Xu JK, Zhang L, Li DL, Bao JB, Wang ZB. Foaming of Poly(3-hydroxybutyrate-
co-3-hydroxyvalerate) with Supercritical Carbon Dioxide: Foaming Performance and Crystallization Behavior.
ACS OMEGA 2020;
5:9839-9845. [PMID:
32391471 PMCID:
PMC7203685 DOI:
10.1021/acsomega.9b04501]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 04/13/2020] [Indexed: 05/12/2023]
Abstract
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) samples were successfully foamed using supercritical carbon dioxide as a physical foaming agent. PHBV sheets were first saturated at 175 °C followed by a foaming process at different temperatures (145 to 165 °C) and different CO2 pressures (10 to 29 MPa). It was found that microcellular structures with average cell sizes ranging from 6 to 22 μm and cell densities ranging from 108 to 1.2 × 109 cells/cm3 could be controllably prepared by selecting suitable foaming conditions. To investigate crystallization behavior during the foaming process and explore the corresponding foaming mechanism, differential scanning calorimetry, wide angle X-ray diffraction, and small-angle X-ray scattering characterizations were carried out. Stretching behavior during the cell growth stage may increase the crystal nucleation rate, and the generated crystal nucleus accelerates the crystallization rate as well as thickens PHBV crystal lamellae.
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