Y. Zhang, B. B. Wang, H. B. Sheng, B. H. Yuan, B. Yu, G. Tang, G. X. Jie, H. Feng, Y. J. Tao and Y. Hu (2016) Enhanced fire-retardancy of poly(ethylene vinyl acetate) electrical cable coatings containing microencapsulated ammonium polyphosphate as intumescent flame retardant. Journal/Rsc Advances 6 85564-85573. [In English]
Web link: http://dx.doi.org/10.1039/c6ra15314c
Keywords: VINYL ACETATE COPOLYMER, CHAR-FORMING AGENT, MECHANICAL-PROPERTIES, THERMAL-DEGRADATION, EVA COPOLYMER, EPOXY-RESIN, IN-SITU, COMPOSITES, NANOCOMPOSITES, POLYPROPYLENE

Abstract: There is a need to improve and maintain the protection function of ethylene-vinyl acetate copolymer (EVA) cable materials from ageing degradation to avoid fire hazards and extend their service lives. Here, a flame retardant, branched silane precursor, pentaerythritol triacrylate-(3-aminopropyl) triethoxysilane (PETA-APTS), containing a vinyl group and hydrolysable silane structure was successfully synthesized and characterized, and it was used to prepare microencapsulated ammonium polyphosphate (MCAPP) particles with tetraethoxy silane via a successive Stober method, which aimed to immobilize the MCAPP into the EVA matrix through a crosslinking treatment. Damp-heat ageing tests (85 degrees C, 85% R.H.) were carried out on the EVA/APP (EVA-1 system) and EVA/MCAPP (EVA-2 system) to explore the protective effect of the microencapsulation method over 6 weeks. Digital photos, SEM images, gel-content tests and X-ray photoelectron spectroscopy results showed that the MCAPP particles had excellent compatibility with the EVA matrix and did not migrate or eroded with water vapor at 85 degrees C. Remarkably, this phenomenon led to great improvements in the mechanical properties, electrical insulation performance and fire safety for the EVA-2 system compared to the EVA-1 system. This investigation provided a formulation for the industrial application of the EVA/IFR cable as an insulated material with excellent long-term stability and fire safety.