Study on the mechanism of improving the lap-shear properties of EVA hot melt adhesives by optical preform waste powders

Abstract

A large amount of waste is produced during the preparation of optical fiber preforms, and thus the resource utilization of the optical preform waste powders is of great significance. The addition of the calcined optical preform waste powders to pure EVA hot melt adhesives can increase the lap-shear strength. To investigate the reasons for improving the mechanical properties of the pure EVA hot melt adhesives by the optical preform waste powders, XPS, ATR-IR, and Gaussian calculations were utilized to explore the mechanisms of the reactions between the optical preform waste powders and the pure EVA hot melt adhesives. It was found that the hydroxyl groups on the surface of the silicon particles reacted with the ester groups in the EVA resin through the nucleophilic addition and decomposition reactions, which resulted in the formation of long-chain alkyl alcohols and the formation of acylate on the surface of silicon particles, which reduced the agglomeration of the particles. DSC was used to characterize the crystallization behavior of the EVA composite hot melt adhesives with different contents of the optical preform waste powders. With the increase in powder content, the crystallinity of the composite hot melt adhesives decreased obviously, and the decrease in crystallinity increased the lap-shear strength of the composites. Nevertheless, when the crystallinity was too low, a high powder content tended to increase the agglomeration of the particles, which reduced the dispersion compatibility of nanoparticles and organic polymer chains, resulting in a decrease in lap-shear strength.