withstand the capillary force during water evaporation. The monolithic MF resin aerogel through the sol-gel method can be directly prepared without additional network strengthening or organic solvent exchange. The resulting MF resin aerogel exhibits a homogeneous as well as hierarchical structure with macropores and mesopores (~6 μm and ~5 nm), high compressive modulus of 31.8 MPa, self-extinguishing property, and high-temperature thermal insulation with 97 % heat decrease for butane flame combustion. This work presents a straightforward and environmentally friendly method for fabricating MF resin aerogels with nanostructures and excellent performance in open conditions, exhibiting various applications.

Microencapsulated phase change material through cellulose nanofibrils stabilized Pickering emulsion templating

Phase change materials (PCMs) possess remarkable capability to store and release substantial amounts of energy during the processes of melting and crystallization across a wide temperature range, thus holding great promise in applications related to temperature regulation and thermal energy storage. Herein, to effectively address PCM leakage and enhance thermal conduction, PCM microcapsules with melamine–formaldehyde resin (MF) shell were prepared using in situ polymerization of Pickering emulsions stabilized by cellulose nanofibrils (CNFs). CNFs were selected as the stabilizers for the Pickering emulsions and as reinforcing nanofillers for the MF shell, owing to their excellent emulsifying capability, high mechanical strength, and sustainable nature. Paraffin wax (PW) was utilized as the PCM material. The resulting PCM microcapsules with MF resin shells and PW core had a diameter ranging from 2 to 4 µm. Results showed that microcapsule with the core–shell ratio of 2 (Micro-2.0) exhibited the highest latent heat of crystallization and latent heat of fusion, measuring approximately 128.40 J/g and 120.23 J/g, respectively. The encapsulation efficiency of Micro-2.0 was determined to be approximately 79.84%.

Waterborne etherified MF and PVAc hybrid resin containing nanoclay as intumescent flame-retardant plywood coatings

Waterborne etherified MF and PVAc hybrid resin containing nanoclay as intumescent flame-retardant plywood coatings

Multi‐Unit Needleless Electrospinning for One‐Step Construction of 3D Waterproof MF‐PVA Nanofibrous Membranes as High‐Performance Air Filters

The airborne particulate matter (PM) seriously threatens people's health. Personal protective equipment with electrospun nanofibers is an effective method to make people away from air pollutants. Herein, 3D waterproof melamine-formaldehyde polyvinyl alcohol (MF-PVA) nanofibrous membranes are fabricated by a one-step method combining multi-unit needleless electrospinning and a thermal treatment device in a line. 3D nanofibrous structures can be controlled by adjusting the solution concentration of each unit. The PVA nanofibrous membranes become waterproof after cross-linking with MF resin in the following thermal treatment device. The optimized MF-PVA nanofibrous membrane shows excellent air filtration performance (97.3% for PM0.3 , 100% for PM1.0 , and 100% for PM2.5 ) and low air resistance (76Pa). These 3D waterproof MF-PVA nanofibrous membranes exhibit ultra-stable performance in various practical environments.

Studies on laminated and scrimber composites produced from thermally modified D. strictus bamboo bonded with melamine-based adhesive

Bamboo culms of Dendrocalamus strictus (Roxb.) were subjected to thermal modification at different treatment temperatures of 160, 180 and 200 °C under partial vacuum. Control and thermally modified bamboos were converted into strips and crushed strands to produce laminated (LBL) and scrimber (SBL) composites respectively using melamine formaldehyde adhesive. Effects of treatment temperatures on various properties including decay resistance were studied and characterized using XRD and FTIR. Average EMC was reduced to different levels depending on severity of thermal treatments. Density of composite was improved significantly and increasing treatment temperatures exhibited greater anti-swelling efficiency. Dark colour of modified bamboo was influenced by treatment parameters, while microstructure was not much affected. Most of mechanical parameters of composites produced from bamboo modified were enhanced. However, higher temperature (≥ 200 °C) showed detrimental effects on strength. Modified bamboo exhibited greater decay resistance against two rotting fungi. Some changes in crystalline structure and certain functional groups were observed after thermal modification. With desirable improvements in aesthetic and quality parameters, composites from thermally modified bamboo may be considered as ecological alternative to preservative treated materials. The LBL and SBL may, therefore, be utilized in production of valued-added lifestyle artifact in allied bamboo industry sectors. • Laminated and scrimber composites prepared from thermally modified bamboo and MF resin. • Density, ASE and decay resistance of composites were significantly improved. • Bamboo composites exhibited significant variations in different mechanical properties. • Composites from thermally modified bamboo found suitable for structural applications.

Flexible phase change composite films with improved thermal conductivity and superb thermal reliability for electronic chip thermal management

High-performance flexible composites with excellent thermal management ability are essential to dissipate the heat generated in electronic systems. Herein, micro-encapsulated phase change material (MPCM) with n-Docosane core and MF resin shell is prepared. The obtained MPCM exhibits large phase change enthalpy (192.9 J/g). Subsequently, flexible composites are prepared by incorporating the MPCM, multi-walled carbon nanotubes (MWCNT) and hexagonal boron nitride (h-BN) in styrene-ethylene-propylene-styrene (SEPS) polymer matrix. At 30 wt% MPCM, the phase change enthalpy of 60.6 J/g is achieved. 3 wt%MWCNT/10 wt%h-BN/30 wt%MPCM composites show improved thermal conductivity of 0.44 W m−1 K−1, which is 95.5 % higher than pure SEPS. The composites are applied in chip for thermal energy dissipation, the temperature of chip’s lower surface is only 62.6 °C, which is 22.84 % lower than pure SEPS. Overall, the MWCNT/h-BN/MPCM composites with superior thermal properties and mechanical characteristics are promising in the field of electronic equipment thermal dissipation.

Multivariate Curve Resolution (MCR) of real-time infrared spectra for analyzing the curing behavior of solid MF thermosetting resin

The isothermal curing of melamine resin is investigated by in-line infrared spectroscopy at different temperatures. The infrared spectra are decomposed into time courses of characteristic spectral patterns using Multivariate Curve Resolution (MCR). It was found that depending on the applied curing temperature, melamine films with different spectral fingerprints and correspondingly different chemical network structures are formed. The network structures of fully cured resin films are specific for the applied curing temperatures used and cannot simply be compensated by changes in the curing time. For industrial curing processes, this means that cure temperature is the main system determining factor at constant M:F ratio. However, different MF resin networks can be specifically obtained from one and the same melamine resin by suitable selection of the curing time and temperatures profiles to design resin functionality. The spectral fingerprints after short curing time as well as after long curing time reflect the fundamental differences in the thermoset networks that can be obtained with industrial short-cycle and multi-daylight presses.

The hydrolytic stability and structure of the cured melamine-urea-formaldehyde resin

ABSTRACT The hydrolysis of cured melamine-urea-formaldehyde (MUF) resin leads to the increment of formaldehyde emission of the MUF resin-bond wood boards. To learn the influencing factors on the hydrolytic stability of cure MUF resin, a variety of amino resins (UF resin, MF resin, MUF resin) were synthesized in the laboratory. The amount of formaldehyde liberated and mass loss of cured amino resins were attained after acidic hydrolysis. The branched structure of cured MUF resins with different melamine levels added at different addition stages was characterized by the XRD technology. The relationship between the hydrolytic stability and branched structure of cured MUF resin was disclosed. The TG and DSC curves of MUF and UF resins were obtained by the differential scanning calorimetry (DSC) at the normal pressure. Their DTG curves were obtained by taking the first derivative of TG curves. The DTG curve shows the variation of the mass-loss rate of UF resin and MUF resin with temperature. The results indicate that the hydrolytic stability of cured MUF resin is lower than that of cured UF resin. The melamine decreases the hydrolytic stability of cured MUF resin by increasing the branched degree of cured MUF resin. The melamine added at different stages affects the branching structure of cured MUF resins in different ways.

Superior spectral fluorescence signature of novel illuminated melamine resin for industrial explosive detection

It is widely-accepted that explosive materials are electron deficient. The exposure of fluorescent material to explosive vapors could hold back electron movement with fluorescence quenching. We report on the porous melamine-based resin (MF) as a novel sensing element regarding explosive vapors detection. MF resin's average pore diameter is 94.7 (Å) and, a surface area of 162 m2/g could effectively-adsorb explosive vapors via its porous structure. MF resin confirmed unique fluorescent properties over visible band 400–450 nm, and infrared band 700–800 nm when illuminated with 385 nm UV laser light. The fluorescence light signal was quenched as MF resin, and was subjected to ammonium nitrate (the most common industrial explosive material). These novel optical properties could be ascribed to wired series of π bonds, and lone pairs of an electron, along the macromolecule chain. The aligned series of electron donor sites could offer a high affinity to capture explosive molecules and could strengthen the chemosensory response. Fluorescence/quenching signal was precisely-recorded using hyperspectral imaging beside a 2D moving average filter.

Response surface optimization for improving the processing behavior of melamine formaldehyde impregnation resins

AbstractMelamine‐formaldehyde resins are widely used for decorative paper impregnation. Resin properties relevant for impregnation are mainly determined already at the stage of resin synthesis by the applied reaction conditions. Thus, understanding the relationship between reaction conditions and technological properties is important. Response surface methodology based on orthogonal parameter level variations is the most suitable tool to identify and quantify factor effects and deduce causal correlation patterns. Here, two major process factors of MF resin synthesis were systematically varied using such a statistical experimental design. To arrive at resins having a broad range of technological properties, initial pH and M:F ratio were varied in a wide range (pH: 7.9–12.1; M:F ratio: 1:1.5–1:4.5). The impregnation behavior of the resins was modeled using viscosity, penetration rate and residual curing capacity as technological responses. Based on the response surface models, nonlinear and synergistic action of process factors was quantified and a suitable process window for preparing resins with favorable impregnation performance was defined. It was found that low M:F ratios (~1:2–1:2.5) and comparatively high starting pHs (~pH 11) yield impregnation resins with rapid impregnation behavior and good residual curing capacity.

A novel route to enhance the ductile performance of MF resins by addition of polyamide amine (PA)

Addition of small proportions of polyamide amine to MF resins for the purpose of resin impregnation yields a considerable improvement in both paper toughness and tensile fracture strength. The fracture strain of impregnated paper with modified resin was enhanced by more than 100% (1.08%) as compared to comparable impregnation with neat MF resin (0.49%) without sacrificing the tensile strength.

Synthesis and characterization of mixed alkanes microcapsules with phase change temperature below ice point for cryogenic thermal energy storage

The purpose of this study was to synthesize microencapsulated phase change materials (MEPCMs) with C12-C14 binary alkanes as phase change materials (PCMs) and melamine-formaldehyde resins (MF resins) as shell materials by in-situ polymerization. SDS, Span80 and Tween80 were used as the compound emulsifiers. The effects of emulsifier concentrations, core/shell ratio and compound emulsifier Hydrophilic Lipophilic Balance (HLB) value on the performance of MEPCMs were investigated. The morphology, chemical structure, thermodynamic properties and thermal stability of MEPCMs were determined by SEM, FT-IR, DSC and TGA. Results show that the emulsifier concentration and HLB value have significant impact on the MEPCMs synthesis. The emulsifier concentration of 8 wt%, HLB value of 12.15 are recommended to obtain the MEPCMs with smoother and more regular morphologies. Generally, the enthalpy and encapsulation efficiency are increasing with the increase of core/shell ratio, and the supercooling degree of MEPCMs increases by increasing the emulsifier concentration. The synthesized MEPCMs present good thermal durability and excellent cycling characteristics during the 100 thermal cycles. Moreover, they also have an appreciable thermal stability and can withstand temperatures no higher than 315 °C.

Effect of Several Exterior Adhesive Types on Dimensional Stability of Bamboo Oriented Particleboard

The objective of this research is to evaluate the effect of adhesive types on dimensional stability of bamboo-oriented particleboard. The materials used in this research are bamboo tali(Gigantochloa apus J.A & J.H. Schult. Kurz), UF/MDI(8, 10, 12 % level), and MF, MDI, and PF at 7 % level. Particle and adhesive are mixed using a blending machine; then, mat forming and hot pressing processes are performed using adhesive-suitable temperature and time references. MDI resin is set at 160 °C temperature for 5 minutes. PF resin and MF resin are pressed at 170 °C for 10 minutes, and 140 °C for 10 minutes, respectively, while UF/MDI sets at temperature of 140 °C for 10 minutes. The results show that particleboard using PF resin produces the lowest thickness swelling value. The particleboard using UF/MDI resin also produces good response for thickness swelling value. Interesting things happen in that UF/MDI adhesive produces a thickness swelling value better than that of MDI resin. FTIR analysis on particleboard bonded by UF/MDI resin combination shows the presence of carbonyl group C=O vibration on multi substitution of urea at wave number of around 1,700 cm-1.

Co3O4-nanoparticle-entrapped nitrogen and boron codoped mesoporous carbon as an efficient electrocatalyst for hydrogen evolution.

Co3O4-nanoparticle-entrapped nitrogen and boron codoped mesoporous carbon was synthesized via the molten salt method. Melamine formaldehyde resin (MF resin) was used as the nitrogen and carbon precursor, and boric acid was utilized as the boron precursor. Furthermore, cobalt chloride was used as the cobalt precursor and the template for the formation of mesopores, which could also be removed and partly recovered by acid washing. The characterization results revealed that the as-obtained samples possessed mesoporous structures, with high cobalt, boron, and nitrogen content values. For the sample of Co0.65B0.3NC800, the atomic content values of Co, N, and B are 2.3%, 8.87%, and 8.67%, respectively. Moreover, the carbonation temperature and the amount of salt template could both affect the mesoporous structures of the final samples and then affect the electrocatalytic activities for the hydrogen evolution reaction (HER). When the carbonation temperature was 800 °C, the sample of Co0.65B0.3NC800 showed superior performance for the HER under basic conditions, with high current density, low overpotential, and good stability.

Development and electrical conductivity of PVA/MF-based nanocomposite doped with NiO nanoparticles

Development of PVA-MF blends encapsulated with NiO nanoparticles to prepare moisture-resistant polymer nanocomposite films. The preparation of PVA-MF blend was carried out by blending of MF resin and prepared PVA solutions in various ratios (2% PVA and different volumes of MF, i.e., 1.3 ml (N1), 2.2 ml (N2), 2.7 ml (N3), 3.6 ml (N4), and 4.4 ml (N5)] to optimize their ratio for nanocomposite preparation. The nanocomposite films were prepared by dispersion of NiO nanoparticles in the different ratio [N3 (0.03), N3 (0.06), N3 (0.09), and N3 (0.1)] in the optimized PVA-MF blend (N3) system. The structure, physicochemical properties, and morphology of a prepared blend and polymer nanocomposites were characterized by Fourier transform infrared (FTIR), ultraviolet-visible (UV-visible) spectroscopy, X-ray powder diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The analysis reveals that the blend and polymer nanocomposite was successfully synthesized. Electrical conductivity of PVA-MF blend (N3) has been dramatically enhanced from 0.0258 ± 0.00129 to 0.3355 ± 0.01678 S/m and reduction in the band gap of nanocomposite from 5.1 to 4.8 eV as compared to blend by doping NiO nanoparticles. The synthesized polymer nanocomposite will be used for the development of new material in electrical fields.

Co-entrapped, N-doped mesoporous carbons prepared from melamine formaldehyde resins with CoCl2 as template for hydrogen evolution

Cobalt-entrapped, nitrogen-doped mesoporous carbon materials have been prepared using melamine formaldehyde resin (MF resin) as precursor and CoCl2 as template. A fraction of CoCl2 can be reduced to Co nanoparticles and wrapped by the nitrogen doped carbon. Meanwhile, the ratio of MF resin to CoCl2 is an important parameter determining the mesoporous structures of the final products. The surface area of the obtained material decreases with the increase in the ratio of MF resin to CoCl2. Electrocatalytic tests show that the obtained catalysts are highly active for hydrogen evolution reaction in both acidic and basic media, achieving a current density of 10 mA cm−2 at 171 and 186 mV under acidic and alkaline conditions, respectively. Additionally, these catalysts also show good long-term stabilities.

Nitrogen-doped mesoporous carbon-armored cobalt nanoparticles as efficient hydrogen evolving electrocatalysts

A series of Co nanoparticles embedded, N-doped mesoporous carbons have been synthesized through chelate-assisted co-assembly strategy followed by thermal treatment. The preparation is based on an assembly process, with evaporation of an ethanol–water solution containing melamine formaldehyde resin (MF resin) as carbon source, nitrogen source, and chelating agent. Moreover, F127 and Co(NO3)2 are used as template and metallic precursor, respectively. The Co nanoparticles embedded, N-doped mesoporous carbon annealed at 800 °C (denoted as MFCo800) shows high electrocatalytic activity for hydrogen evolution reaction (HER) with high current density and low overpotential, which has the ability to operate in both acidic and alkaline electrolytes.

Preparation and characteristics of Aziridine-Benzoguanamine-Urea-Melanmine-Formaldehyde resins

In this study, the effect of Aziridine (AZ) addition on the properties of the BG-MF and BG-U-MF resin, such as the mechanical strength, tensile strength, moisture adsorption, and limited oxygen index, were studied in details. The best performance was obtained for modified resins with 2 wt. % added AZ. The structure characteristics of the modified MF resins were investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). It was found that the characteristic absorption peak of the hydroxyl group and the ring of the three triazine group was significantly reduced, which indicated that the addition of aziridine was beneficial to the curing reaction. It could be seen that the effect of the addition of aziridine on the crystallinity of BG15% modified resin was not obvious, but the crystallinity of BG15%+U20% modified resin was reduced. The tensile strength and elongation at break increased after the addition of 2% aziridine, and resistance to burning and boiling water were also improved.

Improving coating properties of shellac–epoxidised-novolac blends with melamine formaldehyde resin

PurposeThe purpose of this study is to improve the coating properties of shellac–epoxidised novolac blends by treatment with melamine formaldehyde resin (MF) at ambient temperature for its use as a coating material.Design/methodology/approachEpoxidised-novolac resin was synthesised by epoxidation of novolac resin with epichlorohydrin. Novolac resin was synthesised by reaction of phenol with formaldehyde in acidic medium. Shellac was blended with the epoxidised-novolac resin in solution in varying ratios and treated the blends with MF resin in fixed ratio. Coating properties of the treated compositions were studied using a standard procedure. The compositions were characterised with Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) spectroscopy.FindingsTreatment of shellac–epoxidised-novolac blends with MF resin improved water and alkali resistance of the blends, besides enhancing gloss. Gloss in all the blends was uniformly increased on treatment with MF resin. Water resistance of the blends tremendously improved after treatment with MF resin. Contact angle of the blends against water increased while decreased against ethylene glycol and dioxane. The compositions were more resistant to polar solvent than non-polar ones, suggesting that the compositions shifted to hydrophobic (lipophilic) nature on treatment with the MF resin.Research limitations/implicationsA specified concentration of MF resin was used in the study. Different concentrations of the MF resin can also be tried for treatment of shellac–epoxidised-novolac blends to see the effect of the resin on the blends.Practical implicationsTreatment of shellac–epoxidised-novolac blend with MF resin improved the coating properties of the blends. The formulation SeNB-64 is the best with high gloss, good impact, scratch hardness and water resistance, and hence can be used as coating material for metal surfaces.Originality/valueBlending of shellac with epoxidised-novolac resin and treatment of the blends with the MF resin was done for the first time. The formulation SeNB-64 can be used as coating material for metal surfaces.

Synthesis of tetra(2,2-hydroxyethylene) terephthalamide from PET waste and its application in synthesis of polyesteramide coating

PurposeThe purpose of this paper is to discuss the synthesis of polyesteramide resin from the monomer obtained from poly (ethylene terephthalate) (PET) waste and study of the structure – property relation for the same in polyesteramide coating. The purpose is also not only to just target the polymeric waste but also to study the effect of the structure of monomer obtained from such waste in final coating.Design/methodology/approachPET waste was depolymerised using diethanolamine to tetra(2,2-hydroxyethylene) terephthalamide (THETA). Four functional hydroxyl terminated monomers were generated having amide linkage as a structural part. THETA was used for the synthesis of polyesteramide resin along with fatty amide of oil, and concentration of the THETA was varied. The synthesised polyesteramide resin was cured with MF resin and tested for physico-chemical, thermal and anticorrosive properties.FindingsPET was successfully depolymerised to monomeric level using diethanolamine as a reactive agent. It is observed that as the concentration of THETA increases, the hardness of the coating increases, as aromatic concentration increases in the coating. The amide linkage helps to improve adhesion as well as hydrophobicity because an aliphatic long chain of fatty amide and aromatic linkage of THETA helps in improving anticorrosive properties of the coating.Practical implicationsThis method is the useful key to solve the polymeric waste problem. PET can be easily depolymerised using diethanolamine and polyesteramide resin synthesised from it. Hence, waste material can be converted into the coating by reacting it with renewable resources.Originality/valueTo the best of the authors’ knowledge, this is the first study which uses THETA as a monomer for the synthesis of polyesteramide resin and study of its various concentrations on coating properties. The coating is obtained from waste material; hence, polymeric waste issue is also solved, and dependency on the petroleum resources to obtain raw materials for coating is also depleted partially. The study also helps to understand the effect of the structure of monomers on the properties of the coating.