Selected Morphological and Functional Properties of Extruded Acetylated Starch-Polylactic Acid Foams
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- 作者：Junjie Guan and Milford A. Hanna
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2005
- 出版时间：April 27, 2005
- 年：2005
- 卷：44
- 期：9
- 页码：3106 - 3115
- 全文大小：675K
- 年卷期：v.44,no.9(April 27, 2005)
- ISSN：1520-5045
文摘
Native starch and polylactic acid (PLA) are biodegradable polymers that can be used in packagingmaterials. Their hydrophilic properties hinder their widespread use. Hydrophobicity can beimproved significantly by acetylating native starch. This study was conducted to determine themorphological and functional properties of acetylated starch-PLA foams. Acetylated corn starch,with a degree of substitution (DS) of 2.3, and acetylated potato starch, with a DS of 1.07, wereextruded with 5, 10, or 15% PLA in a twin screw co-rotating extruder at 150, 160, or 170 
Cbarrel temperatures and 130, 150, or 170 rpm screw speeds. Differential scanning calorimetry(DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were usedto analyze the morphological properties of the extruded foams. A central composite responsesurface design was used to analyze the effects of acetylated starch type, PLA content, barreltemperature, and screw speed on the specific mechanical energy requirements of preparingextruded foams and the radial expansion ratios and compressibilities of the extruded foams.DSC showed that glass transition temperatures (Tg's) and melting temperatures (Tm's) of DS2.3 corn starch-PLA foams were between the Tg's and Tm's of DS 2.3 corn starch and PLA. TheTg's of DS 1.07 potato starch-PLA foams were higher than those of acetylated potato starchand PLA, while the Tm's were closer to that of the PLA, when acetylated potato starch was thepredominant phase in the blends. XRD showed that both acetylated starch and PLA lostcrystallinity during extrusion. The X-ray pattern of the DS 1.07 potato starch-PLA foam wassimilar to those of DS 1.07 potato starch and PLA. FTIR spectroscopy confirmed no new bondswere formed in either DS 2.3 corn starch-PLA or DS 1.07 potato starch acetate-PLA foams.The type of acetylated starch, PLA content, barrel temperature, and screw speed had significanteffects on the specific mechanical energy requirements, radial expansion ratios, and compressibilities of the acetylated starch foams.
Cbarrel temperatures and 130, 150, or 170 rpm screw speeds. Differential scanning calorimetry(DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were usedto analyze the morphological properties of the extruded foams. A central composite responsesurface design was used to analyze the effects of acetylated starch type, PLA content, barreltemperature, and screw speed on the specific mechanical energy requirements of preparingextruded foams and the radial expansion ratios and compressibilities of the extruded foams.DSC showed that glass transition temperatures (Tg's) and melting temperatures (Tm's) of DS2.3 corn starch-PLA foams were between the Tg's and Tm's of DS 2.3 corn starch and PLA. TheTg's of DS 1.07 potato starch-PLA foams were higher than those of acetylated potato starchand PLA, while the Tm's were closer to that of the PLA, when acetylated potato starch was thepredominant phase in the blends. XRD showed that both acetylated starch and PLA lostcrystallinity during extrusion. The X-ray pattern of the DS 1.07 potato starch-PLA foam wassimilar to those of DS 1.07 potato starch and PLA. FTIR spectroscopy confirmed no new bondswere formed in either DS 2.3 corn starch-PLA or DS 1.07 potato starch acetate-PLA foams.The type of acetylated starch, PLA content, barrel temperature, and screw speed had significanteffects on the specific mechanical energy requirements, radial expansion ratios, and compressibilities of the acetylated starch foams.