A. M. Rabie

pH-sensitive sodium alginate hydrogels for riboflavin controlled release

Sodium alginate (SA) grafted with polyglycidyl methacrylate hydrogels (PGMA-g-SA) was prepared as pH sensitive drug delivery matrices for riboflavin (RF). The hydrogel copolymer matrices were compared with calcium alginate (CA) beads for swelling, degradation, entrapment efficiency and in vitro release of RF. The structure, surface morphology of the CA beads and the prepared hydrogels as well as the chemical stability of the encapsulated drug were characterized by FT-IR and SEM, respectively. The results demonstrate that the optimal formulation was achieved with PGMA-g-SA proportion of (0.75 mol/1 g) and loaded RF 0.03 g. It has been observed that the in vitro release study of RF from this formulation was superior to the other ones and was able to maintain the release for ∼3 and 4 days for the simulated intestinal fluid (SIF) and simulated gastric fluid (SGF), respectively. In general, it has been shown that, GMA grafted onto SA enhanced drug entrapment efficiency, decreased swelling and degradation behaviors of the carrier. In addition, it slowed and controlled the release of RF from the PGMA-g-SA hydrogel compared with pure SA beads crosslinked with Ca2+ ions alone, which thereby provides a facile and effective method to improve the drug delivery systems.

Comparison of the degradability of irradiated polypropylene and poly(propylene-co-ethylene) in the natural environment

Evaluation of the degradability of irradiated polymers under natural environmental conditions may give useful information about the possible rapid degradation of waste polymer materials for environmental conservation. The degradability in various environments of poly(propylene-co-ethylene), CPP, after irradiation has been investigated. The degradability of the CPP in the natural environment, evaluated by strength and elongation tests, during storage after irradiation was slower than that of polypropylene (PP). Thus, CPP required a larger dose to achieve the same degradability as PP. However, molecular scission of the CPP during roof storage was almost the same as that of PP. The CPP has a lower crystallinity and a smaller spherulite size than PP. Thus, the degradability measured by the tension test of irradiated CPP during storage was different from that of PP. However, it was confirmed that irradiation was effective in accelerating degradation of CPP during outdoor storage.

Accelerated degradability of polypropylene by blended rubber

Abstract To accelerate degradability during electron beam (EB) irradiation and during Xe exposure after EB irradiation of polymer materials, various rubbers were added to polypropylene (PP). Among the rubbers tested, butyl rubber (BR) and polyisoprene (PIS) kneaded with PP had higher compatibility as evaluated by the haze value. A small amount of rubber (1–3 wt%) induced a significant reduction of elongation and molecular weight during EB irradiation and during Xe exposure after EB irradiation of PP. The rubber was highly oxidized, leading to greater degradation of the PP. Accordingly, it was concluded that the addition of a small amount of rubber is effective in enhancing of the radiation degradability of PP. This technology might be useful for the modification of polymer materials to promote their easy decomposition in the natural environment.