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Water-based polyurethane dispersions: chemistry, technology and applications

Over the past few decades, polyurethane-polyurea aqueous dispersions (PUDs) have developed a solid reputation for high performance applications, particularly in the field of adhesives and coatings. PUDs are mostly environmentally compatible products; they are totally devoid or contain only low amounts of volatile organic compounds (VOC). This is an important feature in view of the present environmental policies...

NEWALK: novos materiais e componentes para calçado do futuro

A indústria do calçado é o núcleo de um importante cluster da economia nacional. A sua evolução refletiu-se no aumento da produtividade e no valor bruto da produção. Como resultado, o preço do calçado exportado em 2011 subiu para os 23,70 euros/par, tendo o valor global das exportações atingido 1548 milhões de euros (APICCAPS, 2012). Atualmente, este setor procura afirmar-se em nichos de mercado com maior exigê...

Production of chitosan based films enriched with oregano essential oil for incr...

During the last years, there has been an increasing interest in developing bio-based active films to improve food safety, extend food shelf life and reduce the use of chemical preservatives. Chitosan, a deacetylated derivative of chitin, is a linear polysaccharide consisting of -(1 4) glucosamine and N-acetylglucosamine residues with potential to be used as a food packaging/coating material. This biopolymer can...

alpha-Tocopherol microencapsulation using chitosan and alginate: swelling behav...

Vitamin E is known for its antioxidant activity, particularly for its effective protection against lipid oxidation. Currently, the intake of this important class of bioactive compounds is associated with health benefits. Moreover, due to its antioxidant capacity, vitamin E is frequently added to several foods in order to extend shelf life, mainly by inhibiting lipid oxidation. Vitamin E comprises a set of eight...

α-tocopherol microencapsulation using chitosan and alginate: swelling behaviour...

Vitamin E is known for its antioxidant activity, particularly for its effective protection against lipid oxidation. Currently, the intake of this important class of bioactive compounds is associated with health benefits. Moreover, due to its antioxidant capacity, vitamin E is frequently added to several foods in order to extend shelf life, mainly by inhibiting lipid oxidation. Vitamin E comprises a set of eight...

α-Tocopherol microencapsulation using chitosan and alginate: swelling behaviour...

Chitosan-based leather functional coatings with improved antimicrobial properties

Among the interesting biological activities that have been ascribed to chitosan, the antimicrobial activity is probably the one that generates the higher number of applications. Developing antimicrobial coatings for footwear components to be used in direct contact with the feet is of great interest; both at industrial level (reducing the possibility of material deterioration and quality loss) and from the consu...

Solvent-free aqueous polyurethane dispersions

The industrial production of aqueous polyurethane dispersions (PUDs) is nowadays a well established technology. There are two main synthetic routes to produce PUDs: the acetone process (a former process developed by Bayer AG) and the pre-polymer process (developed as an alternative response to the patented acetone process). Comparatively to the acetone process, the pre-polymer process has one major advantage si...

Solvent-free aqueous polyurethane dispersions

The industrial production of aqueous polyurethane dispersions (PUDs) is nowadays a well established technology. There are two main synthetic routes to produce PUDs: the acetone process (a former process developed by Bayer AG) and the pre-polymer process (developed as an alternative response to the patented acetone process). Comparatively to the acetone process, the pre-polymer process has one major advantage si...

Fungal degradation of lignin-based rigid polyurethane foams

The environmental impacts arising from the use of polymeric materials is a serious problem since they can present long periods of degradation and hence being accumulated in the environment. Polyurethanes (PU) are considered as one of the most versatile polymeric materials offering a wide range of products with applications in diverse sectors. Rigid polyurethane (RPU) foams, due to its excellent insulation and m...