Analysis of the fracture of the PLA/20µHAp specimen (Figure , 10A') shows similar conclusions to the morphology analysis in section 3.1. The excellent adhesion of the HAp filler particles to the PLA matrix is evident. The particles were so strongly anchored in the matrix that, as can be seen in the images, some of them broke within their volume during the stretching process without losing their interaction with the polymer. This composite is much more brittle than the pure matrix, as evidenced by the reduction in strain at break. The material is also weaker in terms of tensile strength (43 % lower than for PLA). On the other hand, the strong interactions of HAp with the polymer matrix allowed a significant increase in the modulus elasticity (by about 30 %) . The fracture image of the PLA/20nHAp specimen (D, D') also confirms the previous observations. Strong PLA-HAp interactions and good dispersion of the nanoparticles in the material lead to improved mechanical parameters compared to the material with µHAp. In addition to the modulus of elasticity, which remains at a similar level, tensile strength and elongation at break have been improved.