Improving the mechanical properties and flame retardancy of ethylene‐vinyl acetate copolymer by introducing bis [3‐(triethoxysilyl) propyl] tetrasulfide modified magnesium hydroxide

Abstract

Magnesium hydroxide (MH) was surface modified by bis [3‐(triethoxysilyl) propyl] tetrasulfide (Si‐69) in order to improve its compatibility with ethylene‐vinyl acetate (EVA) copolymer substrate. The modified MH (SMH) was then introduced to EVA through melt blending. The flammability was evaluated by limiting oxygen index (LOI), vertical burning test and cone calorimeter; 40 wt% MH/SMH will lift LOI from 17.9 in EVA to 22.3/23.3, respectively. In cone test, the peak heat release rate (PHRR) of EVA is 1382 kW/m2 and reduced sharply to 601/489 kW/m2 for 40 wt% MH/SMH adding, respectively. The mechanical properties were tested by a drawing machine. The elongation at break dropped almost 7 times by the addition of 40 wt% MH, from 825% in EVA dived to 124%, whereas up to 745% by the addition of 40 wt% SMH. The morphology observation by scanning electron microscopy (SEM) indicated the dispersion of surface modified MH in EVA was remarkably improved than that of MH. Copyright © 2016 John Wiley & Sons, Ltd.