Improving interface adhesion of magnetic particle modified EVA hot melt adhesive through introduction of a thermodynamically compatible component

Abstract

In order to improve the compatibility of Fe₃O₄ particles with ethylene vinyl acetate copolymers (EVA) composite hot melt adhesives (HMAs), Fe₃O₄ magnetic particles were surface coated with polyvinyl acetate (PVAc). The PVAc-coated Fe₃O₄ modified EVA composite HMAs were characterized by SEM, DSC, XRD, optical contact angle measuring, infrared dichroism and parallel-plate rheometer measurements. The results showed that Fe₃O₄ particles were successfully coated by PVAc, leading to better dispersion of the particles in EVA composite HMAs. It was also found that the orientation structure, interfacial property and the flow properties of the modified HMAs were all changed, and the segment orientation degree and crystallinity of the modified EVA composite HMAs clearly increased with the increase of PVAc-coated Fe₃O₄ particles content. Importantly, the peel strength of the modified HMAs was further enhanced. For the modified HMAs with 15 phr (parts per hundred resins) of PVAc-coated Fe₃O₄ particles, the peel strength reached 6.6 kN m⁻¹ and was increased by 247% compared with the unmodified HMAs.