Construction of an in situ interfacial layer for aramid fiber reinforced styrene butadiene rubber composites

In this work, the in situ interface layer composite was prepared by using the coating agent dispersion. Aramid fiber (AF) was modified with lithium chloride aqueous solution, and then coated with the blends of a low-molecular weight maleated polybutadiene liquid rubber (MLPB), the epoxy resin (E51), and 2-ethyl-4-methylimidazole (2E4MZ). The in situ interface layer was formed via the reaction of epoxy group with anhydride group in the presence of the accelerator 2E4MZ and covulcanization of MLPB with styrene butadiene rubber (SBR) in the process of preparing vulcanized AF reinforced SBR. It can be seen from analysis of scanning electronic microscopy, attenuated total reflection Fourier transform infrared, and thermogravimetric analysis that the in situ interfacial layer was a uniform and dense interfacial layer on the fiber surface and was not be destroyed during processing. The results of the dynamic mechanical analysis and mechanical properties showed that the in situ interface layer formed in processing had higher flexibility and better integrity than the interface layer prepared before processing, which is favorable for stress relaxation, and the in situ interface layer imparts better tensile strength and tear strength to the composite. The 100% modulus of composites with in situ interface layers was 14.6% higher than that of composites prepared without uncoated AF.