Preparation of fast-degrading poly(lactic acid)/soy protein concentrate biocomposite foams via supercritical CO2 foaming

Tong Liu, Xiang Fang Peng, Hao Yang Mi, Heng Li, Lih Sheng Turng, Bai Ping Xu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

6 Citations (Scopus)


To increase the degradation rate of poly(lactic acid) (PLA), soy protein concentrate (SPC) was introduced via melt compounding using a self-developed, co-rotating, non-twin-screw extruder. Poly(2-ethyl-2-oxazoline) (PEOX) and diphenyl methane diisocyanate (MDI) were added to plasticize the melt and improve the compatibility between PLA and SPC. The PLA/SPC blends were subsequently foamed using supercritical carbon dioxide (CO2) as a blowing agent to produce porous composites. The involvement of SPC promoted cold crystallization of PLA but reduced the thermal stability of the blends. PLA showed a strong interfacial bonding with modified SPC, and the SPC formed continuous three-dimensional networks when its proportion reached 30 wt%. In the foaming process, SPC domains acted as heterogeneous nucleation sites, which resulted in enhanced cell densities and reduced cell diameters. The PLA/SPC (70:30) sample showed the finest cell structure due to the presence of the SPC network. For the same blends, increasing the foaming pressure from 16 to 20 MPa enhanced the cell density by about 5 times. The water absorption rate and the biodegradation rate of the PLA/SPC foams were much higher than that of neat PLA due to the hydrophilicity of SPC and the porous structure of the foams. POLYM. ENG. SCI., 59:1753–1762, 2019.

Original languageEnglish
Pages (from-to)1753-1762
Number of pages10
JournalPolymer Engineering and Science
Issue number9
Publication statusPublished - 1 Sep 2019

ASJC Scopus subject areas

  • Chemistry(all)
  • Polymers and Plastics
  • Materials Chemistry

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