No abstract

No abstract

For the preparation of fully biobased unsaturated polyester resins (UPRs), the replacement of styrene with alternate nonpetroleum-based monomers turned out to be one of the most challenging tasks. Its complexity lies in the fact that reactive diluents (RD) have to have low viscosity and volatility, good compatibility with prepolymer, and capability to homopolymerize and copolymerize with its unsaturations. In this context, we directed our efforts to develop fully biobased UPRs using the dialkyl itaconates as an alternative to styrene. Therefore, a series of 100% biobased UPRs were prepared from itaconic acid and 1,2-propandiol and diluted by dialkyl itaconates. The resins were characterized by Fourier transform infrared spectroscopy, NMR, volatility, and viscosity measurements, while the cured samples were characterized by dynamic mechanical properties, thermomechanical analysis, thermogravimetric analysis data, and tensile tests. The influence of RD structure on the properties of cured samples was discussed in detail. It was shown that the prepared resins had evaporation rates of dialkyl itaconates of several orders of magnitude less compared to styrene. The cured resins with dimethyl itaconate showed comparable or even better thermal and mechanical properties compared to the one with styrene. This investigation showed that itaconic acid and dialkyl itaconates are promising bioresources for the preparation of fully biobased UPRs for mass consumption.

The glycolytic recycling of waste PET presents a challenge for the production of secondary value-added products, such as alkyd resins. A way to overcome unsatisfactory mechanical, drying and chemical resistance properties met with alkyds obtained from difunctional glycolyzates, was proposed. Waste PET was glycolyzed using multifunctional alcohols: glycerol (G), trimethylolethane (TME), trimethylolpropane (TMP) and pentaerythritol (PE), giving tetra-and hexa-functional glycolyzates and, for comparison, using diethylene glycol (DEG), propylene glycol (PG) and dipropylene glycol (DPG) giving di-functional glycolyzates. The obtained glycolyzates were examined by 1 H and 13 C NMR, FTIR spectroscopy and elemental analysis and further used in the synthesis of alkyd resins. The properties of the prepared alkyd resins (acid, hydroxyl and iodine values, color, average molar masses and molar mass distributions, viscosity, drying time, hardness, flexibility, gloss, adhesion and chemical resistance) were investigated with respect to the functionality and the structure of the used glycolyzates. Alkyd resins derived from multifunctional glycolyzates (TME and TMP) showed considerably enhanced properties compared to those produced from difunctional glycolyzates and also to conventional general purpose resins.Please do not adjust margins Please do not adjust margins decreased the branching degree. Future work on this matter will involve the preparation, analysis and application of lacquers, paints and anticorrosive coatings based on the presented alkyd resins.

Novel pH-sensitive hydrogels based on chitosan, itaconic acid and methacrylic acid were prepared in two steps. Chitosan was first ionically crosslinked with itaconic acid, after which a free radical polymerization and crosslinking of the chitosan/itaconic acid network was performed by adding methacrylic acid and a crosslinker in order to achieve better mechanical properties and tunable swelling. The samples were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, dynamic mechanical analysis and the swelling ratios of the hydrogels at various pH values (2.0-8.0). The hydrogel composition is found to have a great impact on the hydrogel structure, mechanical and thermal properties, morphology and swelling kinetics. The highly porous morphology of the gels is probably connected with the bulky chitosan/itaconic acid network which reduces the degree of crosslinking in the second step of the synthesis due to steric hindrances. The gels demonstrate substantial change in buffer absorbency with change of pH, low for acid buffers and the higher for pH values above 6 where the swelling is considerably slow, thus suggesting their strong candidature for use as oral drug-delivery systems in the lower parts of the gastrointestinal tract and for drugs that require longer release times. Effect of pH on swellingThe effect of pH on the equilibrium water uptake of the samples was determined in buffers of varying pH, ranging from 2.0 to 8.0, at 25 • C. Figure 3 shows the change of q e with pH. Chitosan is a Polym Int 2011; 60: 443-452

Chitosan is a biodegradable, non‐toxic, biocompatible polymer convenient for use in drug delivery. In this study, hybrid polymeric networks (HPNs) based on chitosan, itaconic acid and poly(vinyl alcohol) (PVA) were prepared and characterized. Chitosan was dissolved in itaconic acid in order to obtain ionic crosslinking with the dicarboxylic acid. In the second step, this chitosan/itaconic acid network was mixed with PVA and chemically crosslinked with glutaraldehyde. The chitosan/itaconic acid ratio was kept constant, while the concentrations of PVA and glutaraldehyde were varied. All samples were characterized using swelling studies, dynamic mechanical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction and scanning electron microscopy. The equilibrium degrees of swelling obtained for the HPNs were higher than most of the values reported for chitosan hydrogels obtained by dissolving chitosan in acetic acid or HCl aqueous solutions. This method of synthesis also resulted in hydrogels with better mechanical properties and thermal stability. By changing the PVA content and the degree of crosslinking, it is possible to finely tune the properties of the HPNs, which could make them suitable as potential matrices in controlled drug delivery. Copyright © 2010 Society of Chemical Industry

No abstract

No abstract