Polymer Institute

Formulations of chemically cross-linked poly(ethylene vinyl acetate) (EVA) and low density polyethylene (LDPE) blends containing metal hydroxides flame retardants such as aluminum hydroxide (ATH) and magnesium hydroxide (MH) were prepared. Comparison of both type of metal hydroxides in respect of their influence on flammability as well as mechanical, thermal, and electrical properties of EVA/LDPE composites is presented. Most of the

Photochemically mediated reversible-deactivation radical polymerization of methyl methacrylate was successfully performed using 50–400 ppm of various copper compounds such as CuSO4·5H2O, copper acetate, copper triflate and copper acetylacetonate as catalysts. The copper catalysts were reduced in situ by irradiation at wavelengths of 366–546 nm, without using any additional reducing agent. Bromopropionitrile was used as an initiator. The effects of various solvents and the concentration and structure of ligands were investigated. Well-defined polymers were obtained when at least 100 or 200 ppm of any catalyst complexed with excess tris(2-pyridylmethyl)amine as a ligand was used in dimethyl sulfoxide as a solvent.

Well-defined poly(methyl methacrylate) was prepared by a photochemically induced reversible deactivation radical polymerization using 50−200 ppm of copper catalyst in dimethyl sulfoxide under both an inert atmosphere and in the presence of limited amount of air. Effect of the ligand structure and concentration on kinetics and polymerization control was investigated. Under inert atmosphere, equimolar amount of the ligand, such as tris(2-pyridylmethyl)amine (TPMA) or N,N,N’,N’’,N’’-pentamethyldiethylenetriamine (PMDETA), was sufficient to achieve well-controlled polymerization of MMA. In the presence of air, a well-controlled polymerization started just after some induction time, which was dependent on the concentration of TPMA ligand. Irradiation at λ > 350 nm provided both a photochemical reduction of an initially-added copper(II) catalyst, which complexed with either PMDETA or TPMA ligand, to a copper(I) activator, and photochemical regeneration of the copper(I) activator after ...