Sintesis dan Karakterisasi Paduan LDPE/EPDM dengan Bahan Pengisi Serbuk Tanah Liat sebagai Peredam Benturan Pintu Kendaraan

Abstract

A composite study was conducted using a blend of LDPE/EPDM with the addition of clay powder as a filler, applied as an impact absorber for vehicle door seals. The manufacturing process involved mixing LDPE plastic with synthetic rubber EPDM, using a compatibilizer, and vulcanizing the mixture by adding stearic acid, ZnO, MBTS, sulfur, and varying the filler content of clay powder at ratios of 5 phr, 10 phr, 20 phr, 30 phr, and 40 phr. The mixture was then hot-pressed at a temperature of 185°C. The optimum final result was obtained at an LDPE/EPDM to clay powder ratio of 80:20:20 phr, achieving a tensile strength of 18.26 MPa before aging, which meets the Indonesian National Standard (SNI, 1989) for rubber seals in motor vehicles, and 17.90 MPa after aging. The elongation value increased from 30.18% before aging to 37.94% after aging. The modulus of elasticity decreased from 60.50 MPa before aging to 47.22 MPa after aging. The impact test showed the highest value at 15,687.25 J/m². The optimum LDPE/EPDM specimen with added clay powder was further analyzed using FTIR, SEM, and TGA. FTIR analysis showed no significant changes between LDPE, EPDM, and the addition of clay powder, except for a new functional group at a wavenumber of 842 cm⁻¹, corresponding to Si–OH from the clay powder. SEM analysis revealed a homogeneous morphology, although some agglomeration was observed due to the nature of the filler and the mixing method. Thermal analysis (TGA) indicated decomposition occurred at temperatures between 484.50°C and 533.75°C, with a total mass loss of 81.035%.