Enhancing Compound Properties and Aging Resistance by using Low Viscosity HNBR (Paper No. 34)

摘要

Recent advances in HNBR, technology have led to the development of low mooney viscosity (39 MU, ML1+4@100°C), easy to process HNBR polymers. Compounds based on the low mooney viscosity HNBR polymer have shown improved mixing characteristics (faster black incorporation time, lower mix temperature) and excellent processing characteristics (faster extrusion rates, shorter injection times, lower pressure). Furthermore, the narrower molecular weight distribution gives rise to better mechanical properties.The 39 MU low viscosity HNBR grade contains 34% acrylonitrile and has been hydrogenated to less than 0.9% residual double bond content. This grade has been developed for applications where improved compound flow is particularly beneficial: wire and cable, oil well industry, as well as, automotive applications (seals, gaskets and hoses). In addition to the excellent processing characteristics, the new low viscosity polymer enables the use of known compounding technologies that might otherwise be excluded because of processing limitations.A screening experiment has been carried out to study the influence of five factors; added silicate filler, plasticizer level, antidegradant system, metal oxide and HNBR polymer viscosity, on the compound pVoperties. The choice of polymer was found to be a statistically significant variable in many of the properties related to processing. The compound viscosities covered a large range; from a low of about 44 MU to a high of 125, while the compound scorch safety is doubled between worst and best case combinations. In general, the compound physical properties are not highly dependant on the polymer viscosity but are more dependant on filler, plasticizer and antidegradant selection. The availability of the new low viscosity HNBR polymer has enabled alternate compounding techniques that have been previously excluded due to high compound mooney viscosity and other significant processing considerations.