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Author(s): Mário Rui P. F. N. Costa
Arantzazu Santamaria-Echart
Isabel Fernandes
Ainara Saralegi
Filomena Barreiro
Maria Angeles Corcuera
Arantxa Eceiza
Title: Synthesis of waterborne polyurethane-urea dispersions with chain extension step in homogeneous and heterogeneous media
Issue Date: 2016-05-13
Abstract: Hypothesis: The possibility of tailoring the final properties of environmentally friendly waterbornepolyurethane and polyurethane-urea dispersions and the films they produce makes them attractive fora wide range of applications. Both the reagents content and the synthesis route contribute to theobserved final properties.Experiments: A series of polyurethane-urea and polyurethane aqueous dispersions were synthesizedusing 1,2-ethanediamine and/or 1,4-butanediol as chain extenders. The diamine content was varied from0 to 4.5 wt%. Its addition was carried out either by the classical heterogeneous reaction medium (afterphase inversion step), or else by the alternative homogeneous medium (prior to dispersion formation).Dispersions as well as films prepared from dispersions have been later extensively characterized.Findings: 1,2-Ethanediamine addition in heterogeneous medium leads to dispersions with high particlesizes and broad distributions whereas in homogeneous medium, lower particle sizes and narrow distributions were observed, thus leading to higher uniformity and cohesiveness among particles during film formation. Thereby, stress transfer is favored adding the diamine in a homogeneous medium; and thusthe obtained films presented quite higher stress and modulus values. Furthermore, the higher uniformityof films tends to hinder water molecules transport through the film, resulting, in general, in a lower waterabsorption capacity
Related Information: info:eu-repo/grantAgreement/FCT - Fundação para a Ciência e Tecnologia/Projetos Estratégicos/UID/EQU/50020/2013- POCI-01-0145-FEDER-006984/Laboratório de Processos de Separação e Reação - Laboratório de Catálise e Materiais/LSRE-LCM
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FEUP - Artigo em Revista Científica Internacional

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