Bio-Based Polyols from Seed Oils for Water-Blown Rigid Polyurethane Foam Preparation

The preparation of water-blown rigid polyurethane (RPUR) foams using bio-based polyols from sesame seed oil and pumpkin seed oil has been reported. Polyols synthesis involved two steps, namely, hydroxylation and alcoholysis reaction. FTIR, NMR, and ESI-MS were used to monitor the process of the synthesized polyols and their physicochemical properties were determined. The resulting polyols have OH number in the range of 340–351 mg KOH/g. RPUR foams blown with water were produced from the reaction of biopolyols with commercial polymeric methylene diphenyl diisocyanate (PMDI). The proper PUR formulations can be manipulated to produce the desired material applications. These seed oil-based RPUR foams exhibited relatively high compressive strength (237.7–240.2 kPa) with the density in the range of 40–45 kg/m3. Additionally, the cell foam morphology investigated by scanning electron microscope indicated that their cellular structure presented mostly polygonal closed cells. The experimental results demonstrate that these bio-based polyols can be used as an alternative starting material for RPUR production

Addition of 4- Phenyltriazolinedione toCarbonyl Compounds: The Formation of alpha-Urazolylcarbonyl Compounds

N-Phenyltriazolinedione (PTAD) adds to a variety of carbonyl compounds to form -urazolylcarbonyl compounds. With highly enolized carbonyl systems, this type of substitution reaction can occur rapidly even in the absence of a catalyst. However, with simple carbonyl systems, the reaction is greatly accelerated by an acid catalyst such as trifluoroacetic acid. Unsymmetrical ketones afford isomeric ��- and ��\u27-urazolyl ketones, and the initially formed monourazoles can be further urazolated to the diurazoles through the application of more than 1 equiv of PTAD

Preparation and evaluation of chitosan/carrageenan beads for controlled release of sodium diclofenac

The polyelectrolyte complex (PEC) hydrogel beads based on chitosan (CS) and carrageenan (CR) have been studied as a controlled release device to deliver sodium diclofenac (DFNa) in the simulated gastrointestinal condition. Various factors potentially influencing the drug release (ie, CS/CR proportion, DFNa content, types and amount of cross-linking agents) were also investigated. The optimal formulation was obtained with CS/CR proportion of 2/1 and 5% (wt/vol) DFNa. The controlled release of the drug from this formulation was superior to other formulations and was able to maintain the release for ∼8 hours. Upon cross-linking with glutaric acid and glutaraldehyde, the resulting beads were found to be more efficient for prolonged drug release than their non-cross-linking counterparts. The bead cross-linked with glutaraldehyde was able to control the release of the drug over 24 hours. The difference in the drug release behavior can be attributed to the differences in ionic interaction between the oppositely charged ions and to the concentrations of the drug within the beads, which depends on the compositions of the formulation and the pH of the dissolution medium. The release of drug was controlled by the mechanism of the dissolution of DFNa in the dissolution medium and the diffusion of DFNa through the hydrogel beads