Anne George

Dynamic mechanical properties of thermoplastic elastomers from blends of polypropylene with copolymers of ethylene with vinyl acetate

Abstract Thermoplastic elastomers from blends of ethylene-vinyl acetate copolymer and polypropylene have been prepared by melt blending in a Brabender Plasticorder. Dynamic mechanical properties such as storage modulus, loss modulus and damping properties were studied over a wide range of temperatures. The effects of blend ratio and dynamic crosslinking of the elastomer phase on the dynamic mechanical properties have also been investigated. The morphology of the blends has been studied by scanning electron microscopy. Both microscopy and dynamic mechanical analysis indicate that the blends are immiscible and they have a two-phase structure. Attempts have been made to correlate the dynamic mechanical properties with the morphology of the system. Various composite models have been used to fit the experimental viscoelastic data.

Grafting of butyl acrylate onto gelatin in a water-isopropanol medium

Abstract Graft copolymerization of butyl acrylate onto gelatin using potassium persulphate initiator was studied in a water-isopropanol medium. The crude graft copolymers were soxhlet extracted with acetone to remove the loosely bound ungrafted homopolymer. The influence of a number of experimental factors such as effect of time, monomer concentration, initiator concentration, backbone concentration and temperature on the graft copolymerization of gelatin were investigated.

Grafting of Acrylonitrile onto Gelatin in Zinc Chloride Medium

Abstract Grafting of gelatin with acrylonitrile in zinc chloride medium has been studied using potassium persulfate as the initiator. The rate of grafting, grafting efficiency, and percentage of grafting are calculated. The grafting results are discussed in the light of the rate of grafting. The enhanced activity of the monomer is due to the formation of AN … ZnCl2 complexes.

Graft copolymerization of ethyl acrylate on gelatin in water-acetic acid medium

Abstract Gelatin was graft copolymerized with ethyl acrylate in water-acetic acid medium (1:1. v/v). Effects of experimental variables such as reaction time and concentrations of monomer, initiator and gelatin were studied. The results are discussed in terms of rate of grafting and percentage of grafting. These quantities were found to be lower than for gelatin-g-poly(ethyl acrylate) copolymers in aqueous and water-isopropanol media.

Dendrimers: General Aspects, Applications and Structural Exploitations as Prodrug/Drug-delivery Vehicles in Current Medicine

Dendrimers are hyper branched macro molecules with well-defined structure and high degree of functionality on the surface. The dendrimer architecture allows control over properties such as shape, size, density, polarity, reactivity, solubility etc. These special features can be exploited to design molecules having desired properties used for biomedical applications. Recent advancements in correlation between structure and biodegradability and in vivo performance are opening up new avenues for these molecules; particularly, in biological applications like drug delivery. The unique structure of dendrimers provides enough attachment sites for drugs. Further, it is possible to tune the molecules in such a way so that the drug molecules are encapsulated outside the target area and are released only in the local environment of targets. This review presents some general aspects of dendrimers and how their properties are exploited for drug delivery applications.