Structural biodegradable biocomposites based on Pistacia vera endocarp for rigid laminates in sustainable stationery: optimization via robust design and alignment with the circular economy and Earth-centered regenerative design.

This research project addresses the design, physical manufacturing, and experimental characterization of a novel rigid two-dimensional biocomposite material, conceived as an ecological and low-environmental-impact alternative for the corporate and auxiliary stationery sector. Driven by the need to substitute synthetic polymers and optimize forest resources, a ternary matrix was developed that valorizes agro-industrial waste from pistachio shells (Pistacia vera) as structural reinforcement, in synergy with recycled cardboard fibers and a biodegradable binder phase based on gelatinized starch from cassava root (Manihot esculenta, commercially known as tapioca). The research proposes a multifactorial experimental design that evaluates the influence of two critical variables on the final performance of the laminate: the relative proportion of the three components and the particle size distribution of the pistachio reinforcement, classified into three distinct fractions: a powder-type size, a controlled fine size (, and a larger irregular particle size. By dispensing with three-dimensional computer simulations (CAD/FEA) due to the two-dimensional and empirical nature of the proposal, the validation of the material was structured through a physical, mechanical, and dynamic laboratory characterization protocol. The selected tests comprise: Three-point bending test (ASTM D790): to determine the elastic modulus, deflection, and maximum breaking load under orthogonal bending stresses. Total immersion water absorption test (ASTM D1037): focused on quantifying the hygroscopicity, weight gain, and dimensional stability of the starch and cardboard matrix against moisture. Falling dart impact test (ASTM D1709): applied to calculate toughness and dynamic energy dissipation capacity in Joules according to the shell particle size.