Natural Rubber/High Cis Butadiene Rubber-Filler Interactions And Rheological Properties In Rubber Airbag Compounding Formulation

The rheological properties of rubber compound in general application and especially rubber airbag compounding is very important to predict the mechanical properties of rubber products, as well as useful for obtaining optimum formulations in the research and development of a product. The viscoelastic properties of the rubber compound are strongly influenced by the type of rubber and the filler used. The purpose of this research is to investigate the rheological properties of rubber airbag compounding using natural rubber (NR) and high cis butadiene rubber (BR) materials with various compositions of carbon black N220 filler. The mixing of NR and BR with 90/10 phr ratio was performed in a kneader, with carbon black N220 filler variation: 35, 45, 50 phr, named as BD1, BD2 and BD3, respectively. Rheology and viscosity properties were tested using Rubber Process Analyser (RPA) 2000 Alpha Technology. The test was performed with strain sweep at 70 C and comparing 1% strain and 10% strain to indicate dispersion and homogenity. Frequency sweep was performed at 100 C at 6 cpm and 7% strain.  High strain sweep was also done as well as strain sweep after cure (ASTM D6601) which material were cured at 1800 C and strain sweep was applied at 1%, 2%, 5%, 10% and 20% to determine the mechanical properties of compound. The result showed that 35 phr of carbon black N220 (BD1) was the optimum formulation since compounds BD3 and BD2 have higher elastic torque (S’) peaks and may be harder to process as a result. The results for Tan (Delta) from all compounds in the high strain sweep verify that compounds BD3 and BD2 have lower Tan(Delta) values and therefore will probably have more difficulty in processing. The highest peak of modulus values at low strain indicates the carbon black with the highest reinforcement or the worst dispersion. BD3 and BD2 have high peak modulus value which is show the worse dispersion compared to BD1. Keywords: rheology, rubber airbag, filler, RPA