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Low Density Nanocellular Polymers Based on PMMA Produced by Gas Dissolution Foaming: Fabrication and Cellular Structure Characterization
Año del Documento
Polymers 2016, 8, 265; doi:10.3390/polym8070265
This paper describes the processing conditions needed to produce low density nanocellular polymers 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 these nanocellular polymers, the foaming parameters of the gas dissolution foaming technique using CO2 as blowing agent have been optimized. Taking into account previous works, the amount of CO2 uptake was maintained constant (31% by weight) for all the materials. Foaming parameters were modified between 40 C and 110 C for the foaming temperature and from 1 to 5 min for the foaming time. Foaming temperatures in the range of 80 to 100 C and foaming times of 2 min allow for production of nanocellular polymers with relative densities as low as 0.25. Cellular structure has been studied in-depth to obtain the processing-cellular structure relationship. In addition, it has been proved that the glass transition temperature depends on the cellular structure. This effect is associated with a confinement of the polymer in the cell walls, and is one of the key reasons for the improved properties of nanocellular polymers.
Revisión por pares
Financial assistance from MINECO and FEDER program (MAT 2012 – 34901) MINECO, FEDER, UE (MAT2015-69234-R) and the Junta de Castile and Leon (VA035U13) are gratefully acknowledged. Financial support from Junta of Castile and Leon grant Q4718001C (J. Martín-de León) and FPU grant FPU14/02050 (V. Bernardo) from the Spanish Ministry of Education is gratefully acknowledged.
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