INIFTA   05425
INSTITUTO DE INVESTIGACIONES FISICO-QUIMICAS TEORICAS Y APLICADAS
Unidad Ejecutora - UE
artículos
Título:
Phase separation kinetics in hybrids acrylic/polyurethane
Autor/es:
PERUZZO, P.J.; PARDINI, O.R.; AMALVY, J.I.
Revista:
Activity Report 2006 – Brazilian Synchrotron Light Laboratory
Referencias:
Año: 2007 p. 1 - 2
ISSN:
1518-0204
Resumen:
also know as poly(urethane-acrylate)copolymers are an interesting class of materials that combine film-forming properties of polyurethanes (PUs) and the low prices of acrylics (ACs). They can be used in the production of environmentally friendly lacquers and special binding materials used in the ceramics process. The incorporation of acrylic monomers lead to cost reduction but properties are affected depending on the amount and on the way of incorporation. The incompatibility of both polymers leads to phase segregation and as a consequence a domain structure is formed. However, the presence of a chemical linkage between the PU and the acrylics restricts the phase structure to the nanoscale, i.e. on the order of the 10-20 nm. For these reasons this type of materials are also known as nanopolymers and the phase structure is directly responsible for the mechanical properties. However the amount of incorporation of acrylic into a PU matrix is limited and, for high acrylic contents, multiphase segregation can occurs and a domain of pure acrylic polymer is formed. As observed in previous work films formed from dispersions with a 90 wt% of acrylic are phase separated. During our characterization of hybrids acrylic/polyurethanes films we have found that a thermal treatment or curing, leads to films with better mechanical and chemical properties and also lower water absorption. However by annealing at 60ºC for 48 h a greater tendency to form separated phases was observed. For instance a system with acrylic content of 70 wt% shows phase separation after annealing 48 h at 60ºC, showing the thermodynamic incompatibility of both types of polymers. In a phase separated system the mechanical properties and applications are expected to be limited due to the inhomogeneities in the material. In order to follow the structural changes occurring during the annealing or thermal treatment, we proposed in this work to study the kinetics of phase segregation of a hybrid acrylic/polyurethane with 70 wt% of acrylic component using SAXS and WAXS techniques. nm. For these reasons this type of materials are also known as nanopolymers and the phase structure is directly responsible for the mechanical properties. However the amount of incorporation of acrylic into a PU matrix is limited and, for high acrylic contents, multiphase segregation can occurs and a domain of pure acrylic polymer is formed. As observed in previous work films formed from dispersions with a 90 wt% of acrylic are phase separated. During our characterization of hybrids acrylic/polyurethanes films we have found that a thermal treatment or curing, leads to films with better mechanical and chemical properties and also lower water absorption. However by annealing at 60ºC for 48 h a greater tendency to form separated phases was observed. For instance a system with acrylic content of 70 wt% shows phase separation after annealing 48 h at 60ºC, showing the thermodynamic incompatibility of both types of polymers. In a phase separated system the mechanical properties and applications are expected to be limited due to the inhomogeneities in the material. In order to follow the structural changes occurring during the annealing or thermal treatment, we proposed in this work to study the kinetics of phase segregation of a hybrid acrylic/polyurethane with 70 wt% of acrylic component using SAXS and WAXS techniques.