Susan Selke | Michigan State University (original) (raw)

Papers by Susan Selke

Macromolecular Bioscience, 2007

Journal of The Science of Food and Agriculture, 2006

Poly(lactide) (PLA) polymers have garnered increased attention in the last few years as food pack... more Poly(lactide) (PLA) polymers have garnered increased attention in the last few years as food packaging materials because they are environmentally friendly polymers. As the production of PLA increases and price per pound drops, PLA is becoming a growing alternative as a green food packaging material. In this research, the organic vapor barrier properties of commercially available PLA polymers were studied. Gravimetric sorption tests in PLA films were carried out, and the diffusion (D), solubility (S) and permeability (P) coefficients for ethyl acetate and d-limonene in PLA were determined. For ethyl acetate, values of P = 1.22 × 10−17 kg m m−2 s−1 Pa−1, D = 2.63 × 10−15 m2 s−1, and S = 4.62 × 10−3 kg m−3 Pa−1) at 45 °C and a partial pressure of 12 654 Pa were obtained. For d-limonene, no trace was detected after 21 days of testing at 45 °C and 258 Pa, which indicates a permeability coefficient lower than 9.96 × 10−21 kg m m−2 s−1 Pa−1. Poly(lactide) polymers demonstrated good aroma barrier to ethyl acetate and d-limonene, and will most likely be good aroma barriers. PLA is not likely to promote flavor loss by either permeation or scalping. Copyright © 2005 Society of Chemical Industry

Journal of Plastic Film & Sheeting, 2003

ABSTRACT: High molecular mass poly(lactide), (PLA), is an attractive polymer family because in ad... more ABSTRACT: High molecular mass poly(lactide), (PLA), is an attractive polymer family because in addition to being thermoplastic, biodegradable, compostable, and produced from annually renewable resources, it shows mechanical and barrier behavior comparable to synthetic ...

15 POLY (LACTIC ACID)/STARCH BLENDS LONG YU, EUSTATHIOS PETINAKIS, KATHERINE DEAN, AND HONGSHEN L... more 15 POLY (LACTIC ACID)/STARCH BLENDS LONG YU, EUSTATHIOS PETINAKIS, KATHERINE DEAN, AND HONGSHEN LIU 15.1 INTRODUCTION A special ... D. Dieterich, E. Grigat, W. Hahn, in: G. Oertel (Ed.), Polyure-thane Handbook: Chemistry, Raw Materials, Processing ...

Polymer Degradation and Stability, 2010

Poly(lactide), PLA, films, which are both produced from renewable resources and compostable, are ... more Poly(lactide), PLA, films, which are both produced from renewable resources and compostable, are increasingly of interest in a variety of applications including packaging. PLA has high gloss and clarity along with good mechanical, physical, and barrier properties. ...

Macromolecular Bioscience, 2004

ABSTRACT Poly(L-lactic acid) (PLLA)/starch blends with various concentrations of two natural anti... more ABSTRACT Poly(L-lactic acid) (PLLA)/starch blends with various concentrations of two natural antioxidants, α-tocopherol (α-TOC) and resveratrol, were fabricated by a melt blending and compression molding processes. The effects of the two antioxidants on the optical (color), thermal and mechanical properties of PLLA/starch blends with antioxidants were assessed. PLLA/starch blend films with α-TOC and resveratrol showed a yellowish color influenced by the combined effect of white starch and the brown color of the antioxidants. The glass transition and melting temperatures were significantly reduced with the addition of antioxidants while enhanced thermal stability was observed, which could be a benefit and important for processing and production. The enhanced mechanical properties could be attributed to not only a compatibilization effect based on the chemical linkage between PLLA and starch chains, but also restriction of the chain mobility by antioxidants. The release of resveratrol from PLLA and PLLA/starch blend films into ethanol followed Fickian behavior. The D values of α-TOC were in the range of 0.47–3.95 × 10−11 cm2 s−1 for PLLA films and 0.70–6.83 × 10−11 cm2 s−1 for PLLA/starch blend films at 13 °C, 5.67–13.0 × 10−11 cm2 s−1 for PLLA films and 4.10–24.2 × 10−11 cm2 s−1 for PLLA/starch blend films at 23 °C, and 89.0–118.0 × 10−11 cm2 s−1 for PLLA films and 123–282 × 10−11 cm2 s−1 for PLLA/starch blend films at 43 °C. The D values of resveratrol were in the range of 0.073–0.54 × 10−10 cm2 s−1 for PLLA films and 1.42–6.93 × 10−10 cm2 s−1 for PLLA/starch blend films at 13 °C, 0.90–3.44 × 10−10 cm2 s−1 for PLLA films and 4.16–22.3 × 10−10 cm2 s−1 for PLLA/starch blend films at 23 °C, and 24.8–74.1 × 10−10 cm2 s−1 for PLLA films and 40.1–309 × 10−10 cm2 s−1 for PLLA/starch blend films at 43 °C.

Environmental Science & Technology, 2015

Biodegradation-promoting additives for polymers are increasingly being used around the world with... more Biodegradation-promoting additives for polymers are increasingly being used around the world with the claim that they effectively render commercial polymers biodegradable. However, there is a lot of uncertainty about their effectiveness in degrading polymers in different environments. In this study, we evaluated the effect of biodegradation-promoting additives on the biodegradation of polyethylene (PE) and polyethylene terephthalate (PET). Biodegradation was evaluated in compost, anaerobic digestion, and soil burial environments. None of the five different additives tested significantly increased biodegradation in any of these environments. Thus, no evidence was found that these additives promote and/or enhance biodegradation of PE or PET polymers. So, anaerobic and aerobic biodegradation are not recommended as feasible disposal routes for non-biodegradable plastics containing any of the five tested biodegradation-promoting additives.

Journal of Applied Polymer Science, 2004

The aim of this work was to study the variations in the oxygen diffusion, solubility, and permeab... more The aim of this work was to study the variations in the oxygen diffusion, solubility, and permeability coefficients of polylactide (PLA) films at different temperatures (5, 23, and 40°C) and water activities (0–0.9). The results were compared with the oxygen diffusion, solubility, and permeability coefficients obtained for poly(ethylene terephthalate) (PET) films under the same experimental conditions. The water sorption isotherm for PLA films was also determined. Diffusion coefficients were determined with the half-sorption time method. Also, a consistency test for continuous-flow permeability experimental data was run to obtain the diffusion coefficient with the lowest experimental error and to confirm that oxygen underwent Fickian diffusion in the PLA films. The permeability coefficients were obtained from steady-state permeability experiments. The results indicated that the PLA films absorbed very low amounts of water, and no significant variation of the absorbed water with the temperature was found. The oxygen permeability coefficients obtained for PLA films (2–12 × 10−18 kg m/m2 s Pa) were higher than those obtained for PET films (1–6 × 10−19 kg m/m2 s Pa) at different temperatures and water activities. Moreover, the permeability coefficients for PLA and PET films did not change significantly with changes in the water activity at temperatures lower than 23°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1790–1803, 2004

Energy in Agriculture, 1983

Journal of applied polymer science, Jan 1, 2004

... 2 Water 91 7.8 Pharmacological Transport 93 7.9 Summary 93 References 94 8 Optical Properties... more ... 2 Water 91 7.8 Pharmacological Transport 93 7.9 Summary 93 References 94 8 Optical Properties 97 Carla MB Goncalves, Joao AP Coutinho ... of PLA in Blends 409 23.5 Conclusions 410 References 410 24 Photodegradation and Radiation Degradation 413 Wataru Sakai and ...

Macromolecular …, Jan 1, 2007

Polymer Degradation …, Jan 1, 2010

The biodegradation and hydrolysis rates of an aliphatic aromatic copolyester were measured in man... more The biodegradation and hydrolysis rates of an aliphatic aromatic copolyester were measured in manure, food, and yard compost environments and in phosphate buffer solution (pH = 8.0) and vermiculite at 58 °C. Mineralization, molecular weight reduction, and structural changes determined by DSC, FTIR, and 1H NMR were used as indicators of the biodegradation and hydrolysis rates. Poly(butylene adipate-co-terephthalate), PBAT, film biodegraded at distinctive rates in manure, food, and yard compost environments having different microbial activities. The highest biodegradation rate was found in manure compost, which had the highest CO2 emissions and lowest C/N ratio. The possible presence of extracellular enzymes in manure and food composts may facilitate the hydrolytic reaction since greater molecular weight reduction rates were observed in these composts. 1H NMR and thermal analysis revealed that, while PBAT is a semi-crystalline copolyester with cocrystallization of BT and BA dimers, the soft aliphatic domain (BA) and the amorphous region are more susceptible to hydrolysis and biodegradation than the rigid aromatic domain (BT) and the crystalline region.

Journal of plastic film and …, Jan 1, 2003

Journal of Applied Polymer …, Jan 1, 2010

Poly(lactic acid), PLA, composites containing 0, 1, 3, and 5 wt % zeolite type 4A were prepared u... more Poly(lactic acid), PLA, composites containing 0, 1, 3, and 5 wt % zeolite type 4A were prepared using extrusion/injection compounding techniques. Morphological characterizations were carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Physical properties were evaluated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) and mechanical properties by standard tensile testing. The morphological studies showed a homogenous dispersion of zeolite particles within the PLA matrix. As the fracture stress propagated, zeolite particles remained embedded into the matrix, indicating the existence of good interfacial adhesion between zeolite particles and the PLA matrix. The improvement in the interfacial adhesion was also confirmed by applying Nicolais-Narkis and Pukanszky models. The percent crystallinity of the PLA and the temperature- dependant elastic and viscous modulus of the composite increased with the proportion of zeolites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Macromolecular Bioscience, Jan 1, 2004