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[Summer series] Julie Diani - Fully Inflated

Julie Diani, research scientist of the Solid Mechanics Laboratory at École Polytechnique, works on modeling the mechanical behavior of polymers.

©Silvère Leprovost

“It takes small steps to make great discoveries possible,” says Julie Diani. In 2016, the research scientist joined the Solid Mechanics Laboratory at École Polytechnique to develop and structure her activity around polymers and nanocomposites.

Her work on modeling the mechanical behavior of polymers earned her international recognition, marked first by the publication of her study of shape memory polymers published in the International Journal of Plasticity and subsequently, in 2015, by the Sparks-Thomas Award she received from the American Chemical Society for her research on elastomers. Now a recognized researcher in this field, nothing predestined Julie Diani to the study of these materials. The daughter of two math teachers, Julie Diani always loved the discipline and enjoyed solving equations that seemed like amusing enigmas to her. They provide her with a form of adversity that enables her to surpass herself which she also finds in competitive sports: she has trained with professionals at the Insep judo club and practices biking on the Tour de France course.

After graduating from École Normale Supérieure Cachan, Julie Diani completed a PhD on the behavior of elastomers. In a lab whose only equipment consisted in computers, the postgraduate student modeled elastomer behavior that she programed using computer tools. “For three years, I did my research without ever handling materials,” she says about something that she finds astonishing to this day. After this purely theoretical thesis, the researcher began conducting experimental research as well. “Gradually, I’m finding a balance between modeling and experimentation in defining the properties of the materials I study,” she states.

Since her arrival at l’X, she has been pursuing the research initiated fifteen years ago on the Mullins effect. This phenomenon describes the change in the behavior of elastomers undergoing repeated stretching, “a little like when a balloon is inflated and it is easier to deform it the second time,” she explains. On this subject, the researcher collaborates with tire manufacturers interested in her progress. She has now expanded her research to highly filled elastomers, such as propellants used in rockets. “We want to be able to predict the appearance of defects, occurring during the storage or transport of these materials, which could impair combustion,” says the Director of Research, supported in this work by manufacturers in the defense industry.

Find all the portraits of researchers of our summer series, here.