Magnetic resonance imaging studies of diffusion in polymers

Area of Science:

• Polymer Science
• Materials Science
• Food Packaging Technology

Background:

• Substance migration from polymers into food is influenced by penetrant uptake into the packaging.
• Accurate predictive models for migration require understanding food penetration mechanisms into packaging materials.
• Food packaging safety necessitates quantifying the interaction between food simulants and polymers.

Purpose of the Study:

• To investigate the mechanism of food simulant penetration into polymer packaging.
• To utilize Magnetic Resonance Imaging (MRI) for quantitative analysis of penetrant uptake.
• To explore polymer-penetrant molecular interactions and diffusion characteristics.

Main Methods:

• Magnetic Resonance Imaging (MRI) was employed to quantitatively measure the uptake of simulants into polymers.
• Gravimetric uptake data were used for validation of MRI measurements.
• Pulsed Gradient Spin Echo (PGSE) technique combined with MRI provided spatially resolved diffusivity measurements.

Main Results:

• MRI-measured uptake of simulants into low-density polyethylene showed good agreement with gravimetric data.
• Penetration rates of olive oil and isooctane into polyethylene varied with temperature.
• Significant differences in isooctane ingress rates were observed across various commercial polyethylene samples.
• Spatially resolved penetrant diffusivity within the polymer was measured as a function of penetrant volume fraction.

Conclusions:

• MRI is a valuable tool for quantitative assessment of penetrant uptake in polymer packaging.
• The study provides insights into polymer-penetrant interactions and diffusion dynamics.
• Findings will aid in developing improved predictive models for substance migration in food packaging.