Cross-linking, morphology and properties in polymer blends and composites

Three electrically conductive carbon containing composites were studied: (1) ethylene vinyl acetate (EVA)/carbon fibers (CF), (2) ethylene-butene copolymer (EBC)/electrically conductive carbon black (CB) and (3) EBC/CF. The composites were prepared by mixing on a two-roll mill or in a Brabender. Sheets were prepared by compression molding. The influence of electron beam irradiation at levels 60, 120 and 180 kGy was studied for EVA/CF composites. Gel content study helped in calculation of the parameters in Charlesby-Pinner equation. Parameters G(X) = 3.78 and G(S) = 2.35 mean that both cross-linking and chain scission occur during e-beam irradiation. The ratio of the parameters G(X)/G(S) = 1.61 indicates that cross-linking prevails over the scission for this EVA copolymer. Room temperature (25°C) and high-temperature (150°C) mechanical properties (creep, stress-strain and frequency sweep) were studied by dynamic mechanical analysis (DMA). The influence of electron beam irradiation was best observed at 150°C; there was a systematic decrease in creep, increase in stress at given strain, increase in real part of shear modulus G’ and decrease in loss factor (tan delta). The experimentally obtained increase in modulus due to the addition of carbon fibers was discussed with the help of Guth-Gold and Guth-Smallwood models. Shape factor L/D was estimated by direct observation by optical microscopy. The composites were tested for changes in electrical resistance during the stretching by various forces. Gauge factor, defined as the ratio of relative change in electrical resistance to the mechanical strain, was calculated. Several composites showed significant changes in electrical resistance during stretching showing a potential use of these electrically conductive composites as strain sensors that could be used for example as artificial muscles in robotics.

ISBN:	978-80-7454-998-4
EAN:	9788074549984
Počet stran	56 stran
Datum vydání	09. 06. 2021
Pořadí vydání	První
Jazyk	anglický
Vazba	e-kniha - pdf
Autor:	Yasin Hamid
Nakladatelství	Univerzita Tomáše Bati ve Zlíně
Tématická skupina	999 - nezařazeno
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