Manipulation of dermis based collagen networks with engineered mechanical behaviour for applications in the tanning sector

In this thesis, technologies and processes of the biomaterial field, were implemented in the tanning sector, in order to obtain leather prototypes having engineered mechanical properties such as tear resistance and elastic recovery. The work is basically divided in two parts. First, the characterization of conventional leather material is reported and it is aimed at defining the benchmarks to which the chemical physical parameters of the engineered products need to be compared. The obtained results provided information on the structure-composition-functions relationship of animal skin and most importantly they provided clear hints on how to modify the substrate and in what step of the tanning process this is most convenient. Second, the identification of materials and the chemical†"physical strategies is disclosed. Materials and processes were studied in order to most effectively affect the macroscopic properties of the final product. Then, the chemical-physical characterization of the obtained engineered samples is reported. Finally, tanning process was performed in order to realize engineered prototypes. Two manipulation strategies were implemented: crosslink and reinforcement. Crosslink involved the use of high temperature while reinforcement was carried out selecting polymeric materials to be delivered within dermis. In particular, polydimethylsiloxane and nylon were selected in order to increase tear resistance while elastomeric materials were selected in order to improve elastic recovery. Good prototypes were obtained using PDMS and Elastollan as elastomeric polymer. In particular increase of tear resistance were higher of 30% and improvement in the elastic recovery was found obtaining a decrease of 20% for the permanent strain values.