Halogen‐free flame‐retardant cable compounds: Influence of magnesium‐di‐hydroxide filler and coupling agent on EVA/LLDPE blend system morphology

Objective of this work was to deeper understand the influence of a grafted coupling agent in EVA/LLDPE based blends containing mineral filler acting as a flame‐retardant. EVA/LLDPE blends (50:50 phr) containing magnesium‐di‐hydroxide (MDH) were compounded. For comparison, parts (4%–5%) of LLDPE were substituted with MAA‐g‐LLDPE copolymer as a coupling agent. No influence of the coupling agent was observed by differential scanning calorimetry (DSC) thermal analysis. A strong influence of different filler ratios (0%–60%) was detected by rheological investigations. Morphological studies revealed significant differences in blend morphology and filler location caused by phase transition which is close to the 50:50 composition. The coupling agent improved the compatibility of the blend in that a reduced phase size could be observed. The addition of the coupling agent relocated the mineral filler from being mainly located in the EVA phase into the interphase and created a connection between both polymeric phases which resulted in improved thermo‐mechanical performance.