Low Formaldehyde Research Articles

Honeycomb Molding - Forming Thermoplastic Sandwich Structures for Interior Applications

Trains play an important role in the sustainable mobility of the future. The changes in the market are reflected in the number of newly approved series by the German Federal Railway Authority (EBA); 226 new designs and redesigns of train cars were approved for use on German rails in 2019. Phenol-formaldehyde resins are used extensively specifically for railcar interiors. However, phenol-formaldehyde resins release carcinogenic vapors during and even after production if not completely sealed. As a result, European production standards and requirements have been increased, making the material less economical and increasingly difficult to enter the market. Further bans aimed at lower formaldehyde release limits are currently being considered by the European Union's Committee for Risk Assessment (RAC) and Committee for Socioeconomic Analysis (SEAC). In order to develop and design alternative materials, it is important to meet the requirements for stiffness, light weight, insulation and sustainability simultaneously. This research aim is therefore to develop a new class of material for interior components with improved stiffness, lower weight, lower CO2 footprint and no health hazards. The approach is to develop advanced composite sandwich panels that retain the ability to be molded into complex structures for interior applications. This is done through a thermoplastic honeycomb core structure that is manufactured directly from sheet material and fiber reinforced organo-sheets as the outer layers. The base matrix for all layers is kept uniform for better recyclability and consists of polycarbonate (PC) with sufficient flame retardant properties to provide an environmentally friendly alternative to existing phenolic resin and aramid epoxy honeycomb solutions while still complying with the security norms.

Study on Innovative Laminated Flooring with Resin-Impregnated Paper

A new type of laminated flooring decorated by resin impregnated paper (LWFWRIP) was designed, with the advantages of low formaldehyde emission, improved flame retardant, and high wear resistance. The structure of this new type of wood flooring is based on the ordinary laminated flooring, followed by a decorative layer of thin wood pieces, and then the transparent improved flame retardant, wear-resistant paper is added to the top. It is found that the hot-pressing temperature is the most significant factor affecting the adhesion of resin impregnated paper. The optimal hot-pressing parameters are selected as the hot-pressing pressure of 3.5 MPa, hot-pressing temperature of 180 °C, and hot-pressing time of 40 s. The new laminated flooring was improved with high flame retardant, high wear-resistant, combined with the conventional advantages of both solid wood composite flooring and reinforced wood flooring. The new laminated flooring decorated by resin impregnated paper has broad application prospects.

The impact of altering the molar ratio on formaldehyde content and the physical and mechanical properties of MDF panels

This study aimed to evaluate the influence of the molar ratio of urea-formaldehyde resin (UF) on formaldehyde content and the physical and mechanical properties of MDF panels. The goal was to determine the optimal composition, i.e. the one that exhibits the lowest formaldehyde content without compromising the properties. To that end, there were five treatments. They were characterized by five F:U molar ratios (0.9:1; 1.0:1; 1.1:1; 1.2:1; and 1.3:1). The panels had a nominal density of 750 kg.m−3, dimensions of 40 × 40 × 1.5 cm, 12% resin, 1% paraffin. They were produced with a pressing cycle with a temperature of 170 °C and pressure of 3.6 MPa per 10 min. The physical-mechanical properties of the panels and the formaldehyde content were determined and evaluated following the NBR 15316-2 (2019) standard. Results showed that the formaldehyde content was lower for panels produced with resin molar ratios of 0.9:1, 1.0:1, and 1.1:1, classified as E1. Panels with a resin molar ratio of 1.2:1 were classified as E2. The molar ratio of 1.3:1 exceeded the limits of the standard. Panels with resin molar ratios of 1.1:1, 1.2:1, and 1.3:1 met the standard requirements for all physical-mechanical properties of non-structural MDF for use in dry conditions. These results indicate that the most suitable UF resin molar ratio for producing MDF panels is 1.1:1. This radio provides low formaldehyde content and technological properties compatible with the reference standard.

Phenolation to Improve Hardwood Kraft Lignin for Wood Adhesive Application.

Lignins, naturally occurring aromatic polymers with phenylpropane units, are promising bio-based alternatives for petroleum-based products. Resole-type phenol formaldehyde (PF) adhesive is commonly used in wood composites requiring durability and weather-proofness. However, PF adhesive is a petroleum-based product. The objective of this study is to transform the low-reactivity hardwood kraft lignin (KL) as the phenol substitute in the PF adhesive formulation by acidic phenolation. The variations in the molecular weights, chemical structures, and functional groups in lignins were investigated before and after the phenolation. The results indicate that the KL can be cleaved, and phenols are crosslinked onto KL to produce phenolated kraft lignin (PKL) under the suitable phenolation condition, heating 3/5 (w/w) of KL/phenol at 90 °C for 2 h with 5% H2SO4 as the catalyst. Resole-type PKL-PF adhesives can be directly synthesized after the phenolation in the same reactor. Plywood laminated with this adhesive obtains satisfactory strength and low formaldehyde emission. This not only reduces the usage of petroleum-based phenol but also increases the reactivity and applications for hardwood KL.

Employing a mixture of fine-particle PKS, glycerol, and citric acid as an eco-friendly binder for plywood production from rubberwood (Hevea brasiliensis) veneer

Biomass-based adhesives, which are environmentally friendly and sustainable materials enabling low formaldehyde wood composites, have garnered interest. Therefore, palm kernel shells (PKS), available as industrial agricultural residue and rich in lignin, are mixed in form of fine particles with glycerol and citric acid, and tested as a candidate for binder in plywood production. The study focused on examining the effects of two factors: the quantity of adhesive used and the pressing temperature. Glycerol and citric acid are low-cost non-toxic chemicals that activate the functional groups and induce changes in the PKS component during hot pressing. Consequently, the mixtures with PKS as fine particles could cross-link with rubberwood veneer, forming a plywood panel with shear strength and bending strength that meet the requirements outlined in ISO 12466-2: part 2, and in Thai industrial standard (TIS 178-2549) for indoor use. The properties of plywood were primarily influenced by the pressing temperature rather than by the quantity of adhesive. Specifically, the temperatures 180 °C and 200 °C enhanced the extent to which the molten binder penetrated the rubberwood surface, consequently improving the mechanical properties and water resistance of the bonding.

Acidic deep eutectic solvent as a novel catalyst for urea–formaldehyde resin curing

ABSTRACT The effect of a novel catalyst, acidic deep eutectic solvent, on the characteristics of urea–formaldehyde (UF) resins-bonded particleboard was studied in this research work. Methyltriphenyl-phosphonium bromide–protocatechuic acid (MTPPBr–PCAT) as a DES was added to the UF resin at different percentages (1%, 2%, and 3% by weight). Then, the prepared resin was used for manufacturing particleboards. Based on this research finding, DES appears to be an effective UF resin catalyst. Increasing the MTPPBr–PCAT–DES level from 0 to 3 wt% caused a decrease in pH but still within the limits acceptable to international standards requirements, and also it caused a shorter gel time and acceleration of resin curing. Wood particleboard prepared with only 1 wt% DES had higher mechanical strength and dimensional stability and lower formaldehyde emission compared to the controls bonded with UF resins catalyzed with 2 wt% NH4Cl. Under scanning electron microscopy, acidic deep eutectic solvent catalyzed UF resins-bonded panels presented a smooth and monotonous appearance. DESs as UF acidic catalysts present advantages, such as being non-toxic, being able to catalyze resin cure similarly or more effectively than the acid itself, and being recyclable as well.

Eco-friendly fiberboards with low formaldehyde content and enhanced mechanical properties produced with activated soybean protein isolate modified urea-formaldehyde resin

Urea-formaldehyde (UF) resin is one of the most widely used resin adhesive for wood-based panels. The main concern of UF resin bonded wood-based panels is formaldehyde emission and poor water resistance. In this study, activated soybean protein isolate (SPI) was used to modify UF resin for the production of eco-friendly fiberboard panels. The effects of different activated SPI on the properties of UF resins and the resin bonded medium-density fiberboard (MDF) panels were investigated. The free formaldehyde content of the urea-activated SPI modified UF resin was only 0.13 %. Approximately 27.8 % lower than that of the unmodified UF resin. The resin bonded MDF panel with a density of 760 kg/m3 shows a modulus of rupture (MOR) and modulus of elasticity (MOE) of 45.73 MPa and 4005 MPa, which is increased by 25 % and 15 % compared to the unmodified UF resin group. The internal bonding strength (IB) reaches 0.71 MPa, which is about 15 % higher than that of the unmodified UF resin group. The tested 24-hour thickness swelling (24 h TS) of the modified UF resin group is only 8.1 %. The tested formaldehyde content of the sodium dodecyl sulfate (SDS)-activated SPI modified UF resin bonded MDF panel is only 4.8 mg/100 g, which is 20 % lower than that of the control UF resin group. The activated SPI modified UF resin shows great improvement in bonding strength and lower formaldehyde content for MDF panels as compared to the pure UF resin. The chemical groups, crystalline properties, and thermal stability of the pure and the modified UF resins were characterized via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric (TG) analysis. It is confirmed that the activated SPI modified UF resin has similar chemical structure, higher ratio of crystalline regions, and slightly lower thermal stability with compared to the pure UF resin. This study proposes a practical and applicable solution for the utilization of eco-friendly UF resin in wood-based panel production.

Reduction of formaldehyde emission from urea-formaldehyde resin by maleated nanolignin

In the present work, urea-formaldehyde (UF) resin was modified by maleic anhydride-modified nanolignin. For this purpose, nanolignin was prepared by an acidic method and then different ratios of virgin lignin, nanolignin and maleated nanolignin (10, 20 and 30 wt%) were added to the UF resin during its synthesis. The synthesized resins were then used in plywood panels manufacturing. The physicochemical and thermal properties of the prepared resins were determined. Formaldehyde emission, water absorption and shear strength of the plywood panels bonded with the modified resins were also measured according to the relevant standards methods. FTIR analysis indicated that the peak corresponding to O–H was decreased by the treatment of nanolignin with maleic anhydride. The intensity of the 2800 cm−1, 1200 cm−1 and 1700 cm−1 bands related to respectively C–O, CC and COOH bonds also increased in maleic anhydride-treated nanolignin. Based on the physicochemical results obtained, the modification of nanolignin by maleic anhydride accelerates the gelation time and increases the viscosity of the lignin-urea-formaldehyde (LUF) resin compared to when virgin nanolignin was used. DSC analysis shows that the addition of maleated nanolignin significantly decreases the curing temperature of the LUF resin. Based on panel analysis results, lower formaldehyde emission and higher mechanical strength and dimensional stability were obtained by treating nanolignin with maleic anhydride.

Investigation of the Formaldehyde-Catalyzed N[sbnd]Nitrosation of Dialkyl Amines: An Automated Experimental and Kinetic Modelling Study Using Dibutylamine

The potential for drug substances and drug products to contain low levels of N-nitrosamines is of continued interest to the pharmaceutical industry and regulatory authorities. Acid-promoted nitrosation mechanisms in solution have been investigated widely in the literature and are supported by kinetic modelling studies. Carbonyl compounds, particularly formaldehyde, which may be present as impurities in excipients and drug product packaging components or introduced during drug substance manufacturing processes are also known to catalyze nitrosation, but their impact on the risk of N-nitrosamine formation has not been systematically investigated to date. In this study, we experimentally investigated the multivariate impact of formaldehyde, nitrite and pH on N-nitrosation in aqueous solution using dibutylamine as a model amine. We augmented a published kinetic model by adding formaldehyde-catalyzed nitrosation reactions. We validated the new kinetic model vs. the experimental data and then used the model to systematically investigate the impact of formaldehyde levels on N-nitrosamine formation. Simulations of aqueous solution systems show that at low formaldehyde levels the formaldehyde-catalyzed mechanisms are insignificant in comparison to other routes. However, formaldehyde-catalyzed mechanisms can become more significant at neutral and high pH under higher formaldehyde levels. Model-based sensitivity analysis demonstrated that under high nitrite levels and low formaldehyde levels (where the rate of formaldehyde-catalyzed nitrosation is low compared to the acid-promoted pathways) the model can be used with kinetic parameters for model amines in the literature without performing additional experiments to fit amine-specific parameters. For other combinations of reaction parameters containing formaldehyde, the formaldehyde-catalyzed kinetics are non-negligible, and thus it is advised that, under such conditions, additional experiments should be conducted to reliably use the model.

Modified plywood binder preparation process: The effect of urea formaldehyde mole ratio

The paper highlights the importance of reducing formaldehyde emissions in plywood products due to increasing public health awareness. Lowering the formaldehyde to urea mole ratio (F/U) during UF resin preparation is a crucial step in achieving this goal. The study focuses on synthesizing UF resin through alkaline-acid process modification involving a strong acid step at the initial stage with a target viscosity range of 120 140 cP. Different F/U ratios were investigated at various condensation steps, with final molar ratios ranging from 1.5 to 1.0. Results indicate that adjusting the F/U ratio during the fourth condensation step (F/U4) is essential to meet desired viscosity requirements. Lower F/U4 ratios lead to decreased reactivity and reduced free formaldehyde content. Resin aging resulted in increased viscosity and gel time, but all resins remained suitable for application for up to three weeks after preparation. Application tests revealed that UF resin with lower F/U4 ratios produced plywood with reduced internal bonding (IB) strength and formaldehyde emissions. F/U4 = 1.1 was found to be the lowest acceptable molar ratio, with formaldehyde emissions of approximately 2 mg/L. These findings stress the importance of optimizing the UF resin synthesis process to achieve lower formaldehyde emission plywood products.

Lignosulfonate and glycidyl ether modified urea formaldehyde wood adhesives for interior particleboard production

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.

Melamine Acetate Preparation as a Urea-Formaldehyde Resin Additive for Particleboard Production

Urea-formaldehyde (UF) resin binders for wood-based panel production often use melamine as an additive to improve both mechanical properties and environmental compliance. Direct fortification for efficient use of melamine remains a problem due to low solubility. Pizzi & coworkers suggested the use of more soluble melamine salts and demonstrated success in terms of product performance. However, their preparation method showed low productivity and inefficient use of material and energy. In their scheme, a batch reactor fed with 1 kg of water and 75 g of a stoichiometric amount of melamine and acetic acid produced only around 25 g of solid melamine acetate crystal. In contrast, the remaining 50 g remained dissolved in 991 g of water, which requires high of energy to evaporate. This paper reports an attempt to increase batch productivity and work towards the more efficient use of material and energy. The experiment showed that the successive addition of melamine and acetic acid to the batch up to the solubility limit of melamine at the same reaction condition increased melamine and acetic acid fed from 75 g to 165 g. This was followed by a significant increase in dry crystal yield from 25 g to 117 - 132 g. Feeding the mother liquor to the next batch decreased the water use to only 8% of the original requirement. This resulted in a highly efficient process, eliminating the need for energy-intensive melamine acetate recovery from the mother liquor. The addition of 2% - 4% wt. of the product to UF resin resulted in particleboard with significantly lower thickness swelling, an increase in MOR & IB strength, and lower formaldehyde emission.

Recycling of Waste Bamboo Biomass and Papermaking Waste Liquid to Synthesize Sodium Lignosulfonate/Chitosan Glue-Free Biocomposite.

The development of the paper industry has led to the discharge of a large amount of papermaking waste liquid containing lignosulfonate. These lignin black liquids cause a lot of pollution in nature, which runs counter to the current environmental protection strategy under the global goal. Through the development and use of lignosulfonate in papermaking waste liquid to increase the utilization of harmful substances in waste liquid, we aim to promote waste liquid treatment and reduce environmental pollution. This paper proposes a new strategy to synthesize novel glue-free biocomposites with high-performance interfacial compatibility from papermaking by-product sodium lignosulfonate/chitosan (L/C) and waste bamboo. This L/C bamboo biocomposite material has good mechanical properties and durability, low formaldehyde emissions, a high recovery rate, meets the requirements of wood-based panels, and reduces environmental pollution. This method is low in cost, has the potential for large-scale production, and can effectively reduce the environmental pollution of the paper industry, promoting the recycling of biomass and helping the future manufacture of glue-free panels, which can be widely used in the preparation of bookcase, furniture, floor and so on.

A Study of the Properties of UV-Aged and Low Formaldehyde Emissions Particleboards Manufactured with Bio-Based Wood Protein Adhesives

The environmental crisis and the safeguarding of the population's health has led to research into different ways of mitigating harmful gases. Among the emissions that the wood industry has sought to reduce are those of formaldehyde, which is why new green adhesive methods for wood panels have been investigated in recent years. In this research, particleboard with two bio-based wood adhesive (PB-bbwa) formulations. The first PB-bbwa formulation, based on proteins obtained from compounds from the alcoholic beverage industry, and the second PB-bbwa formulation, based on proteins from a mixture of compounds from the alcoholic beverage and food industries, were manufactured and tested to evaluate the physical–mechanical, thermal and formaldehyde emission properties of untreated and UV-treated formulations at a laboratory scale. The results of the physical properties obtained in the PB-bbwa were similar or even better than those of the control PB. Additionally, PB-bbwas improve on the control PB sample’s Janka hardness by least 28%, and a decrease in thermal conductivity in the edgewise position and formaldehyde emissions by 12% and 88%, respectively, in comparison to the control PB. The tests performed evidenced that PB-bbwas showed comparable performance against the control PB made with urea-formaldehyde and satisfied international standard requirements.

The characterizations of nanofluid type urea formaldehyde resins

For reducing the emission of formaldehyde, urea formaldehyde (UF) resin adhesives used in the wood-based panel industry are mainly synthesized by adding urea in stages to reduce the molar ratio of formaldehyde and urea. Although the lower molar ratio UF resin has lower formaldehyde emissions, it also has the defects of longer curing time and lower bonding strength when being used in wood-based panel products. In this study, nanofluid type UF resins adhesives were prepared by dispersing SiO2 and TiO2 nanoparticles with six concentrations levels, 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1% into UF resins with 1.0 and 1.3 M ratio by the assistance of ultrasound, respectively. It was found that the excellent thermal conductivity of the nanofluid type adhesives could eliminate the defects of the low molar ratio UF resins. When nano-SiO2 and nano-TiO2 were incorporated, the viscosity increased as the nanoparticles concentration increased, the maximum viscosity increased by 11.7% (1.0UF) and 15.0% (1.3UF) with nano-SiO2, the free formaldehyde content, curing time, and pot life of UF resins declined in varying degrees with nanoparticles loading level increased, the maximum amount of free formaldehyde content reduced by 41.2% (1.0UF) and 43.9% (1.3UF) with nano-TiO2, the maximum reduction of curing time was 25.80% (1.0UF) and 42.6% (1.3UF) with nano-TiO2, the pot life maximum decreased by 39.7% (1.0UF) and 43.0% (1.3UF) with nano-SiO2. Nanofluid type UF resins had much higher bonding strength with lower formaldehyde emission than pristine UF resins after being treated with same hot-pressing in plywood manufacture. The maximum of bonding strength increased by 28.1% (1.0UF) and 28.8% (1.3UF) with nano-SiO2, and the maximum amount of formaldehyde emissions reduced by 48.7% (1.0UF) with nano-SiO2 and 41.9% (1.3UF) with nano-TiO2. Meanwhile, the results showed that nanofluid type UF resin used in plywood manufacture exhibited the ability to decrease the hot-pressing temperature or shorten the hot-pressing time.

Measuring low formaldehyde exposure values in the dissection hall after embalming human body donors with ethanol-based fixation methods

The dissection course plays a central role in teaching anatomy and body donors are also needed in clinical-anatomical courses. In order to reduce formaldehyde exposure of students, participants and staff during these courses, we employed fixation solutions with low formaldehyde content. In this study, we present two ethanol-based protocols, and elucidate their suitability for the dissection process and compliance with occupational exposure limits for formaldehyde and other hazardous substances. Body donors were fixed according to an ethanol- based fixation protocol for the dissection course or an ethanol-glycerin-based fixation protocol for specialist training courses. The quality of fixation was determined during the dissection process. Exposure to hazardous substances (formaldehyde, ethanol, 2-phenoxyethanol) was measured in a regular dissection course setting at different locations (room-related and person-related measurements), and exposure indices were calculated. The quality of fixation of both methods was good and fulfilled all requirements of the student dissection course and the specialist training courses, respectively. Exposure to all hazardous substances remained well below the exposure limits. Room-related air concentration measurements were 0.073/0.058 mg/m³ (2016/2017) for formaldehyde and 65/107 mg/m³ (2016/2017) for ethanol. Person-related measurements amounted to 0.107-0.229 mg/m³ for formaldehyde and 268- 388 mg/m³ for ethanol. Room-related and person- related concentrations of 2-phenoxyethanol remained below the detection limit. The ethanol-based embalming protocols presented here offer a good alternative for the different applications. The protocols are discussed regarding current regulations and further measures to reduce formaldehyde exposure.

Mechanical ventilation and indoor air quality in recently constructed U.S. homes in marine and cold-dry climates

Data were collected to characterize whole-house mechanical ventilation (WHMV) and indoor air quality (IAQ) in 55 homes in the Marine climate of Oregon and the Cold-Dry climate of Colorado in the U.S. Sixteen homes were monitored for two weeks, with and without WHMV operating. Ventilation airflows; airtightness; time-resolved CO2, PM2.5 and radon; and time-integrated NO2, NOX and formaldehyde were measured. Participants provided information about IAQ-impacting activities, perceptions and ventilation use. All homes had operational cooktop ventilation and bathroom exhaust. Thirty homes had equipment that could meet the ASHRAE 62.2–2010 standard with continuous or controlled runtime and 34 had some WHMV operating as found. Thirty-five of 46 participants with WHMV reported they did not know how to operate it, and only half of the systems were properly labeled. Two-week homes had lower formaldehyde, radon, CO2 and NO (NOX-NO2) when operated with WHMV, and had faster PM2.5 decays following indoor emission events. Overall IAQ satisfaction was similar in Oregon and Colorado, but more Colorado participants (19% vs 3%) felt their IAQ could be improved and more reported dryness as a problem (58% vs. 14%). The collected data indicate that there are benefits of operating WHMV, even when continuous use may not be needed because outdoor pollutant concentrations are low and indoor sources do not present substantial challenges.

Investigation of Electrical and Wearing Properties of Wool Fabric Coated with PEDOT:PSS.

The way to improve the properties (resistance to washing, delamination, and rubbing off) of the PEDOT:PSS coating applied on wool fabric without reduction of its electrical conductivity by introducing a commercially available combination of low formaldehyde content melamine resins into the printing paste is presented in this paper. Primarily, to improve the hydrophilicity and dyeability of wool fabric, the samples were modified using low-pressure nitrogen (N2) gas plasma. Two commercially available PEDOT:PSS dispersions were used to treat wool fabric by the exhaust dyeing and screen printing methods, respectively. Spectrophotometric measurements of the color difference (ΔE*ab) and visual evaluation of woolen fabric dyed and printed with PEDOT:PSS in different shades of the blue color showed that the sample modified with N2 plasma obtained a more intense color compared to the unmodified one. SEM was used to examine the surface morphology and a cross-sectional view of wool fabric that had undergone various modifications. SEM image shows that the dye penetrates deeper into the wool fabric after plasma modification using dyeing and coating methods with a PEDOT:PSS polymer. In addition, with a Tubicoat fixing agent, HT coating looks more homogeneous and uniform. The chemical structure spectra of wool fabrics coated with PEDOT:PSS were investigated using FTIR-ATR characterization. The influence of melamine formaldehyde resins on the electrical properties, resistance to washing, and mechanical effects of PEDOT:PSS treated wool fabric was also evaluated. The resistivity measurement of the samples containing melamine-formaldehyde resins as an additive did not show a significant decrease in electrical conductivity, while the electrical conductivity was maintained after the washing and rubbing test as well. The best results of electrical conductivity for investigated wool fabrics before and after washing and mechanical action were determined for samples subjected to the combined processing-surface modification by low-pressure N2 plasma, dyeing by exhaust with PEDOT:PSS, and coating by the screen-printing method of PEDOT:PSS and a 3 wt.% melamine formaldehyde resins mixture.

The effect of concentration extender on the making of lignin phenol-formaldehyde from coconut fibre as an environmentally friendly adhesive

This study aims to make adhesives with a variety of concentration extenders. First, the coconut husk was delignified with 25% NaOH and then precipitated with sulfuric acid. The yield of lignin from coconut coir was 38.92%, with a purity of 68%, a phenolic hydroxyl content of 2.47%, and an equivalent molecular weight of 1666.67 g/mol. Lignin was then used to synthesize phenol-formaldehyde (LPF) lignin by adding tapioca flour extender with variations of 10%, 20% and 30% of the mass of phenol through the resol method with 50% NaOH catalyst. Then the characterization was carried out using FTIR Spectrophotometer, XRD and adhesive test. The results showed that the LPF copolymer with a 10% extender was better than the LPF copolymer without an extender for wood adhesives with adhesive resistance of 955.34 N and low formaldehyde emission of 0.44 mg/L.

Performance of Six-Layered Cross Laminated Timber of Fast-Growing Species Glued with Tannin Resorcinol Formaldehyde

The aim of this study were to evaluate tannin resorcinol formaldehyde (TRF) for the preparation of cross-laminated timbers (CLTs) made from fast-growing tree species and to analyze the physical and mechanical properties of CLTs. TRF copolymer resin was prepared by using the bark extracts of Swietenia mahagoni (L.) Jacq. It was observed that the TRF adhesive possessed less solid content (23.59%), high viscosity (11.35 poise), and high pH values (10.0) compared to the standard phenol resorcinol formaldehyde. The TRF adhesive was applied to produce CLTs with the addition of 15% tapioca and flour as an extender. The six-layered CLTs were produced from sengon (Falcataria moluccana Miq.), jabon [Anthocephalus cadamba (Roxb) Miq.], coconut (Cocos nucifera L.), and the combination of coconut-jabon and coconut-sengon wood. The analysis of variance revealed that the layer composition of CLT significantly affected the physical and mechanical properties of the beam. While the modulus of rupture met the standard, the moisture content and modulus of elasticity values did not fulfill JAS 1152-2007. All of the CLTs produced in this study demonstrated low formaldehyde emission, ranging from 0.001 mg/L to 0.003 mg/L, thereby satisfying the JAS 1152 for structural glue laminated timber.