Solid State Foaming of Poly(lactic acid) Blown with Compressed CO2: Influences of Long Chain Branching and Induced Crystallization on Foam Expansion and Cell Morphology

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• 作者：Qian Ren ; Jingjing Wang ; Wentao Zhai ; Shengpei Su
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2013
• 出版时间：September 18, 2013
• 年：2013
• 卷：52
• 期：37
• 页码：13411-13421
• 全文大小：818K
• 年卷期：v.52,no.37(September 18, 2013)
• ISSN：1520-5045

文摘

In this study, poly(lactic acid) (PLA) resins with linear (L-PLA) and branched structure (B-PLA) were selected, and the solid state foaming technology was applied to prepare PLA foams. B-PLA foams exhibited a high expansion ratio of about 40 and cell density of 10^5鈥? cells/cm³, whereas L-PLA foams only had the highest expansion ratio of 29.8 and cell density of 10^3鈥? cells/cm³. When PLA resins were induced crystallization during CO₂ saturation, however, the prepared L-PLA foams presented the highest expansion ratio of 37.4 and cell density of 10^6鈥? cells/cm³. The cell structure evolution of PLA foams with the foaming time suggested that the in situ formed crystal domains supplied nucleating sites to enhance cell nucleation and acted as physical cross-linking points to stabilize cell structure. These interesting results demonstrated that the induced crystallization might be more attractive than the chain modification to improve the foaming behavior using solid state foaming technology.