Fourier transform infrared spectroscopy investigations of polybenzimidazole/poly(bisphenol-A carbonate) blends

Supercritical CO2 Impregnation of Clove Extract in Polycarbonate: Effects of Operational Conditions on the Loading and Composition

The development of active packaging for food storage containers is possible through impregnation of natural extracts by supercritical CO2-assisted impregnation processes. The challenge of scCO2-impregnation of natural extracts is to control the total loading and to ensure that the composition of the loaded extract may preserve the properties of the crude extract. This study aimed at investigating the scCO2-impregnation of clove extract (CE) in polycarbonate (PC) to develop antibacterial packaging. A design of experiments was applied to evaluate the influences of temperature (35–60 °C) and pressure (10–30 MPa) on the clove loading (CL%) and on the composition of the loaded extract. The CL% ranged from 6.8 to 18.5%, and the highest CL% was reached at 60 °C and 10 MPa. The composition of the impregnated extract was dependent on the impregnation conditions, and it differed from the crude extract, being richer in eugenol (81.31–86.28% compared to 70.06 in the crude extract). Differential scanning calorimetry showed a high plasticizing effect of CE on PC, and high CL% led to the cracking of the PC surface. Due to the high loading of eugenol, which is responsible for the antibacterial properties of the CE, the impregnated PC is promising for producing antibacterial food containers.

Infrared Spectroscopy of Polybenzimidazole in the Dry and Hydrate Forms: A Combined Experimental and Computational Study

In the present article, the infrared spectrum of polybenzimidazole (PBI) in the dry and hydrate forms has been studied both experimentally and theoretically to improve the interpretation of its complex features, especially in the ν(NH)/ν(OH) range, which is extensively affected by sorbed water and temperature. Time-resolved Fourier-transform infrared spectroscopy measurements were performed to monitor H2O sorption, whereas the temperature behavior was investigated by in situ measurements in the 100-450 °C range. Density functional theory calculations on simplified models of dry and hydrated PBI showed good agreement with experimental results and allowed a reliable interpretation of the observed effects. The combined experimental/computational analysis provided relevant structural information which suggested the possibility of modifying the diffusion properties of PBI and motivated further experimental activities.

Studies of poly(styrene-co-allyl alcohol)/polyester blends using Fourier transform infrared spectroscopy and imaging

The interaction of poly(styrene-co-allyl alcohol) and aliphatic polyester was studied using FT-IR spectroscopy. The hydrogen bonding between two polymers was investigated by monitoring C=O and OH stretching modes with the variation of concentration and temperature. The phase-separated morphology was also observed using FT-IR imaging, where the spectroscopic analysis of each phase is available.