Pressurized in-situ dynamic mechanical thermal analysis method for oilfield polymers and composites

Abstract

Oilfield downhole equipment uses engineered polymers and composites extensively in various operations. The capability of polymers and composites to resist high temperature in downhole hot-wet fluid and gas environment is critical. Dynamic mechanical thermal analysis (DMA) is known as the best analysis technique to determine this capability represented by glass transition temperatures (Tg) of polymeric materials. However, current commercially available DMA analyzers are commonly designed to perform a temperature sweep in a dry atmosphere-even for wet Tg determination of exposed wet samples, where a drying process associated with the analysis gives inaccurate results. Some recent DMA analyzers are equipped with an immersing test fixture; however, they are opened to ambient pressure with a low uppertemperature limit. There is no pressurized DMA analyzer commercially available. This study presents an innovative and unique pressurized DMA analyzer using an in-house-developed HPHT in-situ mechanical testing system. The analysis can be conducted for a polymer or composite specimen in an immersed fluid condition up to 260 °C and 70 MPa under 3-point bending, compression and tension dynamic modes. This in-situ DMA method can determine accurately the dry and wet Tgs for polymers and composites and the true DMA curves in an immersed wet condition. Hydrostatic pressure-dependent Tgs of ABS and PEEK polymers were also determined up to 69 MPa.