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Increasing cell homogeneity of semicrystalline, biodegradable polymer foams with a narrow processing window via rapid quenching
Author(s) -
Wright Zachary C.,
Frank Curtis W.
Publication year - 2014
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.23847
Subject(s) - materials science , blowing agent , crystallinity , polymer , composite material , coalescence (physics) , crystallization , quenching (fluorescence) , chemical engineering , polyurethane , physics , quantum mechanics , astrobiology , engineering , fluorescence
Biodegradable polymer foams have the potential to lessen environmental burdens caused by traditional petroleum‐based plastics. One such family of alternatives, poly(hydroxyalkanoates), have tremendous potential in this regard, but have poor foamability owing to a narrow thermal processing window. Of particular interest for this study is poly(hydroxybutyrate‐ co ‐valerate) (PHBV). Two chemical blowing agents were tested for their ability to create low density, closed‐cell PHBV foams, and it is shown here that sodium bicarbonate decreases the bulk density compared to azodicarbonamide blowing agents but with the loss of a closed‐cell structure. To counter this, PHBV foams were quenched with water, leading to faster crystalline formation in the polymer matrix. As a result of faster solidification, a more uniform, closed‐cell bubble morphology was entrapped in the final foam product, leading to high‐expansion ratio foam. Thus, PHBV, a material with poor melt strength, has enhanced melt properties for foaming applications when crystallization is induced on the same time scale as cell coalescence. POLYM. ENG. SCI., 54:2877–2886, 2014. © 2014 Society of Plastics Engineers