Synthesis of Poly(Methyl Methacrylate)-Caprolactam-Sericin Nanoparticles and their Reinforcing Effect on Mechanical Properties of Natural Rubber

Abstract

Two core-shell structure poly methyl methacrylate-caprolactam (PMMA-CPL) and poly methyl methacrylate-caprolactam-sericin (PMMA-CPL-SS) nanoparticles were synthesized by emulsion polymerization. A latex blending process was performed on preparation of natural rubber (NR) blends, NR/PMMA-CPL and NR/PMMA-CPL-SS. Transmission electron microscopy (TEM) images showed that PMMA-CPL and PMMA-CPL-SS nanoparticles covering on the surface of NR particles homogeneously. SEM, AFM, ATR-FTIR and DSC were used to compare the difference between NR/PMMA-CPL-SS and NR/PMMA-CPL. The results showed that addition of SS improved the smoothness and reduced the amount of incompatible particles on the surface of NR/PMMA-CPL-SS film. Due to the introduction of CPL and SS, the number of escaping particles on the surface of NR was decreased during film forming process and the Tg of NR shifted to a higher temperature. The results indicated that the interfacial adhesion and compatibility of PMMA and NR were improved. Mechanical testing showed that PMMA-CPL nanoparticles could improve the mechanical property of NR. When the content of PMMA-CPL-SS was 10%, the tensile strength of NR/PMMA-CPL-SS film was increased by 19.6% compared to NR/PMMA-CPL. Moreover, the NR/PMMA-CPL-SS film exhibited a higher hydrophilic property after modification with PMMA-CPL-SS nanoparticles.