Preparation and characterization of polyurethane rubber/polypropylene-based thermoplastics vulcanizates nanocomposites with succinic anhydride intercalated layered double hydroxide

Abstract

Herein, a novel polypropylene/polyurethane rubber (PP/PUR) was prepared based on thermoplastics vulcanizates (TPV)/layered double hydroxide (LDH) nanocomposite in the presence of 3-(triethoxysilyl)propylsuccinic anhydride (SSA) intercalated LDH (SSA-LDH). The effect of SSA-LDH was explored on thermo-mechanical, thermal, morphological, rheological, and mechanical properties as well as gel content, compression set, X-ray photoelectron spectroscopy analysis, and cross-linking density (CLD) of TPV based on PP/PUR with the weight ratio of 40/60. It was found that the crystallization, tensile strength, gel content, cross-linking density, young’s modulus, elongation at break, melting point, and damping factor significantly changed with increasing SSA-LDH content in PUR/PP TPVs. The reasons could be attributed to cross-linking induced by SSA-LDH and curing agent Bis-(triethoxysilylpropyl) tetrasulfide (also called (Si-69)) that grafted onto PUR chains, resulting in good dispersion of fine PUR vulcanized particles into PP matrix. This claim was confirmed by studying the rheological properties through Rheometeric mechanical spectroscopy and dynamic-mechanical analysis. Field emission scanning electron microscope images confirmed the improved compatibility between PUR and PP by adding SSA-LDH. The gel content and CLD of TPV samples without SSA-LDH were 20% and 2.75 mol/mL, respectively, which showed a significant increment to 25.5% and 4.5 mol/L upon adding 5 wt. % SSA-LDH. The highest elongation at break, tensile strength, and young’s modulus were 525%, 16.5 MPa, and 210 MPa, respectively which were observed for TPV5.