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

Abstract

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 (CO 2 ) 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.

Retardation effect of nanohydroxyapatite on the hydrolytic degradation of poly (lactic acid)

“…The decrease in molar mass and polydispersity indicates that a bulk degradation occurred, hence not restricted to the surface. [17] No significant differences were observed in molar mass and polydispersity of the samples, either regarding the presence of nHA, or relative to the hydrolysis test temperature. Figure 4 shows the logarithmic curves of the weight loss (20%) as a function of 1/T and Table 3 presents the E a for a 20% weight loss for PLA and PLA/nHA composites.…”

“…[2,10,16] Therefore, the hydrolytic degradation of PLA composites can be estimated from weight loss measurements. [17][18][19] The incorporation of fillers increases the complexity of the hydrolytic degradation of PLA, depending on nature and dispersion of the filler, matrix crystallinity, and degradation temperature. [9] Few studies on the hydrolytic degradation of PLA containing nanoparticles have been performed, being clays the most investigated nanoparticles.…”

Development of three-dimensional printing filaments based on poly(lactic acid)/hydroxyapatite composites with potential for tissue engineering

“…9 Different methods are available for fabricating bone scaffolds, using polymers, ceramics, and the combination of these materials by solvent casting, particle leaching, freeze drying, thermally induced phase separation, and gas foaming. 10 However, these techniques have limitations, such as difficult control of the internal micro-architecture (shape, size and distribution of pores) and presence of cytotoxic solvents. 11 Additive manufacturing (AM) allows the obtaining of scaffolds with customized external shape, and predefined internal porosity and interconnectivity.…”

Contributions of supercritical fluid technology for advancing decellularization and postprocessing of viable biological materials

“…177 This technology has been used since the 1990s 178 for polymer processing. The foaming processes reported in the literature are mainly focused on polymer scaffolds, like polycaprolactone (PCL) 179 and poly-lactic acid (PLA) matrices, 180–183 polystyrene, 184–187 and polyurethane 188,189 foams. From the preparation of inert polymeric support to functional scaffolds, supercritical fluid foaming has been explored for the preparation of polymeric systems incorporated with bioactive agents.…”