Curing, thermal, tensile and flammability characteristics of sepiolite/ethylene propylene diene monomer rubber composites with glut palmitate salt and silane coupling agents

Abstract

AbstractThe main objective of this work is to compare the effectiveness of a newly synthesized glut palmitate (GP) salt and a commercially available (3‐aminopropyl) trimethoxysilane (APTMS) as coupling agents in sepiolite (SEP) filled ethylene propylene diene monomer (EPDM/SEP) composites. The unmodified and modified composites with different amounts of SEP were prepared with an open two‐roll mill and the morphology, cure characteristics, tensile properties, flammability, and thermal stability were studied. Fourier transform infrared spectroscopy (FTIR) analysis indicated shifting of the related absorption peaks and confirmed the interaction between composite with the GP salt and APTMS and the successful modification of sepiolite particles in EPDM/SEP composites. The maximum torque (MH), scorch time (ts2) and cure time (t90) of the modified EPDM composites decreased with both coupling agents. Thermal stability reduced in the presence of coupling agents but the reduction is more pronounced in the composite with GP salt due to low‐temperature degradation of the fatty acid. Compared with unmodified EPDM/SEP, the tensile strength of the modified EPDM/SEP with GP and APTMS enhanced by 15% and 52%, respectively but both elongation at break and modulus were lowered. GP and APTMS were efficient coupling agents in linking the SEP and EPDM matrix, reducing the rubber‐filler interaction (Qf/Qg) from 1.00 for the EPDM/SEP composites to 0.76 and 0.64 for the EPDM/GP/SEP and EPDM/APTMS/SEP composites, respectively.