1H MRI of liquid ingress into polymers

Complete an 12 page literature review how MRI has been used to study liquid ingress into polymers with a focus on non-swelling systems but showing an appreciation of swelling systems as well. This should also include a section on MRI theory and what is meant by quantitative measurements, i.e. how a NMR relaxation effects taken not account. The review should be a technical one focusing on the types of MRI techniques used and what information can be gleans from them. How is the diffusion front coefficient extracted and how does this differ from the del-diffusivity, i.e. Fickian flux diffusion versus molecular self-diffusion. The review should also include a section on the importance of characterising T1 and T2 relaxation time constants so that quantitative results can be obtained from the 1H MRI images. If there is literature on HDPE or thermoplastics give more emphasis on it.