Author
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Shogren, Randal |
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Submitted to: Annual Meeting of the Bio Environmentally Degradable Polymer Society
Publication Type: Abstract Only Publication Acceptance Date: 9/26/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: There is considerable current interest in biodegradable polymer coatings/laminates for water sensitive materials such as paper and starch films. Although some water vapor permeability data exist, they have often been measured under different conditions and are thus difficult to compare. As part of an ongoing program to develop water resistant coatings for starch based materials, we present a comparison of the water vapor permeabilities of several biodegradable polymers and how these relate to polymer structure. Water vapor transmission rates (WVTR) were measured using a relative humidity gradient of 100 to 0% and were normalized to a film thickness of 25 um. Values of WVTR (g/m2/d) at 25 deg C were: poly(Beta-hydroxybutyrate-co-12% hydroxyvalerate), 21; poly(L-lactic acid), 170; poly(Epsilon-caprolactone), 190; Bionolle, 340; cellulose acetate propionate, 1720; cellulose acetate, 2800. Values of WVTR were positively correlated with higher polymer solubility parameters, lower crystallinities and lower glass transition temperatures. Although the WVTR of biodegradable polymers are much higher than good barrier materials such as low density polyethylene (1 g/m2/d), they are sufficient for short term (hours to days) protection of starch based materials against water. |
