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Morphology, Resistivity, and PTC behavior of EVOH/CB composites prepared by solvent‐casting saponification and precipitation saponification
Author(s) -
Lee EunJu,
Park EunSoo
Publication year - 2017
Publication title -
polymer composites
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.577
H-Index - 82
eISSN - 1548-0569
pISSN - 0272-8397
DOI - 10.1002/pc.23714
Subject(s) - saponification , materials science , composite material , high density polyethylene , casting , ethylene vinyl acetate , composite number , morphology (biology) , polyethylene , polymer chemistry , polymer , copolymer , organic chemistry , chemistry , biology , genetics
Poly(ethylene‐ co ‐vinyl alcohol)/carbon black (EVOH/CB) composites were prepared by a solvent‐casting saponification (‐D) and precipitation saponification (‐P) methods with a poly(ethylene‐ co ‐vinyl acetate)/CB (EVA/CB) toluene suspension. The effects of the CB content and saponification time on the morphology, electrical resistivity, thermal, and mechanical properties of EVA/CB composites were examined. The volume resistivity ( ρ v ) of the EVA/CB‐D and EVA/CB‐P samples decreased significantly with increasing CB content and the percolation threshold of such composites was determined about 10 wt%. At 10 wt% of CB content, the ρ v of EVA/CB‐D composite decreased significantly with the saponification time, whereas ρ v of EVA/CB‐P composites did not change. As the saponification time increased, EVA/CB25wt% composites form cavity structure which CB is usually located in oval cavities larger than the particles themselves. This oval cavity structure almost resembles extruded high‐density polyethylene (HDPE)/CB composites. The morphology and PTC behavior of prepared composites were compared with those of HDPE/CB and the mechanism of PTC and NTC effects was discussed. POLYM. COMPOS., 38:1462–1473, 2017. © 2015 Society of Plastics Engineers