scholarly journals Analysis of Larch-Bark Capacity for Formaldehyde Removal in Wood Adhesives

2020 ◽  
Vol 17 (3) ◽  
pp. 764 ◽  
Author(s):  
Eugenia Mariana Tudor ◽  
Marius Catalin Barbu ◽  
Alexander Petutschnigg ◽  
Roman Réh ◽  
Ľuboš Krišťák
Keyword(s):  
Polyvinyl Acetate ◽  
Urea Formaldehyde ◽  
Tree Bark ◽  
Adhesive Systems ◽  
Wood Industry ◽  
Formaldehyde Content ◽  
Environmental Properties ◽  
Formaldehyde Removal ◽  
Different Types ◽  
Method Of Production

Ecofriendly wood-based materials are required by consumers at present. Decorative panels are part of a large group of wood-composite materials, and their environmental properties must not be neglected. More environmentally friendly decorative panels can be achieved by various methods. This paper describes a method of production from larch bark. Tree bark, as a byproduct of the wood industry, is one of the research topics that have gained interest in the last decade, especially for its applications in biobased lignocomposites, with regard to the shrinkage of wood resources. In the present work, the formaldehyde content of decorative boards based on larch bark (0.6 g/cm3) was analyzed when bonded with five different types of adhesive systems: urea-formaldehyde, polyvinyl acetate, the mixture of 70% urea-formaldehyde + 30% polyvinyl acetate, polyurethane, and tannin-based adhesive. A self-agglomerated board was also analyzed. The formaldehyde content of the larch-bark samples was determined with the perforator method (EN 120:2011), and findings showed that all tested samples reached the E1 classification (≤8 mg/100 oven dry). Moreover, 75% of the values of the corrected formaldehyde content were included in the super-E0 class (≤1.5 mg/100 oven dry). In the case of boards bonded with tannin-based adhesive, this natural polymer acted as a formaldehyde scavenger.

scholarly journals Eco-Friendly, High-Density Fiberboards Bonded with Urea-Formaldehyde and Ammonium Lignosulfonate

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 220
Author(s):  
Petar Antov ◽  
Viktor Savov ◽  
Ľuboš Krišťák ◽  
Roman Réh ◽  
George I. Mantanis
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Urea Formaldehyde ◽  
Physical And Mechanical Properties ◽  
High Density ◽  
Thickness Swelling ◽  
Formaldehyde Content ◽  
Uf Resin ◽  
Natural Wood ◽  
European Standards

The potential of producing eco-friendly, formaldehyde-free, high-density fiberboard (HDF) panels from hardwood fibers bonded with urea-formaldehyde (UF) resin and a novel ammonium lignosulfonate (ALS) is investigated in this paper. HDF panels were fabricated in the laboratory by applying a very low UF gluing factor (3%) and ALS content varying from 6% to 10% (based on the dry fibers). The physical and mechanical properties of the fiberboards, such as water absorption (WA), thickness swelling (TS), modulus of elasticity (MOE), bending strength (MOR), internal bond strength (IB), as well as formaldehyde content, were determined in accordance with the corresponding European standards. Overall, the HDF panels exhibited very satisfactory physical and mechanical properties, fully complying with the standard requirements of HDF for use in load-bearing applications in humid conditions. Markedly, the formaldehyde content of the laboratory fabricated panels was extremely low, ranging between 0.7–1.0 mg/100 g, which is, in fact, equivalent to the formaldehyde release of natural wood.

scholarly journals Repeated thermo-hydrolytic disintegration of medium density fibreboards (MDF) for the production of new MDF

2021 ◽  
Author(s):  
Fahriye Yağmur Bütün Buschalsky ◽  
Carsten Mai
Keyword(s):  
Service Life ◽  
Nitrogen Content ◽  
Manufacturing Process ◽  
Closed Loop ◽  
Reducing Sugars ◽  
Urea Formaldehyde ◽  
Molar Ratio ◽  
Medium Density ◽  
Target Density ◽  
Formaldehyde Content

AbstractMedium density fibreboards (MDF) are currently not recycled after service life, but various publications report on recycling by the disintegration of MDF using various techniques and the properties of obtained recovered fibres (RF). In this study, the main aim was to put back RF into the MDF manufacturing process as closed-loop recycling using repeated thermo-hydrolytic disintegration. Compared to previous studies, the focus was on the recycling of MDF with a relatively low F:U molar ratio (1.11). Urea–formaldehyde-bonded MDF with a target density of 700 kg m−3 was subjected to thermo-hydrolytic disintegration in an autoclave using only water at 95 °C for 20–30 min. Afterwards, the properties of RF and virgin fibres (VF), of MDF produced thereof and the composition of the disintegration water (DW) were determined. The nitrogen content (NC) revealed that RF contained about 30% of the initially applied UF. The pH of the DW hardly changed during recycling and it contained considerable amounts of reducing sugars. Using RF did not result in higher formaldehyde emissions than VF. Compared to earlier studies using a higher formaldehyde content (higher F:U ratio), MDF bonded with modern UF resins can be disintegrated under clearly milder disintegration conditions with respect to temperature and time. The properties of recycled MDF were similar to those of reference MDF; up to 100% RF could be used without severely deteriorating the strength and increasing formaldehyde emissions from these panels.

scholarly journals Bark Thermal Insulation Panels: An Explorative Study on the Effects of Bark Species

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2140 ◽  
Author(s):  
Günther Kain ◽  
Eugenia Mariana Tudor ◽  
Marius-Catalin Barbu
Keyword(s):  
Thermal Insulation ◽  
Mechanical Characteristics ◽  
Urea Formaldehyde ◽  
Tree Bark ◽  
Minor Effect ◽  
Explorative Study ◽  
Covering Material ◽  
Oak Tree ◽  
A Minor ◽  
Lower Bulk Density

Tree bark is a byproduct of the timber industry which accrues in large amounts, because approximately 10% of the volume a log is bark. Bark is used primarily for low-value applications such as fuel or as a soil covering material in agriculture. Within the present study, thermal insulation panels made from larch, pine, spruce, fir and oak tree bark with different resins (urea formaldehyde, melamine formaldehyde, Quebracho, Mimosa) as a binder are discussed. Also, the properties of panels made from larch bark mixed with industrial popcorn are investigated. The physical-mechanical properties of the panels, which are dependent on panel density, bark species, resin type, resin content and particle size, are analyzed. The bark species has a minor effect on the mechanical characteristics of the panels, while the compression ratio is important for the panel strength, and hence, barks with lower bulk density are preferable. Under laboratory conditions, panels made with green tannin resins proved to have adequate properties for practical use. The addition of popcorn is a means to lower the panel density, but the water absorption of such panels is comparably high. The bark type has a minor effect on the thermal conductivity of the panels; rather, this parameter is predominantly affected by the panel density.

scholarly journals Micro- and Nanofibrillated Cellulose (MNFC) from Pineapple (Ananas comosus) Stems and Their Application on Polyvinyl Acetate (PVAc) and Urea-Formaldehyde (UF) Wood Adhesives

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Priscilla Rigg-Aguilar ◽  
Roger Moya ◽  
Gloria S. Oporto-Velásquez ◽  
José Vega-Baudrit ◽  
Ricardo Starbird ◽  
...  
Keyword(s):  
Acid Hydrolysis ◽  
Polyvinyl Acetate ◽  
Urea Formaldehyde ◽  
Nanofibrillated Cellulose ◽  
Ananas Comosus ◽  
Tropical Species ◽  
Adhesion Properties ◽  
Tropical Wood ◽  
Decomposition Reactions ◽  
Hydrolysis Of

Micro- and nanofibrillated cellulose (MNFC) was extracted from pineapple stems by acid hydrolysis, then characterized and tested in two concentrations (0.5 and 1.0 wt%) in polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives. The modified adhesives were used to glue three tropical wood species (Vochysia ferruginea, Cordia alliodora, and Gmelina arborea), and their corresponding bond strength resistance was determined. MNFC and the correspondent adhesives were characterized by TGA, FTIR, SEM, TEM, AFM, and viscosity determination. The TGA analysis of MNFC showed three decomposition reactions. The SEM, TEM, and AFM evaluations demonstrated the presence of micro- and nanosized dimensions of particles after the acid hydrolysis of pineapple stems. Adding 1 wt% MNFC to PVAc and UF adhesives increased their thermal stability in similar manner. Viscosity diminished in both modified adhesives with MNFC; however, this reduction did not affect the adhesion properties in the tropical wood tested. MNFC added to PVAc and UF adhesives improved shear strength (SS) of the glue line in the three tropical species tested. The highest SS increase was obtained when adding 0.5 wt% MNFC to PVAc in V. ferruginea, and 1 wt% MNFC concentration in the case of C. alliodora and G. arborea. In the case of UF adhesives, the application of 1 wt% MNFC produced significant differences in SS for the three tropical species studied.

scholarly journals Spatial and Temporal Variation of Carotenoids in Four Species of Trentepohlia (Trentepohliales, Chlorophyta)

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Diana Kharkongor ◽  
Papiya Ramanujam
Keyword(s):  
Seasonal Changes ◽  
Quantitative Estimation ◽  
Wall Rock ◽  
Tree Bark ◽  
Carotenoid Content ◽  
Spatial And Temporal Variation ◽  
High Accumulation ◽  
Tree Barks ◽  
Significant Seasonal Variation ◽  
Different Types

Trentepohlia Martius, a dominant green subaerial alga, grows abundantly in Shillong and imparts the yellow, red, and orange colours to most of the tree barks, walls, rocks, and electric poles because of high accumulation of carotenoids in their filaments. This study emphasised the seasonal changes in carotenoid content amongst four different species of Trentepohlia, that is, T. diffracta, T. arborum, T. umbrina, and T. abietina, collected from four different substrata, that is, wall, rock, electric pole, and three types of tree bark (smooth, fissured, and rough). Quantitative estimation of different carotenoids, namely, β-cryptoxanthin, lutein, and β-carotene, from HPLC chromatogram peak showed a significant seasonal variation in all of the four species and β-carotene was threefold more in winter compared to summer. Amongst the selected species, T. diffracta collected from wall contained the highest amount of β-carotene both in summer and in winter, followed by T. arborum from rock and T. abietina from bark, and least amount was in T. umbrina collected from electric pole. Comparing the carotenoid content in Trentepohlia abietina growing in different types of barks, sample from smooth bark had the highest amount of carotenoids both in summer and in winter, followed by the sample from rough bark, and lowest amount was noted in fissured bark.

scholarly journals Effects of Adding Multiwall Carbon Nanotubes on Performance of Polyvinyl Acetate and Urea-Formaldehyde Adhesives in Tropical Timber Species

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Róger Moya ◽  
Ana Rodríguez-Zúñiga ◽  
José Vega-Baudrit
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Polyvinyl Acetate ◽  
Urea Formaldehyde ◽  
Multiwall Carbon Nanotubes ◽  
Hydroxyl Groups ◽  
Timber Species ◽  
Tropical Timber ◽  
Tropical Woods ◽  
Multiwall Carbon

Multiwall carbon nanotubes (MWCNTs) functionalized with hydroxyl groups (MWCNTs-OH) have been incorporated into polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives utilized in tropical wood gluing. The Raman spectroscopy, the atomic force microscopy (AFM), and transmission electron microscopy (TEM) were used to describe the MWCNTs-OH. The adhesives were evaluated in three concentrations of MWCNTs-OH: 0% (control), 0.05%, and 0.1%. The evaluation included color, the distribution of MWCNTs-OH by TEM and AFM, thermal stability and viscosity of the adhesives, and shear strength (SS) of the glue line for nine tropical woods. AFM and TEM confirmed interaction of MWCNTs-OH with adhesives. The viscosity of the PVAc adhesive increases with added MWCNTs-OH. The incorporation of MWCNTs-OH in PVAc and UF resin produces wood adhesives with less brightness, less yellowness, and increased redness. The nanotubes in the adhesive improved the thermal stability of the composites and increased the entropy factor and energy of activation in the kinetic decomposition of the resin. In relation to SS, MWCNTs-OH in any of the two concentrations had no significant effect on SS in dry condition in half of the species studied glued with PVAc adhesive, whereas, for UF-adhesive, the SS and percentage of wood failure improved in most of the 9 species studied.

scholarly journals INVESTIGATION OF THE STRENGTH OF SOLID WOOD BONDING WITH DIFFERENT ADHESIVES

2020 ◽  
Vol 8 (1) ◽  
pp. 203-206
Author(s):  
Ekaterina Kantieva ◽  
Larisa Ponomarenko ◽  
Maksim Posluhaev
Keyword(s):  
Tensile Strength ◽  
National Economy ◽  
Adhesive Joint ◽  
Polyvinyl Acetate ◽  
Solid Wood ◽  
Synthetic Materials ◽  
Operational Characteristics ◽  
Wood Bonding ◽  
Different Types ◽  
Industrial Use

In modern conditions of development of a national economy wood is among the most widespread constructive materials. Also, wood traditionally occupies its niche in the production of furniture and joinery. In these industries, the bonding of wood and wood materials is the main connection. Gluing of wood is made not only to give to preparations of the demanded sizes, but also improvement of operational characteristics, and also for the purpose of economy of a material. There are different types of gluing: gluing blanks in thickness and length, gluing tenon joints, gluing boards and gluing layouts on the edges of the boards, gluing with simultaneous bending, facing with wood and synthetic materials, gluing parts of soft furniture elements. The paper investigated the influence of the type of glue on the bonding strength of wood and wood materials in modern industrial use. Adhesives based on polychloroprene, polyvinyl acetate, rubber and wood materials of different species – ash and beech-were selected for the study. The tensile strength of the adhesive joint was controlled when chipping along the fibers. most suitable for gluing pieces of wood of firm deciduous breeds in the thickness and width are adhesives based on polyvinyl acetate. Noticeable differences in the strength of freshly glued seams on beech and ash are not recorded, which is explained by their almost identical density.

scholarly journals Process modification involving strong-acid step in urea-formaldehyde resin preparation

2020 ◽  
Vol 16 (2) ◽  
pp. 212-217
Author(s):  
Dicky Dermawan ◽  
Lucky William Kusnadi ◽  
Jemmy Lesmana
Keyword(s):  
Urea Formaldehyde ◽  
Gelation Time ◽  
Strong Acid ◽  
Raw Material ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
Formaldehyde Concentration ◽  
Formaldehyde Content ◽  
Process Modification ◽  
Uf Resin

Urea-formaldehyde (UF) resin adhesive for wood-based panel industries are commonly manufactured using conventional alkaline-acid process. This paper reports a process modification of a conventional UF resin preparation by incorporating a strong-acid step, involving simultaneous methylolation and condensation reactions at very low pH at the beginning of the processing step. The experiment showed that this additional step should be carried out at short duration and at high enough temperature in order to avoid gelation or separation problems. In order to control temperature rise caused by the exothermic nature of the reactions, the modified process requires a higher initial formaldehyde-to-urea (F/U) molar ratio compared to the original. For the same reason, the first urea should be fed incrementally to ensure high F/U ratio at any time during the strong acid step. Using regular formalin concentration as raw material at the same F/U molar ratio, the modified resin showed lower free formaldehyde content thus have lower reactivity in comparison to those of the original. However, when the same procedure was applied using higher formaldehyde concentration at higher solid content, the produced resin showed comparable free formaldehyde content and shorter gelation time. Application test for making plywood showed that the modified process gave a very significant improvement in both the internal bonding strength and formaldehyde emission.

scholarly journals Investigation on the Physical Properties of 100% Cotton Knit Fabric by Treating with Crossslinking Agents

2018 ◽  
Vol 8 (02) ◽  
Author(s):  
Imana Shahrin Tania ◽  
Md. Zulhash Uddin ◽  
Kawser Parveen Chowdhury
Keyword(s):  
Physical Properties ◽  
Textile Industry ◽  
Crosslinking Agent ◽  
Areal Density ◽  
Cotton Fabrics ◽  
Formaldehyde Content ◽  
Different Types ◽  
Chemical Companies ◽  
Finishing Agent ◽  
Crosslinking Agents

TApplication of crosslinking agent to impart wrinkle recovery property on cotton fabrics is very popular for textile industry. This paper represents the effect of different crosslinking agent on the physical properties and the wrinkle recovery of cotton knit fabric. Here five different types of crosslinking agent from three different chemical companies were used. The work was divided into two parts .At first; crosslinking agents were applied on cotton fabric than various related tests were done on the treated and untreated fabric. Better crease resistancy was found on the finishing agent having high formaldehyde content .The other important properties like tensile strength, dimensional stability, stiffness, abrasion resistance pilling resistance and areal density was studied here. Among them some properties were improved and some were fall down.

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