Study On Rupture Properties Of Oil-swellable Elastomers

Oil-swellable elastomer is a kind of rubber materials which can absorb solvent molecules and lead to the volume expansion when exposed to organic solvent.In recent years,oil-swellable elastomers have been explored to make swellable packers in oil industry,which have many advantages over traditional cement packers.In the practical applications,the elastomers absorb solvent and swell against the confinement,which can seal zones in the borehole and have broad application prospects.The swollen elastomers are usually subjected to large pressure difference,which can cause fracture of the elastomers.In this paper,we conduct experimental studies and theoretical predictions of the rupture behavior of the swellable elastomers.The material used in the experiment is an oil-swellable elastomer,named as styrene butadiene rubber(SBR)and swelled in hexadecane.This combination of elastomer and swelling agent can be considered representative of oilfield applications.Fracture energy criterion is employed to describe the rupture behavior of swellable elastomers.Pure-shear test is selected to measure the fracture energy of the swollen SBR.Different stretch rates and different swelling ratios are considered.It is found that at the same tensile rate,both the stretch at rupture and the fracture energy of materials reduce significantly with the increasing of the swelling ratio.Furthermore,at the same swelling ratio,the fracture energy increases with the increasing of the tensile stretch rate.Based on the pure-shear test,the shear moduli of SBR in different swelling ratios are obtained by fitting the nominal stress-stretch data.It is mentioned that the neo-Hookean model is employed.Using the measured fracture energy from pure-shear test,the stretches at rupture of SBR in different swelling ratios for simple extension test are predicted theoretically.Compared to the experimental data,it can be seen that the relative error is less than 2%.The agreement verifies that the fracture energy of oil-swellable elastomers measured from pure-shear test can be treated as a mechanical parameter of the swollen SBR,which is independent of loading conditions and geometrical parameters.