Instituto Politécnico de Viseu
Repositório Científico
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Cardanol-based adhesive with reduced formaldehyde emission to produce particleboards with waste from bean crops
Publication . Faria, Douglas Lamounier; Scatolino, Mário Vanoli; Oliveira, Juliano Elvis de; Gonçalves, Fabricio Gomes; Soriano, Julio; Protásio, Thiago de Paula; Lelis, Roberto Carlos Costa; Carvalho, Luisa; Mendes, Lourival Marin; Guimarães Junior, José Benedito
Free formaldehyde is a carcinogen whose emission reduction in particleboard has been studied recently to mitigate this environmental and human health problem. One alternative to reduce the emission of formaldehyde in particleboards is by using adhesives produced from natural sources. Cardanol-formaldehyde is an environmentally friendly adhesive made with cashew nut liquid, a byproduct from the cashew chain. This work aimed to produce particleboard using cardanol-formaldehyde in place of urea. In addition, different proportions of bean straw wastes were used to replace pine wood. The combination of eco-friendly adhesive and lignocellulosic waste particles could result in a product that meets market demands while being environmentally nonaggressive. Cardanol-formaldehyde promoted a higher modulus of elasticity (MOE) (1172 MPa) and modulus of rupture (MOR) (4.39 MPa) about panels glued with urea–formaldehyde, which presented a MOE of 764 MPa and MOR of 2.45 MPa. Furthermore, the cardanol-formaldehyde adhesive promoted a 93% reduction in formaldehyde emission, with a reduction from 16.76 to 1.09 mg/100 g oven-dry board for particleboards produced with cardanol-formaldehyde, indicating potential as an adhesive in the particleboard industry.
The Potential of Visible Spectroscopy as a Tool for the In-Line Monitoring of Lignin Methylolation
Publication . Gonçalves, Sofia; Martins, Jorge Manuel; Paiva, Nádia T.; Paiva, Diana; Carvalho, Luisa; Magalhães, Fernão D.
Out of the 50 to 70 million tons of lignin that are produced annually, only 1 to 2% are used for value-added products. Currently, 90% of the total market of this compound corresponds to lignosulphonates (LS). The most successful industrial attempts to use lignin for wood adhesives rely on using it as a partial substitute in phenol–formaldehyde or urea–formaldehyde resins. However, lignin’s aromatic ring presents a low number of reactive sites. Several methods have been proposed to improve its reactivity, such as prior methylolation with formaldehyde. Off-line methods are commonly applied to monitor this reaction’s progress, but this introduces a significant delay in the analysis. This study proposes a new method for in-line monitoring of the methylolation reaction using visible spectroscopy. In order to monitor the reaction progress, principal component analysis was applied to the spectra, and the obtained scores were analyzed. When these results were plotted against those obtained by the off-line methods, a satisfactory regression was obtained at 50 ◦C (R 2 = 0.97) and 60 ◦C (R 2 = 0.98) for two different LS samples. Therefore, it was concluded that visible spectroscopy is a promising technique for studying lignin methylolation.
Water resistance evaluation of a MFU resins with different molar ratio catalyzed with citric acid
Publication . Santos, J.; Pereira, J.; Paiva, N.; Ferra, J.; Magalhães, F.D.; Martins, Jorge Manuel; Carvalho, Luisa
Urea, in either solid form or in solution, is an additive commonly used to control the viscosity or act as a scavenger in MF (melamine-formaldehyde) and MUF (melamine-urea-formaldehyde) resins for particleboard production. The aim of this work was to evaluate the influence of adding urea to MF (melamine-formaldehyde) resin in terms of the water-resistance of the final particleboards. FTIR-ATR spectroscopy, adhesive bonding evaluation system (ABES) and gravimetric techniques were used. MF and MFU (melamine-formaldehyde-urea) resins were prepared. Urea was introduced as an additive, in different percentages (0, 10, 20, and 30% (on adhesive, dry basis), and citric acid was used as catalyst. Beech veneer strips were bonded together with these formulations and then tested in dry conditions and after immersion in water for 24 h. The effect of urea load on the resin curing reaction in dry and humid joints was studied. Particleboards were produced with MF and MFU (melamine formaldehyde urea) resins with different urea loads and using industrial recycled wood particles as raw material. Particleboard evaluation indicated that the water resistance of the final particleboards decreased linearly with urea addition
Formulation and Characterization of a Composite Coating Formulation Based on Acrylic Foam and Cork Granules
Publication . Monteiro, Sandra; Ferreira, Nuno; Paiva, Diana; Silva, Susana P.; Martins, Jorge; Carvalho, Luisa; Magalhães, Fernão D.
Cork, the bark of Quercus suber L., in addition to presenting several notable physicalmechanical properties, possesses a distinctive look and feel that make it attractive for interior surfaces, such as in furniture, wall paneling, or flooring. This work envisaged the development of a coating based on cork granules, a subproduct from the wine stopper industry, capable of creating a smooth surface similar to natural cork. In order to avoid the high rugosity that characterizes surfaces coated with paints that incorporate cork granules, a new solution was developed, based on a foamed acrylic binder, applied by knife coating. The foam formulation was successfully optimized, using appropriate additives and resorting to mechanical agitation to promote the generation of air bubbles. The addition of cork granules did not hinder foam stability, and the final coating displayed the intended visual and sensory characteristics. Dynamic Mechanical Analysis was performed on the pristine acrylic foam and on the composite foam showed a stiffening effect associated with the presence of cork granules, and a thermal transition centered at around −10 ◦C, associated with the acrylic binder’s glass transition. The surface has hardness slightly lower than cork, depending on the amount of particles incorporated. Pull-off testing consistently resulted in substrate failure, indicating that the coating’s cohesion and adhesion are excellent. The developed coating showed to have the intended functionality while being easily applicable on flat panel surfaces. The fact that a foam is used as a binder system allows for a smooth and soft surface, having excellent opacity with minimal usage of cork.
Unidentified paediatric palliative needs: use of the Paediatric Palliative Screening Scale
Publication . Preto, Catarina Sofia Rodrigues; PEREIRA CONDEÇO, LUÍS MIGUEL
Background: Paediatric palliative care should be provided to children and adolescents with complex chronic, life-limiting or life-threatening conditions, from the time of diagnosis, throughout the life course and beyond death, ensuring continuity of care. Aims: To identify children and adolescents with complex chronic conditions at a Portuguese healthcare unit who may be eligible for referral to paediatric palliative care. Methods: An exploratory, descriptive quantitative and cross-sectional study was conducted, using the Portuguese version of the Paediatric Palliative Screening Scale. A total of 397 children and adolescents attending a paediatric developmental consultation were included in the study. Of these, 10 participants met the study’s inclusion criteria and were assessed through telephone interviews with their parents. Findings: The use of the screening tool enabled the identification of two participants (20%) who would benefit from referral. Conclusions: Integrating systematic tools, such as the Paediatric Palliative Screening Scale, into routine consultations may enable earlier referral to palliative care, improving quality of care and support for families. Implications for practice: Routine use of referral tools combined with improved palliative care literacy and communication may facilitate earlier identification of children with palliative care needs and more timely referral to specialist services. Future development of more holistic referral tools that incorporate functional, psychosocial and symptom-related needs could support more equitable, person-centred paediatric palliative care.