RT info:eu-repo/semantics/article T1 Low density nanocellular polymers based on PMMA produced by gas dissolution foaming: Fabrication and cellular structure characterization A1 Martín de León, Judit A1 Bernardo García, Victoria A1 Rodríguez Pérez, Miguel Ángel K1 Nanocellular polymers K1 Polímeros nanocelulares K1 Nanocellular foams K1 Espumas nanocelulares K1 Polymethylmethacrylate K1 Polimetilmetacrilato AB This paper describes the processing conditions needed to produce low density nanocellularpolymers based on polymethylmethacrylate (PMMA) with relative densities between 0.45 and 0.25,cell sizes between 200 and 250 nm and cell densities higher than 1014 cells/cm3. To produce thesenanocellular polymers, the foaming parameters of the gas dissolution foaming technique using CO2as blowing agent have been optimized. Taking into account previous works, the amount of CO2uptake was maintained constant (31% by weight) for all the materials. Foaming parameters weremodified between 40 C and 110 C for the foaming temperature and from 1 to 5 min for the foamingtime. Foaming temperatures in the range of 80 to 100 C and foaming times of 2 min allow forproduction of nanocellular polymers with relative densities as low as 0.25. Cellular structure hasbeen studied in-depth to obtain the processing-cellular structure relationship. In addition, it hasbeen proved that the glass transition temperature depends on the cellular structure. This effect isassociated with a confinement of the polymer in the cell walls, and is one of the key reasons for theimproved properties of nanocellular polymers. PB MDPI SN 2073-4360 YR 2016 FD 2016 LK http://uvadoc.uva.es/handle/10324/25887 UL http://uvadoc.uva.es/handle/10324/25887 LA eng NO Polymers, 2016, vol. 8, n. 9. 16 p. NO Producción Científica DS UVaDOC RD 27-dic-2024