the degradation of poly (vinyl pyrrolidone) (pvp) by means of ultrasound irradiation and itscombination with heterogenous photocatalysis (tio2 nanoparticles) was investigated. emphasiswas given on the effect of additive on degradation rate constants. 24 khz of ultrasoundirradiation was provided by a sonicator, while an ultraviolet source of 30 w was used for uvirradiation. to increase the effic...

in the present work, a titanium-based ziegler-natta catalyst was employed to synthesize ultra molecular weight polyethylene in a slurry medium. the effect of different parameters such as ethylene pressure, temperature, catalyst composition, and hydrogen pressure was studied. as the results indicate, increasing either [al]/[ti] ratio or temperature causes polymerization rate to go through a maxi...

Polymers are large molecules consisting of a large number of small component molecules chemically linked together. They are made from constituent monomers through polymerization process. Polymers are unique materials in that they consist of a statistical distribution of chains of varying lengths, and each chain consists of monomer residues which affect its properties hence they require several ...

2014 Intrinsic viscosity measurements have been performed on polystyrene-cyclohexane system as a function of temperature T (T ~ 03B8 and as a function of molecular weight (8.2 x 104 ~ Mw ~ 2.06 x 107) .The expansion factor 03B13~ = [~]/[~03B8] of the intrinsic viscosity [~] scales with the reduced variable (T 2014 03B8/T) · ~Mw. For (T201403B8/T) ” ~Mw ~ 2014 40, the intrinsic viscosity of a co...