Strong Interfacial Adhesion and Good Heat Stability of PET/Rubber Composites Modified by Developing New Eco-Friendly Dipping System

PET fibers are commonly utilized in fiber-reinforced rubber composites due to their excellent properties as a structure backbone. However, the interfacial bonding between PET fibers and rubber is often inadequate, primarily due to the chemical inertness of PET fibers. Traditionally, the RFL impregnation system has been employed for the surface modification of PET fibers. In this study, we introduce a novel environmentally friendly impregnation system named G-SML designed to address these concerns while minimizing environmental impact and ensuring researcher safety. The system activates polyester fibers (PET) by using glycerol triglycidyl ether. Subsequently, the activated fibers were impregnated with a solution comprising sorbitol glycidyl ether (SGE), 2-ethyl-4-methylimidazole (MZ), and styrene–butadiene–vinylpyridine (VP) latex. The primary focus of this investigation was on examining the influence of the SGE/MZ ratio on adhesion between PET and styrene butadiene rubber. Characterization techniques such as attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy were employed to analyze the surface chemical structure of PET fibers before and after modification. Additionally, we elucidated the mechanism underlying the adhesion between modified fibers and the rubber. Results from H pull-out tests and 180° peeling tests indicated that at an SGE/MZ ratio of 5/4, withdrawal forces reached up to 78 N, while peeling forces achieved 15.3 N/root. Furthermore, optimal adhesive properties, along with enhanced aging stability, were observed at this ratio. This research provides valuable insights into the design and development of environmentally friendly impregnating solutions.