Plasma Treatment Induced Chemical Changes of Alkali Lignin to Enhance the Performances of Lignin-Phenol-Formaldehyde Resin Adhesive

Alkali lignin was processed by plasma and then used in modification of phenol formaldehyde resin in this study.Chemical structural changes of lignin which was processed by plasma as well as bonding strength,tensile property,curing performance and thermal property of the prepared phenol formaldehyde resin which was modified by the plasma processed lignin were analyzed.Results demonstrated that:(1)Alkali lignin was degraded after the plasma processing.The original groups were destroyed,and the aromatic rings collected abundant free radicals and oxygen-containing functional groups like hydroxyls,carbonyls,carboxyls and acyls were introduced into increase the reaction activity of lignin significantly.(2)The introduction of alkali lignin decreased the free formaldehyde content and increased bonding strength and toughness of the prepared phenol formaldehyde resin,especially after the introduction of lignin treated with plasma.(3)The introduction of alkali lignin led to high curing temperature for the prepared phenol formaldehyde resin,but that was reduced by the plasma processed alkali lignin.(4)The introduction of alkali lignin could also increase thermal stability of phenol formaldehyde resin,but that was modified by plasma processed alkali lignin was better than the unprocessed lignin.Based on the results,the plasma processed lignin was used to modify phenol formaldehyde resin,which could increase the strength and toughness of phenol formaldehyde resin significantly.

Synergistic Reinforcement of Phenol-Formaldehyde Resin Composites by Poly(Hexanedithiol)/Graphene Oxide

In this paper, the preparation of graphene oxide was achieved by Hummers method and the surface modification was achieved by poly(hexaneditiol), which was a synthetic thermotropic liquid crystalline polymer. The c-PHDT/GO/PF composites were prepared by blending, rolling and compression molding techniques. Then, the as-prepared samples were characterized by FTIR, Raman, XRD, TGA and POM to obtain information on their structures and properties. After that, the effects of c-PHDT/GO content on the mechanical properties, friction performance and dynamic mechanical performance of c-PHDT/GO/PF composites were studied by Mechanical and Dynamic Mechanical Analysis (DMA) methods. Also, Scanning Electron Microscope (SEM) was used for the characterization of wear and fracture surface morphology. The results revealed that the reinforcing effect of c-PHDT/GO was significant as a considerable enhancement on the mechanical performance of c-PHDT/GO/PF composite as compared to pure phenol-formaldehyde composites was observed: the impact strength, bending modulus and bending strength increased from 1.63 kJ/m2, 8.61 GPa and 41.55 MPa to 2.31 kJ/m2, 10.16 GPa and 54.40 MPa respectively at the c-PHDT/GO content = 0.75%. Moreover, the initial storage modulus increased by 28.4%, while the wear mass loss decreased by 17.8%. More importantly, the reinforcement by c-PHDT/GO was further enhanced as compared to GO/PF and p-PHDT/GO/PF composites, the impact strength of c-PHDT/GO/PF composite increased by 27.6% and 11.1%, the bending strength increased by 11.8% and 7.6%, the initial storage modulus increased by 16.2% and 4.2% and the mass loss due to wear decreased by 12.7% and 8.8%, respectively. Based on these results, we can conclude that the surface modification of GO by poly(hexanedithiol), which includes synergistic effect by c-PHDT and GO, improves the interfacial adhesion between GO and the resin matrix, thus reinforcing the composites.

Study on binder system of CO_2-cured phenol-formaldehyde resin used in foundry

A new aqueous alkaline resol phenol-formaldehyde resin has been prepared from phenol and formaldehyde using NaOH as catalyst; the optimum synthetic process has been determined. With addition of some cross-linking agents, after passing carbon dioxide gas through the resin bonded sand, high as-gassed strength and 24 h strength are achieved. The bonding bridge of the resin bonded sand fracture has been analyzed by using SEM.

Effect of Phenolation, Lignin-Type and Degree of Substitution on the Properties of Lignin-Modified Phenol-Formaldehyde Impregnation Resins: Molecular Weight Distribution, Wetting Behavior, Rheological Properties and Thermal Curing Profiles

Here,the effects of substituting portions of fossil-based phenol in phenol formaldehyde resin by renewable lignin from two different sources are investigated using a factorial screening experimental design.Among the resins consumed by the wood-based industry,phenolics are one of the most important types used for impregnation,coating or gluing purposes.They are prepared by condensing phenol with formaldehyde(PF).One major use of PF is as matrix polymer for decorative laminates in exterior cladding and wet-room applications.Important requirements for such PFs are favorable flow properties(low viscosity),rapid curing behavior(high reactivity)and sufficient self-adhesion capacity(high residual curing potential).Partially substituting phenol in PF with bio-based phenolic co-reagents like lignin modifies the physicochemical properties of the resulting resin.In this study,phenol-formaldehyde formulations were synthesized where either 30%or 50%(in weight)of the phenol monomer were substituted by either sodium lignosulfonate or Kraft lignin.The effect of modifying the lignin material by phenolation before incorporation into the resin synthesis was also investigated.The resins so obtained were characterized by Fourier Transform Infra-Red(FTIR)spectroscopy,Size Exclusion Chromatography(SEC),Differential Scanning Calorimetry(DSC),rheology,and measurements of contact angle and surface tension using the Wilhelmy plate method and drop shape analysis.

Curing reaction and mechanism of phenol-formaldehyde novolac resins for foundry

In this study on the curing dynamics of phenol-formaldehyde novolac resins(PFNR) and hexamethylene tetramine(HMTA), two typical commercial PFNR were selected as examples and the curing reactions of the resins with HMTA were studied by differential scanning calorimetry(DSC). Based on the data calculated by the Kissinger equation and the Crane equation, a thermocuring dynamic model was established, from which the process conditions, activation energy, reaction kinetics equation and a f irst-order reaction of the curing reactions were derived.

Complexation Between Borate ion and Hydroxyl Groups of Phenol-Formaldehyde Resol Resin

The complexation reaction between borate ions and phenol-formaldehyde resol resin in aqueous solution was studied by pH measurement, small model molecules and infrared spectroscopy. The results show that the complexation can proceed completely and rapidly at room temperature. Borate ion attacks phenol hydroxyl groups and adjacent position hydroxymethyl groups on the phenol ring of the resin, and forms the coordinate bond between boron atom in borate ion and oxygen atom in the hydroxyl groups. The complexation is a quantitative reaction. The complex is a six member ring containing two oxygens and one boron. The complexation can release hydrogen ions resulting in the decreasing pH in the resin solution.

SYNTHESES AND ADSORPTION PROPERTIES OF PHENOL-FORMALDEHYDE-TYPE CHELATING RESINS BEARING THE FUNCTIONAL GROUP OFTAR TARIC ACID

Several kinds of novel chelating resins bearing the functional group of tartaric acid (TTA-FQ-12, TTA-FQ-23, and TTA-FQ-34) were synthesized by reacting epoxy maleic anhydride, which was prepared through the oxidization reaction of maleic anhydride by hydrogen peroxide, with phenol-formaldehyde resin containing polyamine (FQ resins series). The effects of such factors as reaction time, reaction temperature and pH value on the loading capacity of TTA in resins were investigated. The results showed that the optimum reaction conditions are as follows: time 9-12 h; temperature 90-105'C; pH value 6-10. The loading capacities of TTA can reach 0.15, 0.14, and 0.11 mmol/g-1 when the functional group of FQ resin was - OCH2CH2NHC2H4NH2, - O(CH2CH2NH)2C2H4NH2 and - O(CH2CH2NH)3C2H4NH2), respectively. The structures of resins were characterized by FTIR spectra. The primary study on the adsorption properties of the resins for metal ions showed that there are two kinds of adsorption mechanisms i.e. ion exchange and chelate in the adsorption process. TTA-FQ resins have much higher adsorption selectivity for Pb2+and Zn2+ than for Cu2+ and Ni2+. These resins can probably be used for separating Pb2+ or Zn2+ in the mixture of metal ions or for treating wastewater containing heavy metal ions.

Particle agglomeration and inhibition method in the fluidized pyrolysis reaction of waste resin

This work investigated the pyrolysis reaction of waste resin in a fluidized bed reactor.It was found that the pyrolysis-generated ash would adhere to the surface of ceramic particles,causing particle agglomeration and defluidization.Adding kaolin could effectively inhibit the particle agglomeration during the fluidized pyrolysis reaction through physical isolation and chemical reaction.On the one hand,kaolin could form a coating layer on the surface of ceramic particles to prevent the adhesion of organic ash generated by the pyrolysis of resin.On the other hand,when a sufficient amount of kaolin(-0.2%(mass))was added,the activated kaolin could fully contact with the Na+ ions generated by the pyrolysis of resin and react to form a high-melting aluminosilicate mineral(nepheline),which could reduce the formation of low-melting-point sodium sulfate and thereby avoid the agglomeration of ceramic particles.

Preparation of Single-handed Helical and C-Shaped 3-Aminophenol-formaldehyde Resin Nanotubes and Single-handed Helical Carbonaceous Nanotubes

Single-handed helical and C-shaped 3-aminophenol-formaldehyde resin nanotubes were prepared via a supramolecular templating approach. The chiral templates and 3-aminophenol were initially organized into helical nanoribbons, followed by the adsorption of formaldehyde onto the surfaces of the helical nanoribbons. Subsequent to polymerization and further thermosetting of the resin oligomers, 3-aminophenol-formaldehyde resin nanotubes were obtained after removing the templates. When low amounts of 3-aminophenol were added, straight C-shaped 3-aminophenol-formaldehyde resin nanotubes were obtained. Increasing the amount of added 3-aminophenol led to the formation of single-handed helical nanotubes instead. When the single-handed helical resin nanotubes were car- bonized at 900 ~C under Ar, single-handed helical carbonaceous nanotubes were obtained. Raman spectrum indicates that this carbon is predominantly amorphous. Circular dichroism spectra illustrate that both the helical resin nanotubes and the carbonaceous nanotubes exhibit optical activity. This work indicates that the added amount and the edge-adsorption mode of the precursors on the templates determine the final morphology and chirality of the products.

Enhanced corrosion resistance of epoxy resin coating via addition of CeO_(2) and benzotriazole

The use of fillers to enhance the corrosion protection of epoxy resins has been widely applied.In this work,cerium dioxide(CeO_(2))and benzotriazole(BTA)were introduced into an epoxy resin to enhance the corrosion resistance of Q235 carbon steel.Scanning electron microscopy results indicated that the CeO_(2) grains were rod-like and ellipsoidal in shape,and the distribution pattern of BTA was analyzed by energy dispersive spectroscope.The dynamic potential polarization curve proved the excellent corrosion resistance of the composite epoxy resin with CeO_(2) and BTA co-addition,and electrochemical impedance spectroscopy test analysis indicated the significantly enhanced long-term corrosion protection performance of the composite coating.And the optimal protective performance was provided by the coating containing 0.3%(mass)CeO_(2) and 20%(mass)BTA,which was attributed to the barrier performance of CeO_(2) particles and the chemical barrier effect of BTA.The formation of corrosion products was analyzed using X-ray diffraction.In addition,the corrosion resistance mechanism of the coating was also discussed in detail.

Preparation of Environmentally Friendly Urea-Hexanediamine-Glyoxal(HUG)Resin Wood Adhesive

Using non-toxic,low-volatile glyoxal to completely replace formaldehyde for preparing urea-glyoxal(UG)resin adhesive is a hot research topic that could be of great interest for the wood industry.However,urea-glyoxal(UG)resins prepared by just using glyoxal instead of formaldehyde usually yields a lower degree of polymerization.This results in a poorer bonding performance and water resistance of UG resins.A good solution is to pre-react urea to preform polyurea molecules presenting already a certain degree of polymerization,and then to condense these with glyoxal to obtain a novel UG resin.Therefore,in this present work,the urea was reacted with hexamethylene diamine to form a polyurea named HU,and then this was used to react it with different amounts of glyoxal to synthesize hexamethylenediamine-urea-glyoxal(HUG)polycondensation resins,and to use this for bonding plywood.The results show that the glyoxal can well react with HU polyuria via addition and schiff base reaction,and also the HUG resin exhibits excellent bonding strength and water resistance.The shear strength of the plywood bonded with this HUG at 160°C hot press temperature as high as 1.93 MPa,2.16 MPa and 1.61 MPa,respectively,which meets the requirement of the China national standard GB/T 9846-2015(≥0.7 MPa),and can be a good choice as a wood adhesive for industrial application.

Evaluating two stages of silicone-containing arylene resin oxidation via experiment and molecular simulation

Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still remains unclear.Herein,the oxidation behavior and mechanisms of PSA resin are systematically investigated combining kinetic analysis and Reax FF molecular dynamics(MD)simulations.Thermogravimetric analysis indicates that the oxidation process of PSA resin undergoes two main steps:oxidative mass gain and oxidative degradation.The distributed activation energy model(DAEM)is employed for describing oxidation processes and the best-fit one is obtained using genetic algorithms and differential evolution.DAEM model demonstrates that the oxidative weight gain stage is dominated by two virtual reactants and the oxidative degradation stage consists of three virtual reactants.Correspondingly,the observation of MD reaction pathways indicates that oxygen oxidation of unsaturated structures occurs in the initial stage,which results in the formation of PSA resin oxides.Furthermore,cracked pieces react with O_(2)to generate CO and other chemicals in the second step.The resin matrix's great antioxidation resilience is illustrated by the formation of SiO_(2).The analysis based on MD simulations exhibits an efficient computational proof with the experiments and DAEM methods.Based on the results,a two-stage reaction mechanism is proposed,which provides important theoretical support for the subsequent study of the oxidation behavior of silica-based resins.

Preparation and Swelling Kinetic Analysis of Poly (HPMC-co-AA-co-AM) Super Absorbent Resin

Super absorbent resin(SAR)is prepared by aqueous high temperature polymerization using hydroxypropyl methylcellulose(HPMC)as monomer backbone material,acrylic acid(AA)and acrylamide(AM)as the graft copolymer monomer,potassium persulfate(KPS)as the initiator to generate free radicals,and N,N`-methylenebisacrylamide(MBA)as cross-linking agent for cross-linking reaction.Simutaneously,the influence of individual factors on the water absorption is investigated,and these factors are mainly AA,AM,KPS,MBA,HPMC,and reaction temperature.The optimized conditions are obtained by the experiment repeating for several times.The water absorption multiplicity and salt absorption multiplicity under the conditions are 782.4 and 132.5 g/g,respectivity.Furthermore,the effects of different temperatures and salt concentrations on its water absorption,as well as the swelling kinetics of SAR are studied.It is indicated the water-absorbing swelling process is mainly caused by the difference in water osmotic pressure and Na+concentration inside and outside the cross-linked molecular structure of the resin,which is not only consistent with the quasi-secondary kinetic model,but also with the Fick diffusion model.

Evaluation of the injection and plugging ability of a novel epoxy resin in cement cracks

Sustained casing pressure(SCP)is a crucial issue in the oil and gas production lifecycle.Epoxy resins,exhibiting exceptional compressive strength,ductility,and shear bonding strength,have the potential to form reliable barriers.The injectivity and sealing capacity of the epoxy resin is crucial parameters for the success of shallow remediation operations.This study aimed to develop and assess a novel solid-free resin sealant as an alternative to Portland cement for mitigating fluid leakage.The investigation evaluated the viscosity,compressive strength,and brittleness index of the epoxy resin sealant,as well as its tangential and normal shear strengths in conjunction with casing steel.The flow characteristics and sealing abilities of conventional cement and epoxy resin were comparatively analyzed in cracks.The results showed that the application of a viscosity reducer facilitated control over the curing time of the epoxy resin,ranging from 1.5 to 6 h,and reduced the initial viscosity from 865.53 to 118.71 m Pa,s.The mechanical properties of the epoxy resin initially increased with a rise in curing agent content before experiencing a minor decrease.The epoxy resin containing 30%curing agent exhibited optimal mechanical properties.After a 14-day curing period,the epoxy resin's compressive strength reached81.37 MPa,2.12 times higher than that of cement,whereas the elastic modulus of cement was 2.99 times greater than that of the epoxy resin.The brittleness index of epoxy resin is only 3.42,demonstrating high flexibility and toughness.The tangential and normal shear strengths of the epoxy resin exceeded those of cement by 3.17 and 2.82 times,respectively.In a 0.5 mm-wide crack,the injection pressure of the epoxy resin remained below 0.075 MPa,indicating superior injection and flow capabilities.Conversely,the injection pressure of cement surged dramatically to 2.61 MPa within 5 min.The breakthrough pressure of0.5 PV epoxy resin reached 7.53 MPa,decreasing the crack's permeability to 0.02 D,a mere 9.49%of the permeability observed following cement plugging.Upon sealing a 2 mm-wide crack using epoxy resin,the maximum breakthrough pressure attained 5.47 MPa,3.48 times of cement.These results suggest that epoxy resin sealant can be employed safely and effectively to seal cracks in the cement.

Kinetic Study of Curing Phenol-Formaldehyde/Tannin-Formaldehyde Composite Resins

This work presents a study on the uses of tannin-formadehyde derivative into phenolic resins. Eucalyptus tannins (T) were reacted with formaldehyde to form tannin-formaldehyde resin (TF). Then this derivative was used to prepare tannin-formaldehyde/phenol-formaldehyde resins (TFPF) at 20 and 40 %w/w. The kinetic values of thermal curing of Phenol-formaldehyde (PF), tannin-formaldehyde and tannin-formaldehyde/phenol-formaldehyde resins (TFPF) at 20 and 40 wt% from TF were studied by monitoring the weight changes which occurred in the samples weight during thermosetting process at four temperature (160°C, 180°C, 200°C and 220°C). The total evolved condensation products from curing reactions were about 32% - 36% per sample weight, and the rate of curing reaction constants was ranged between 0.163 %wt·min-1 at 160°C and 0.50 %wt·min-1 at 220°C. The path of TFPF curing and kinetic values indicated that these resins could be cured with the behavior and velocity comparable to that of PF. The activation energy of TFPF cross-linking was higher than that of PF. Increasing TF level to 20% and 40% into PF can reduce the amount of PF curing reactions density and weight loss percentage. The global kinetic properties showed that the TF participated in the thermoset network formation with acceptable activity and performance. The general results of this paper show that the TF is a suitable alternative material for partially replacement into PF resin.

A functionalized activated carbon adsorbent prepared from waste amidoxime resin by modifying with H_(3)PO_(4) and ZnCl_(2) and its excellent Cr(Ⅵ)adsorption

With the application of resins in various fields, numerous waste resins that are difficult to treat have been produced. The industrial wastewater containing Cr(Ⅵ) has severely polluted soil and groundwater environments, thereby endangering human health. Therefore, in this paper, a novel functionalized mesoporous adsorbent PPR-Z was synthesized from waste amidoxime resin for adsorbing Cr(Ⅵ). The waste amidoxime resin was first modified with H3PO4 and ZnCl_(2), and subsequently, it was carbonized through slow thermal decomposition. The static adsorption of PPR-Z conforms to the pseudo-second-order kinetic model and Langmuir isotherm, indicating that the Cr(Ⅵ) adsorption by PPR-Z is mostly chemical adsorption and exhibits single-layer adsorption. The saturated adsorption capacity of the adsorbent for Cr(Ⅵ) could reach 255.86 mg/g. The adsorbent could effectively reduce Cr(Ⅵ) to Cr(Ⅲ) and decrease the toxicity of Cr(Ⅵ) during adsorption. PPR-Z exhibited Cr(Ⅵ) selectivity in electroplating wastewater. The main mechanisms involved in the Cr(Ⅵ) adsorption are the chemical reduction of Cr(Ⅵ) into Cr(Ⅲ) and electrostatic and coordination interactions. Preparation of PPR-Z not only solves the problem of waste resin treatment but also effectively controls Cr(Ⅵ) pollution and realizes the concept of “treating waste with waste”.

Toray develops hybrid bonding insulating resin and revolutionary polymer membrane

This year,Toray Industries,Inc.,announced that it has developed an insulating resin material for hybrid bonding(micro bonding).The material is based on Semicofine™and Photoneece™.These are high-heat-resistant polyimide coatings for semiconductor and display devices.The new material combines a conventional polyimide coating agent with the company’s processing and bonding technologies.It can enhance the yields and reliability of semiconductor devices in the hybrid bonding process,which entails bonding semiconductor chips with metal electrodes.Toray will push ahead with prototyping and providing samples to customers.It aims to obtain materials certification in 2025 and start mass production by 2028.

Modification of Nano-α-Al2O3 and Its Influence on the Surface Properties of Waterborne Polyurethane Resin Composite Passivation Films

Silane coupling agent KH560 was used to modify the surface of nano-α-Al2O3 in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al2O3 was determined by nano-particle size analyzer, and the effects of nano-α-Al2O3 content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al2O3 were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al2O3 dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al2O3 increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al2O3.

Study on Physical and Mechanical Properties of Poplar Modified by Phenol-formaldehyde Resin

Impregnation method can effectively improve physical and mechanical properties of wood. In this study, plantation poplar lumbers are impregnated by a low molecular weight phenol-formaldehyde resin solution with concentration of 30% under vacuum-pressure process, and then dried and machined according to the related standards. The results show that the physical and mechanical properties of poplar can be improved by the treatment, except for toughness. The average density of poplar increases from 0.397 to 0.710 g/cm3, the modulus of elasticity in static bending, the bending strength and the compressive strength parallel to grain of treated specimens increase by 56.71%, 112.97% and 87.69%, respectively, compared to the untreated. And the hardness values on radial and tangential sections, and nail holding power as well as abrasion resistance of treated specimens improve by 283.87%, 82.78%, 71.43% and 22.06%, respectively; while toughness decreases by 48.80%.

Reinforcement of Lignin-Based Phenol-Formaldehyde Adhesive with Nano-Crystalline Cellulose (NCC): Curing Behavior and Bonding Property of Plywood

The curing behavior of lignin-based phenol-formaldehyde (LPF) resin with different contents of nano-crystalline cellulose (NCC) was studied by differential scanning calorimetry (DSC) at different heating rates (5, 10 and 20&degC/min) and the bonding property was evaluated by the wet shear strength and wood failure of two-ply plywood panels after soaking in water (48 hours at room temperature and followed by 1-hour boiling). The test results indicated that the NCC content had little influence on the peak temperature, activation energy and the total heat of reaction of LPF resin at 5 and 10&degC/min. But at 20&degC/min, LPF0.00% (LPF resin without NCC) showed the highest total heat of reaction, while LPF0.25% (LPF resin containing 0.25% NCC content) and LPF0.50% (LPF resin containing 0.50% NCC content) gave the lowest value. The wet shear strength was affected by the NCC content to a certain extent. With regard to the results of one-way analysis of variance, the bonding quality could be improved by NCC and the optimum NCC content ranged from 0.25% to 0.50%. The wood failure was also affected by the NCC content, but the trend with respect to NCC content was not clear.