Browsing by Author "Nunez-Decap, Mario"

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    A Potential Replacement to Phenol-Formaldehyde-Based Adhesives: A Study of Plywood Panels Manufactured with Bio-Based Wood Protein and Nanolignin Adhesives
    (2024) Nunez-Decap, Mario; Friz-Sanchez, Catherine; Opazo-Carlsson, Camila; Moya-Rojas, Boris; Vidal-Vega, Marcela
    Plywood production relies on phenol-formaldehyde (PF), which is why bio-based wood adhesives (BBWAs) were developed as potential replacements, showing promising results in several tests performed. A control sample (PLY-C) with PF and two samples (PLY-1 and PLY-2) with BBWA were manufactured, on which physical and mechanical properties, adhesive bonding morphology, formaldehyde emissions, and accelerated UV aging were evaluated. The adhesive penetration results, into the wood cells, were according to the viscosity of each adhesive. About the mechanical properties, the sample PLY-2 presented the same MOE and tensile strength as the sample PLY-C and reached 87% of the sample PLY-C MOR in the parallel direction. On the other hand, the sample PLY-1 presented the same behavior in the Janka hardness test as the sample PLY-C. All the samples subjected to shear strength tests met the requirement, and the samples PLY-1 and PLY-2 reached 68% and 80% of the PLY-C sample, respectively. The samples manufactured with BBWA presented a decrease in formaldehyde emissions by 88% and they were less susceptible to color change than the control sample under UV aging. According to the results obtained, it is concluded that plywood manufactured with BBWA might be a considerable replacement for plywood manufactured with PF adhesives at a laboratory scale.
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    A Study of the Properties of UV-Aged and Low Formaldehyde Emissions Particleboards Manufactured with Bio-Based Wood Protein Adhesives
    (2023) Nunez-Decap, Mario; Canales-Constanzo, Erickson; Opazo-Carlsson, Camila; Moya-Rojas, Boris; Vidal-Vega, Marcela; Opazo-Vega, Alexander
    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.
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    Comparative Study of Carbon Nanotubes and Lignosulfonate as Polyvinyl Acetate (PVAc) Wood Adhesive-Reinforcing Agents
    (2024) Vidal-Vega, Marcela; Nunez-Decap, Mario; Hernandez-Duran, Javier; Catricura-Munoz, Pedro; Jara-Briones, Catalina; Moya-Rojas, Boris; Opazo-Carlsson, Camila
    This study aimed to reinforce a polyvinyl acetate-D3 (PVAc-D3) adhesive to improve its mechanical and thermal properties. The goal was to reach a polyvinyl acetate-D4 (PVAc-D4) adhesive performance that could make PVAc-D3 more attractive and add value to wood products. PVAc-D3 was modified by adding 0.05% and 0.5% (wt.) of multi-walled carbon nanotube particles (MWCNTs) as well as 0.5% and 2.5% (wt.) of lignosulfonate (LIGNO) particles. Adhesive blends were compared to neat PVAc-D3 and PVAc-D4, evaluating their physical-chemical properties. Also, they were analyzed using Fourier transform infrared spectroscopy (FT-IR) and mechanical dynamic analysis (DMA) with a storage module (E '). The blends were used to fabricate laminated wood pieces, pressed at 60 and 120 min (min), to be tested at shear strength under dry, elevated temperature and vacuum-pressure conditions. Delamination and adhesive penetration were determined by microscopy. Incorporating fillers into PVAc resulted in a decrease in viscosity. FT-IR evidenced that the PVAc-D4 adhesive had a bigger cross-linked degree than the other adhesive samples. The DMA showed that LIGNO and MWCNT fillers help increase E ' at the bond line, reaching a higher stiffness level than neat PVAc-D3. In dry conditions, specimens glued with D3-LIGNO 0.5% at 120 min reached shear strengths that were 100%, 28%, and 3% higher than the standard requirement, PVAc-D4, and neat PVAc-D3, respectively. Also, those glued with D3-MWNTC 0.05% reached shear strengths that were 91%, 21%, and 3% higher than the standard requirement, D4, and neat D3, respectively. Only PVAc-D4 reached the standard requirement for elevated temperature and vacuum-pressure conditions. Delamination of <= 5% (standard requirement) was achieved by wood specimens glued with neat PVAc-D3, D3-MWNTC 0.5%, D3-LIGNO 0.5%, and PVAc D4 adhesive samples. In this study, it was found specific ranges of average penetration (AP) to ensure a glue line good quality. To conclude, LIGNO and MWCNT particles improved the PVAc-D3 adhesive's performance in dry conditions, but they were not very relevant to the D3 adhesive's behavior. At high temperatures, the LIGNO filler worked very well as a thermic stabilizer compared to the MWCNT filler. The solubility of the reinforcing agent can affect an adhesive's blend quality and its cohesion properties. An adequate penetration depth procures a good quality bond between an adhesive and substrate with less possibilities of delamination. An extensive pressing time may cause a weak interphase and poor mechanical properties in an adhesive bond in the presence of humidity.
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    Non-Destructive Assessment of the Elastic Properties of Low-Grade CLT Panels
    (2021) Opazo-Vega, Alexander; Benedetti, Franco; Nunez-Decap, Mario; Maureira-Carsalade, Nelson; Oyarzo-Vera, Claudio
    The use of cross-laminated timber panels (CLT) made of low-grade structural timber has steadily increased in developing countries. These panels usually present several natural defects, which can cause a high local variation of their orthotropic elastic properties, generating future structural serviceability problems. Our work aims to estimate the local variability of the elastic properties in low-grade CLT panels by combining nondestructive transverse vibration testing, numerical simulations, and regional sensitivity analysis (RSA). Four three-layer Radiata pine CLT panels were subjected to transverse vibration tests with supports at four points. Besides, a series of numerical simulations of the panels, considering the local variability of the elastic properties of the panels in eight zones, were carried out using the finite element method. Then, RSA analysis was performed to study in which ranges of values the panels' elastic properties generated lower differences between the measured versus simulated dynamic properties. Finally, a structural quality control indicator was proposed for the CLT panels based on keeping low the probability that the elastic properties in the central zones do not exceed minimum acceptable values. The results obtained suggest that the proposed methodology is suitable for segregating CLT panels with high concentrations of defects such as pith presence.
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    Preliminary study of particleboards manufactured with pine cones and Eucalyptus globulus capsules with a bio-based polyurethane adhesive
    (2022) Wechsler-Pizarro, Andrea; Nunez-Decap, Mario
    The following research aims to evaluate the feasibility of manufacturing particleboards based in Pinus radiata D. DON (PC) and Eucalyptus globulus (EC) capsules bonded with a natural oil polyurethane adhesive (PU). The particles of PC and EC were ground and dried. Particleboards were manufactured with PC and EC bonded with a natural oil-based polyurethane adhesive (PC-PU and EC-PU). Boards composed of radiata pine wood and bio based polyurethane adhesive (RP-PU) and with radiata pine wood bonded with urea formaldehyde resin (RP-UF) were manufactured as reference samples. The physical and mechanical properties and formaldehyde emissions were evaluated according to international standards. The superficial morphology of the particleboards was studied through optical microscopy (OP) and scanning electron microscopy (SEM). The novel particleboards showed high resistance to moisture, low thickness swelling and a high internal bond strength, when compared with particleboards manufactured with the radiata pine wood particleboards bonded with PU and UF. Flexural properties in the new particleboards were slightly lower than the flexural properties of the reference samples RP-PU and RP-UF, since the distribution and geometry of the particles were different. The results of this research validate the use of P. radiata D. DON cones and E. globulus capsules, bonded with a bio-based polyurethane adhesive, for the manufacture of novel particleboards. This research opens the possibility of an alternative use for the pine cones and Eucalyptus capsules as a new prime source for the manufacture of particleboards and other composite materials.
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    STUDY OF WOOD ADHESIVES ON THE BONDING PROPERTIES IN SOLID AND HOLLOW GLULAM BEAMS OF PINUS RADIATA
    (2022) Nunez-Decap, Mario; Perez-Soto, Gustavo; Opazo-Vega, Alexander; Moya-Rojas, Boris; Vidal-Vega, Marcela
    The aim of this research was study of polyurethane (PUR), isocyanate polymer emulsions (EPI) and melamine-urea-formaldehyde (MUF) adhesives, on the bonding properties of solid and hollow glulam beams of Pinus radiata. The thermomechanical analysis (DMA) of the adhesives was carried out to evaluate their stiffness and reactivity. Glulam beams were evaluated by a bending test. The quality of the bonding was evaluated by resistance to shear and delamination. The morphology of the bonding was studied by microscopy. The DMA study showed that the MUF adhesive had the highest level of stiffness and reactivity. The results of the bending test showed that the highest modulus of rupture results were obtained in solid and hollow laminated beams with MUF adhesive, achieving increases of 30% over the PUR adhesive. The lowest delamination results were obtained in solid glulam beams with MUF and EPI adhesives, while the highest results were 32% and 47% for the PUR adhesive. Finally, glulam beams manufactured with MUF adhesive presented the best performance and results.
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    SYNTHESIS AND WOUND HEALING PROPERTIES OF POLYVINYL ALCOHOL FILMS DOPED WITH METAL NANOPARTICLES OF Cu AND Ag
    (2022) Cardenas-Trivino, Galo; Linares-Bermudez, Nelson; Vergara-Gonzalez, Luis; Cabello-Guzman, Gerardo; Ojeda-Oyarzun, Javier; Nunez-Decap, Mario; Arrue-Munoz, Ramon
    The skin recovery (wound healing) properties of materials based on polyvinyl alcohol (PVA) doped with metal nanoparticles (PVA-MNPs) and their chemical and physical characterization is reported. The synthesis of copper and silver metal nanoparticles supported in PVA was performed by Solvated Metal Atom Dispersed (SMAD) method using 2-ethoxyethanol as solvent. The average size of metal nanoclusters (PVA-Cu = 77 nm, PVA-Ag = 72 nm) was determined by TEM and the distribution of the inorganic phase in the hybrid material was analyzed by SEM-EDX. TGA performed in synthetic air atmosphere shows an improvement in the thermal stability by addition of nanometals to pure polymer, with the copper composite showing a higher thermo resistive capacity than the rest. Antibacterial activity against ATCC bacterial strains of Escherichia coli (E.C.), Staphylococcus aureus (S.A.), Staphylococcus epidermidis (S.E.) and Pseudomonas aeruginosa (P.A.) was determined. The silver compound showed antibacterial activity against all tested microorganisms, while the copper compound was active against S.E. Toxicological and wound healing tests were performed in Sprague Dawley rats with infested injuries on the back which were treated with PVA films doped with copper and silver. The recovery of injures infested with S. aureus is reported. This type of material could be used for biomedical applications, such as skin recovery processes in infected wounds or type I and II burns.
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    Use of Carbon and Basalt Fibers with Adhesives to Improve Physical and Mechanical Properties of Laminated Veneer Lumber
    (2023) Nunez-Decap, Mario; Sandoval-Valderrama, Barbara; Opazo-Carlsson, Camila; Moya-Rojas, Boris; Vidal-Vega, Marcela; Opazo-Vega, Alexander
    Climate change is one of the main factors influencing the research of environmentally friendly materials. This is why the use of engineering fibers as a reinforcement technique in wood, in order to increase its mechanical properties, has recently been investigated. This research presents the results obtained from the use of carbon and basalt fiber fabrics as a reinforcement for microlaminated Radiata Pine wood panels at a laboratory scale using the adhesives epoxy resin and polyvinyl acetate. Tests were carried out in comparison to the control boards, relating the physical properties obtained in terms of thickness swelling by 48 h-water immersion with a decrease of 19% for the polyvinyl acetate and carbon fiber matrix reinforcement, about the mechanical properties evaluated, a better performance was obtained for the epoxy resin and carbon fiber matrix reinforcement and in terms of flexural stiffness and strength (in flatwise), tensile strength and Janka hardness, with an increment of 31%, 38%, 56% and 41%, respectively.
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    Use of Carbon and Basalt Fibers with Adhesives to Improve Physical and Mechanical Properties of Plywood
    (2022) Nunez-Decap, Mario; Barra-Rodriguez, Yasna; Opazo-Carlsson, Camila; Moya-Rojas, Boris; Vidal-Vega, Marcela; Opazo-Vega, Alexander
    Currently, wood is presented as an alternative to traditional building materials and to mitigate climate change. Chile is one of the eight largest wood producers in the world; therefore, wood-based products are an easily accessible resource. The aim of this research is to reinforce at laboratory scale plywood panels with basalt and carbon engineer fibers using epoxy resin and polyvinyl acetate as an adhesive system to improve their physical and mechanical properties. Three-point static bending and Janka hardness tests were carried out. The results showed a better performance in the reinforced boards, which showed an increase in Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) properties in the parallel direction of about 48.2% and 52.8%, respectively. Additionally, for the perpendicular direction, there was an increase of 52.0% and 102.9%, respectively. On the other hand, the Fiber Reinforced Polymer (FRP) plywood panels showed an increase of at least 37% on the Janka hardness property, obtaining higher results with the polyvinyl acetate (PVA) adhesive. Finally, FRP-plywood, PVA-BF and PVA-CF may be a new option for composite wood materials, with their ductile behavior and superior mechanical properties, especially in the perpendicular direction, where the increases were greater than those shown in unreinforced plywood.