Radiation-Induced Graft Polymerization of 4-Vinylpyridine on Polyethylene

Abstract

ABSTRACT:· 4-Vinyl pyridine was grafted on polyethylene films of different thicknesses by the direct irradiation method using a Co-60 y-irradiation source. Addition of different amounts of solvents such as methyl ethyl ketone and cyclohexanone was found to decrease the swelling and the grafting extent on polyethylene. The dependence of the rate of graft polymerization on the thickness of the films was studied. The rate of grafting was found to decrease with increasing film thickness and a first order dependence was obtained. The effect of radiation dose on some of the mechanical properties of the ungrafted and grafted polyethylene was examined. It was found that low doses cause an increase in elongation due to a degradation process of polyethylene chains. At high doses, elongation tends to decrease again due to crosslinking, while the tensile load is not affected. Low grafting percents of 4-vinylpyridine on polyethylene lead to a marked decrease in elongation of the grafted polymer, with almost no change in the tensile load. Increasing the extent of grafting causes a significant increase in the tensile load and almost the same decrease in elongation as for the low grafted polymer.KEY WORDS Grafting I Solvent Effect I Thickness Effect I Tensile Load ICo-60 I Y-Irradiation I Radiation-induced graft polymerization of vinylpyridine1 on preirradiated polyethylene using yradiation and accelerated electrons has been proved to proceed by radical mechanism with a considerable rate. The grafting rate was dependent on the concentration of the polymer radicals (up to 5 Mrad dose) and on the concentration of the monomer. It was reported also that diffusion plays a certain role on the grafting rate, as the latter is dependent on the thickness of the polyethylene films. Several authors2 -6 studied the radiation-induced graft polymerization of 4-vinylpyridine onto different polymeric substrates to improve their properties: such as dyeability, ion exchange capability, and capacity to prevent blood coagulation.(diffusion of monomer into the polymer) on the extent and rate of graft polymerization.Graft polymerization of 4-vinylpyridine on polyethylene, or other polymeric substrates, is not a fully studied system. Little attention has been given to studying the effect of solvents and film thickness The aim of the present work is to study the effect of the addition of different solvents, such as methyl ethyl ketone and cyclohexanone, on the swelling and the grafting extent of 4-vinylpyridine to polyethylene. The dependence of the graft polymerization rate on the film thickness was also examined by kinetic methods. We also tried to characterize mechanically the behaviour of the grafted and ungrafted polymers by investigating the effect of dose on the elongation and the tensile load of the grafted and the ungrafted polyethylene samples. The apparent and true grafting were also determined.

Synthesis and characterization of novel graft copolymers by radiation‐induced grafting

“…It was reported previously the influence of various solvents on radiation‐induced grafting of 4VP onto polyethylene,9 poly(vinyl chloride),10 styrene‐butadiene‐styrene triblock copolymer, and11 poly(tetrafluoroethylene‐ co ‐hexafluoropropylene) (FEP) 12. Compared with our work, the diversity of the results may be due to the differences of grafting method (simultaneous grafting used in literature) and base film type.…”

“…4VP has been studied previously due to its interesting property changes that can result from the presence of the polar pyridine ring. Much previous work was oriented toward radiation grafting of 4VP into various base polymers including polyethylene,9 polyvinylchloride,10 styrene‐butadiene‐styrene triblock polymer,11 poly(tetrafluoroethylene‐ co ‐hexafluoropropylene),12 and there is only limited information on the optimization of grafting and characterization 9–12. Grafting of NVP onto poly(tetrafluoroethylene),13 low density polyethylene,14 (tetrafluoroethylene‐perfluorovinyl ether) copolymer,15 poly(tetrafluoroethylene‐hexafluoropropylene‐vinylidene fluoride),16 and polypropylene17 by radiation grafting was reported earlier only in a few studies.…”

Radiation induced grafting of glycidyl methacrylate on teflon scrap for synthesis of dual type adsorbent: Process parameter standardisation

“…This clearly indicated that for practical applications of grafted Teflon scrap where functional requirement demands the availability of grafted groups the scrap of less thickness should be chosen. In reported literature there are conflicting results some reporting decrease, other increase and some no effect of backbone thickness on grafting extent [27][28][29].…”

Chemically Stable Styrenic Electrospun Membranes with Tailorable Surface Chemistry

“…Also, the conductivity of the polymer dope impacts the spinning process. For example, adding 0.5-1 wt% of sodium chloride, lithium chloride, or sodium dodecyl sulfate increased the conductivity of 8-15 wt% polystyrene/DMF solutions, 4-10 wt% polyacrylonitrile/DMF solutions, and 3-7 wt% poly(ethylene oxide)/water solutions [19,21,22] and ultimately improved the spinnability of the polymer dope solutions. Without the addition of salt, the tested polymer dope solutions were electrosprayed from the needle tip, creating particles rather than fibers.…”

“…The irradiation of polyethylene with gamma rays initiates an uncontrolled free-radical polymerization by splitting the polymer backbone, thereby generating free radicals. Then, grafted brushes are grown as monomers propagate from the main chain [22]. The irradiation of polyethylene affords little control over the polydispersity of the grafted brushes [23], with a typical polydispersity index (PDI) of around 10 [24].…”