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- Development of new footwear materials within the extralight safe shoe projectPublication . Fernandes, Isabel P.; Rafael, Helder Martins; Fernandes, Albano M.; Nunes, Bernardo; Pinto, Vera; Ferreira, Maria José; Barreiro, M.F.At present, footwear is considered as one of the most internationalized sectors of the Portuguese industry, having a major importance for the national economy, as it is proved by 2017 economic data: 83.3 billion shoes pairs were exported, representing an average value of 1.96 billion euros. The remarkable progress of the footwear sector is strongly related with the investment in research and technological development made in the last years, along with an attentive surveillance of the market opportunities, which in its turns, allows the identification the latest consumer demands and of new business opportunities. One example of these novel tendencies is the actual society demand for lightweight and comfortable footwear, which prompted the development of ultralight (low-density) materials. Additionally, the evolution of consumers' environmental awareness, allied to the demand for bio-products, is considered a challenge for the footwear sector. Thus, both challenges motivated the development of new materials within the scope of the Extralight Safe Shoe project, namely ultralight microcellular polyurethanes and natural composite-based materials. In this context, the work performed was focused on: (i) the development of ultralight microcellular polyurethanes (PUs) with suitable properties for the production of midsoles for technical footwear, and (ii) the development of lighter and more flexible PU/cork composites for production of insoles.
- Ultralight microcellular polyurethanes for the production of technical footwear componentsPublication . Rafael, Helder Martins; Fernandes, Isabel P.; Gomes, Helder; Pinto, Vera; Fernandes, A.M.; Ferreira, Maria José; Barreiro, M.F.Today's society demands lightweight and comfortable footwear products, which represents a market opportunity for the footwear industry, motivating the development of new low-density (ultralight) materials. This research is dedicated to the development of ultralight microcellular polyurethanes (PUs) with suitable properties for the production of midsoles for technical footwear. In this context, the studies performed in this work aimed at reduce the density of microcellular PUs by the incorporation of additives based on expandable thermoplastic microspheres. Samples of a base formulation were modified by the incorporation of 1, 2 and 3% of the additive. The produced materials result in PUs with densities that varied from 0.45 to 0.30 g/cm3. The performed characterization pointed out for PUs with adequate technical properties, with particular emphasis for impact absorption, which evidenced the suitability of the developed materials for the production of midsoles for ultralight safety shoes.
- Water-borne polyurethane-ureas added with plant extracts with bacteriostatic characteristicsPublication . Santamaria-Echart, Arantzazu; Fernandes, Isabel P.; Barreiro, M.F.; Calvo-Correas, T.; Corcuera, Maria Angeles; Eceiza, ArantaxaThe environmental awareness has promoted the development of new materials towards eco-friendly systems based on both, green synthesis processes and raw-materials of renewable origin. In this way, focusing the synthesis methods, the use of waterborne polyurethane-urea dispersions has gained attention due to their versatility leading to a wide variety of applications [1], broadening the range of applications. In addition, it is worth noting that the dispersibility in water offers the possibility of incorporating water compatible additives, such as plant extracts obtained by aqueous-based extraction procedures. Therefore, in this work bioactive plant extracts from Melissa officinalis L. [2] were incorporated into waterborne polyurethane-urea dispersions (WBPUU), varying their content and using three different incorporation routes. These dispersions were characterized and employed in the preparation of films which were analyzed from the viewpoint of physicochemical, thermal, thermomechanical and mechanical properties as well as their morphology, among others. Finally, the antibacterial properties of the films were analyzed after 1 and 4 days of incubation, where it was observed that the content and incorporation route of the extracts has influenced the behavior of the films against common pathogens (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa).
- Functionalization of yogurts with Agaricus bisporus extracts encapsulated in spray-dried maltodextrin crosslinked with citric acidPublication . Francisco, Cristhian Rafael Lopes; Heleno, Sandrina A.; Fernandes, Isabel P.; Barreira, João C.M.; Calhelha, Ricardo C.; Barros, Lillian; Gonçalves, Odinei Hess; Ferreira, Isabel C.F.R.; Barreiro, M.F.Mushroom extracts contain bioactive compounds potentially useful to functionalize foodstuffs. Herein, alcoholic extracts of Agaricus bisporus were studied for their bioactivity and viability as functional ingredients in a food product with high water content (yogurt). Extracts were microencapsulated (to improve their stability and hydrophilicity) by spray-drying, using maltodextrin crosslinked with citric acid as encapsulating material. The effect of thermal treatment (after atomization) on crosslinking and bioactivity of microspheres was tested. The incorporation of free and thermally untreated forms resulted in yogurts with higher initial antioxidant activity (EC 50 values: 214 and 272 mg.mL −1 ) that decreased after 7 days (EC 50 values: 248 and 314 mg.mL −1 ). Contrarily, thermally treated microencapsulated extracts showed higher antioxidant activity after the same period (EC 50 values, 0 days: 106 mg.mL −1 ; 7 days: 48.7 mg.mL −1 ), in result of an effective protection provided by microencapsulation with crosslinked maltodextrin and citric acid. Functionalized yogurts showed an overall maintenance of nutritional properties.
- Valorization of lignin side-streams into polyols and rigid polyurethane foams—a contribution to the pulp and paper industry biorefineryPublication . Pinto, João A.; Fernandes, Isabel P.; Pinto, Virgínia; Gomes, Elson; Oliveira, Cátia F.; Pinto, Paula C.R.; Mesquita, L.M.R.; Piloto, P.A.G.; Rodrigues, Alírio; Barreiro, M.F.Valorization of industrial low-value side-streams are of great interest, contributing to boosts in the circular economy. In this context, lignin side-streams of the pulp and paper industry were oxypropylated to produce biobased polyols and tested in the synthesis of rigid polyurethane (RPU) foams. E. globulus lignins, namely a lignin isolated from an industrial Kraft black liquor and depolymerized lignins obtained as by-products of an oxidation process, were used. RPU foams, synthesized with 100% lignin-based polyols and using a 1.1 NCO/OH ratio, were characterized concerning apparent density, morphology, thermal conductivity, thermal stability, and heat release rate (HRR). Foams containing the lignin-based polyols presented densities varying from 44.7 to 112.2 kg/m3 and thermal conductivity in the range of 37.2–49.0 mW/mK. For the reference foam (sample produced with 100% wt. Daltofoam TP 32015 polyol), values of 70.9 kg/m3 and 41.1 mW/mK were obtained, respectively. The achieved results point out the viability of using the generated lignin-based polyols at 100% content in RPU foams, mainly when depolymerized lignins are used. Moreover, fire retardancy was favored when the lignin-based polyols were introduced. The proposed strategies can contribute to establishing the integrated pulp and paper biorefinery concept where material synthesis (polyols and RPU foams) can be combined with chemical production (vanillin and syringaldehyde).
- Cork-based composites: studies on binder replacement and incorporation of biomass-derived additivesPublication . Rafael, Helder Martins; Fernandes, Isabel P.; Nunes, Bernardo; Pinto, Vera; Ferreira, Maria José; Barreiro, M.F.; Rafael, Helder MartinsThe Portuguese footwear industry is an important economic sector once it is one of the most active national business areas. The investment made in the production of footwear with high technological performance, and high technical-scientific requirements, evidences the valorization of the footwear industry during the last years. In addition, the evolution of consumers' environmental awareness, allied to the demand for bio-products, is considered a challenge for this sector. Therefore, the development of novel composites, based on natural materials and by adopting green productive processes, represents an area of great interest. In fact, cork, the natural material selected for this application, has properties such as impermeability, good compressibility and resilience, as well as low density, being usually applied in the form of composites for the production of footwear components like shoe insoles and soles. Cork is the bark of a cork oak (Quercus suber L.), which is normally harvested every 9-12 years. Among the corkproducing countries, Portugal has the largest annual production, with around 100.000 tons, which represented 49.6% of the worldwide production in 2016. Traditionally, the cork agglomeration process uses a reactive polyurethane-based adhesive, which results on composites with low flexibility and poor water absorption/desorption characteristics, generating products with low comfort properties. In addition, this adhesive is based on toluene diisocyanate (TDI), which is classified as a high toxic compound, thus motivating its replacement by environmental friendly products. Herein, the use of green adhesives such as water-based polyurethanes dispersions can be envisaged. Furthermore, the low water absorption capacity of the generated composites is related to the hydrophobic character of the cork itself and the used binder, which results in low absorption of the sweat, promoting a sensation of discomfort when footwear incorporating these materials is used. Considering all the above mentioned, the present work is focused on the production of novel cork-based composites, where the traditionally used adhesive was replaced by commercial water-based polyurethane adhesives. In addition, the effect of incorporating residual biomasses on the water absorption/desorption properties will be tested.
- α-Tocopherol microencapsulation using chitosan and alginate: swelling behaviour under different pHPublication . Ribeiro, Andreia; Vieira, Dalila; Fernandes, Isabel P.; Amaral, Joana S.; Barreiro, M.F.Vitamin E is known for its antioxidant activity, particularly for its effective protection against lipid oxidation. The theory that reactive species, such as free radicals, may be involved in the development of degenerative processes associated with aging and cancer has led to a growing interest in the study of most antioxidants. In particular, Vitamin E is considered a lipophilic antioxidant, comprising a set of eight compounds (a-, p-, y-, 8-tocopherols and tocotrienols), of which α-tocopherol is the one presenting the highest capacity of free radicals uptake, in vitro. Due to α -tocopherol instability and sensitivity towards temperature re, oxygen and light, vitamin E supplements are generally administered in the most stable form of α-tocopherol acetate or succinate. However, these forms are considered to have a lower intestinal absorption.
- Scentfashion®: Microencapsulated perfumes for textile applicationPublication . Rodrigues, Sofia Nogueira; Martins, Isabel M.; Fernandes, Isabel P.; Gomes, P.B.; Mata, Vera G.; Barreiro, M.F.; Rodrigues, AlírioThis work is a contribution to the introduction of emergent technologies in the textile sector, namely the microencapsulation of fragrances and its application to obtain added-value products. Interfacial polymerization was used to produce polyurethane/urea (PUU) microcapsules with a perfume for industrial application on textile substrate having in view man suits production. The extent of reaction of PUU microcapsules formation was followed by Fourier transform infrared spectroscopy. Size distribution and morphology of the produced microcapsules were studied using particle size analysis, optical microscopy and scanning electron microscopy. Impregnation on textile substrates was tested both at laboratory level and at industrial scale. The fragrance release from textile substrates was measured with headspace chromatography. The content of microcapsules was released with light abrasion to simulate day-to-day wear, and fabrics impregnated at laboratory scale have survived to 9000 abrasion cycles. Microcapsules have continued to release aroma up to five dry cleaning washing cycles.
- Lipid composition optimization in spray congealing technique and testing with curcumin-loaded microparticlesPublication . Sorita, Guilherme Dallarmi; Santamaria-Echart, Arantzazu; Gozzo, Ângela Maria; Gonçalves, Odinei Hess; Leimann, Fernanda Vitória; Bona, Evandro; Manrique, Yaidelin A.; Fernandes, Isabel P.; Ferreira, Isabel C.F.R.; Barreiro, M.F.Spray-congealing, a technique based on the fast solidification of sprayed molten lipids, is considered a novel strategy to encapsulate natural products. Among others, it is a safe, low cost, fast and reproducible technique, with rising interest for several applications (e.g. food applications). One of the key parameters for the application of this technique is the lipid solidification temperature, which can be modulated by optimizing the lipid composition. In this work, three lipid components (beeswax, carnauba wax, and medium-chain triglycerides (Miglyol 812)) were selected, and the mixture composition modelled using a simplex-centroid experimental design. Three different lipid compositions were chosen to validate the proposed model, then tested in the preparation of curcumin-loaded microparticles (1.5%, w/w). The produced microparticles were analysed in terms of colour, morphology, particle size, encapsulation efficiency and load, physicochemical, crystalline, and thermal properties. Results evidenced that microparticle's properties, including encapsulation efficiency, vary according to the used lipid mixture, supporting their tailoring role. This fact brings advantages in the design of microencapsulation systems based on spray congealing processes, broadening their applicability. Moreover, lipid composition optimisation was proved to be an important tool to precede the development of spray-congealing applications.
- Fungal degradation of lignin-based rigid polyurethane foamsPublication . Amaral, Joana S.; Sepúlveda, Manuel Martinho Vilas Boas; Cateto, Carolina; Fernandes, Isabel P.; Rodrigues, Alírio; Belgacem, Mohamed Naceur; Barreiro, M.F.In this work, the ability of Aspergillus niger to degrade two lignin-based rigid polyurethane (RPU) foams was evaluated and compared with a control RPU foam based on a commercial polyether-polyol, Lupranol 3323. The foams degradation was studied according to different procedures, namely by setting different series of batch cultures, either using liquid media or soil conditions, for 90 days at 30 C. For the soil conditions, two different assays were performed, namely with and without A. niger addition. The changes in the morphology of the RPU foams were evaluated by optical (OM) and scanning electron microscopy (SEM), whereas the structural modifications were inspected by FTIR spectroscopy. After 90 days treatment, morphological changes were clearly visible at the surface (cell wall) of the two lignin-based foams indicating a stronger effect of the microorganisms’ activity in these samples. FTIR spectra confirmed that the chemical structure of the polymer suffered modifications after the respirometry assays due to microorganisms attack. Comparatively to the commercial foam, it was observed that both the lignin-based foams presented a higher degradation level.