*Article* **Essential Work of Fracture and Evaluation of the Interfacial Adhesion of Plasticized PLA/PBSA Blends with the Addition of Wheat Bran By-Product**

**Laura Aliotta 1,2,\* , Alessandro Vannozzi 1,2, Patrizia Cinelli 1,2,3 , Maria-Beatrice Coltelli 1,2,\* and Andrea Lazzeri 1,2,3**

<sup>1</sup> Department of Civil and Industrial Engineering, University of Pisa, 56122 Pisa, Italy;

alessandrovannozzi91@hotmail.it (A.V.); patrizia.cinelli@unipi.it (P.C.); andrea.lazzeri@unipi.it (A.L.)

<sup>2</sup> National Interuniversity Consortium of Materials Science and Technology (INSTM), 50121 Florence, Italy


**Abstract:** In this work biocomposites based on plasticized poly(lactic acid) (PLA)–poly(butylene succinate-*co*-adipate) (PBSA) matrix containing wheat bran fiber (a low value by-product of food industry) were investigated. The effect of the bran addition on the mechanical properties is strictly correlated to the fiber-matrix adhesion and several analytical models, based on static and dynamic tests, were applied in order to estimate the interfacial shear strength of the biocomposites. Finally, the essential work of fracture approach was carried out to investigate the effect of the bran addition on composite fracture toughness.

**Keywords:** biocomposites; natural fibers; poly(lactic acid) (PLA); fracture mechanics
