Compatibility of Dimethyl Ether (DME) and Diesel Blends with Fuel System Polymers: A Hansen Solubility Analysis Approach

The compatibility of notable infrastructure elastomers and plastics with DME and its blends with diesel fuel were examined using solubility analysis. The elastomer materials were fluorocarbon, acrylonitrile butadiene rubber (NBR), styrene butadiene (SBR), neoprene, polyurethane and silicone. Plastic materials included polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyoxymethylene (POM), polybutylene terephthalate (PBT), polypropylene (PP), high density polyethylene (HDPE), along with several nylon grades and thermosetting resins. These materials have been rigorously studied with other fuel types, and their volume change results were found to correspond well with their predicted solubility levels. A Hansen solubility analysis was performed for each material with DME, diesel, and blends of both fuel components. The results for the elastomers indicate that DME and its blends with diesel fuel will offer improved compatibility with NBR and SBR materials. Silicone, neoprene and polyurethane show similar solubility potential for any combination of DME and diesel, so no degradation is expected with DME. In contrast, fluorocarbon can be expected to become increasingly incompatible with increased DME concentration. In general, the solubility analysis also indicated that many of the plastic materials can be expected to have good to excellent compatibility with DME and its blends with diesel fuel. The analysis also indicated that polyester resins should exhibit high solubility (and therefore high swelling) in both diesel and DME. However, previous empirical results showed that this result was not an accurate reflection of polyester resin performance in diesel fuel.