Supercritical Foaming and Impregnation of Polycaprolactone and Polycaprolactone-Hydroxyapatite Composites with Carvacrol

Abstract

Polycaprolactone (PCL) and polycaprolactone-hydroxyapatite (PCL-HA) scaffolds were produced by foaming in supercritical carbon dioxide (scCO2) at 20 MPa, as well as in one-step foaming and impregnation process using carvacrol as an antibacterial agent with proven activity against Gram-positive and Gram-negative bacteria. The experimental design was developed to study the influence of temperature (40 °C and 50 °C), HA content (10 and 20 wt.%), and depressurization rate (one and two-step decompression) on the foams’ morphology, porosity, pore size distribution, and carvacrol impregnation yield. The characterization of the foams was carried out using scanning electron microscopy (SEM, SEM-FIB), Gay-Lussac density bottle measurements, and Fourier–transform infrared (FTIR) analyses. The obtained results demonstrate that processing PCL and PCL-HA scaffolds by means of scCO2 foaming enables preparing foams with porosity in the range of 65.55–74.39% and 61.98–67.13%, at 40 °C and 50 °C, respectively. The presence of carvacrol led to a lower porosity. At 40 °C and one-step decompression at a slow rate, the porosity of impregnated scaffolds was higher than at 50 °C and two- step fast decompression. However, a narrower pore size distribution was obtained at the last processing conditions. PCL scaffolds with HA resulted in higher carvacrol impregnation yields than neat PCL foams. The highest carvacrol loading (10.57%) was observed in the scaffold with 10 wt.% HA obtained at 50 °C.

Comprehensive Volumetric Property of Eco-Friendly Pressurized Fluids by Experimental, Theoretical Modeling, and MD Simulation for Sustainable Oil Extraction from Waste Rice Bran

“…Determining the density of pressurized fluids involves various experimental methods . Some of these methods include hydrostatic weighing, − floating meter, density bottle, vibrating densimeter, − laser okhim fiber optic densitometer, singlesinker densimeter, γ densitometer, and an in-house designed PVT apparatus. − The hydrostatic weighing method incorporates an enhanced static weighing technique employing a magnetic suspension balance, based on Archimedes’ principle. However, this method requires different calibration floats for different samples, which can impact sample buoyancy and density accuracy .…”

Effect of the Processing Conditions on the Supercritical Extraction and Impregnation of Rosemary Essential Oil in Linear Low-Density Polyethylene Films

“…The impregnation process has been studied for the incorporation of clove essential oil in linear low-density polyethylene (LLDPE) films [27], cinnamaldehyde in poly(lactic acid) (PLA) films [28], thymol in poly(lactic acid) /Polycaprolactone (PLA/PCL) films [29], lycopene in hydrolyzed collagen [30], lavandin essential oil in octenyl succinic anhydride (OSA) modified starch produced from waxy maize [31], chia oil in soy protein [32], Pulicaria jaubertii in gum arabic [33], eugenol in LLDPE films [34], carvone in PLA films [35], a mixture of two terpene ketones in low density polyethylene (LDPE) films [36], cinnamaldehyde into cassava starch films [37], terpene ketones with insecticidal properties in LDPE/sepiolite nanocomposite films [38], antioxidant mango polyphenols into polyethylene terephthalate (PET)/Polypropylene (PP) films [39], olive leaf extract polyphenols charged into PET/PP films [40], eugenol into polyamide fibers [41], LDPE films loaded with carvone [42], PLA films with thymol [43], ibuprofen into poly(methyl methacrylate) (PMMA) films [44], mefenamic acid in PMMA [45], carvacrol in composite PCL [46], and Zataria multiflora Impregnation in PLA films [47]. In all the conducted studies pressure, temperature, time, and depressurization rate were considered as the parameters affecting the SSI process efficiency.…”