Effect of SEBS on water treeing behaviors of cross-linked polyethylene
We investigated the effect of an aromatic polymer, styrene-(co-ethylene-butadiene)-styrene (SEBS), on water tree resistance of cross-linked polyethylene (XLPE). The XLPE/SEBS samples were characterized by means of gel content determination, different scanning calorimetry (DSC), scanning electron microscopy (SEM) and the accelerated water treeing experiment. Our results clearly indicated that the samples with SEBS showed improved water tree resistance in comparison to blank samples. It was also found that the blends had excellent dielectric property form the viewpoint of practical application.
Compatibilizing Effect of SEBS for Electrical Properties of LDPE/PS Blends
In the previous study, we observed compatibilizing effects of low density polyethylene (LDPE)/polystyrene (PS) with polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS), a triblock copolymer. Blends consisting of 70 wt.-% LDPE and 30 wt.-% PS were prepared with a SEBS concentration of up to 10 wt.-%. This study examined the electrical properties such as the electrical breakdown, water tree length, permittivity and tan δ in the blends. The possibility of using these blends as insulating material substitutes for LDPE was investigated. The electrica break-LDPE. The permittivity of the blends was 2.28-2.48 F/m, exception of S-0. Tan δ of the blends increased smoothly with increasing SEBS content.
Dynamic mechanical properties of methacrylic-acid-grafted polyethylene films
A dynamical mechanical relaxation study has been made of low density polyethylene films to which methacrylic acid has been grafted by ..gamma.. irradiation. The grafted films retain the original degree of crystallinity and show only slight changes in melting points and melt viscosities, indicating that the grafted methacrylic acid side chains are long, few in number, and completely phase separated from the polyethylene matrix. Three dispersion regions are observed in plots of the loss modulus, E'' vs. temperature at constant frequency and these are labeled ..gamma.., ..beta.., ..cap alpha..', in order of increasing temperature. The ..cap alpha..' peak, above 215/sup 0/C, was assigned to microbrownian segmental motions accompanying the T/sub g/ of polymethacrylic acid. The ..beta.. peak, at -20/sup 0/C, was assigned to motions accompanying the T/sub g/ of branched polyethylene, and the ..gamma.. peak, at -120/sup 0/C, was assigned to local motions of a few CH/sub 2/ sequences in polyethylene.