Conversion of polystyrene foams into auxetic metamaterials

Auxetic foams have gained popularity within the research community because of their enhanced properties, such as low density combined with high relative stiffness, toughness, and damping properties. Low polystyrene (PS) are commonly used in packaging industry, but a short service life generate volume waste (white pollution). This is why recycling valorizing necessary imperative. The objective this work to present simple environmentally friendly process combining pressure (vacuum) mechanical compression convert recycled PS (15 kg/m3) into (50–63 having negative tensile compressive Poisson's ratios (NPR). effect processing conditions (vacuum level, temperature, pressure, time) were studied. Based on optimized conditions, ratio resulting auxetic reached −0.65 for Y direction (width) −0.74 Z (thickness) when stretching X (length). On other hand, minimum −0.32 −0.28 direction. foam structure was characterized via morphological analysis determine changes after treatment. Finally, properties (Young's modulus, strain energy, energy dissipation, capacity) also discussed. It observed that improved compared original (PS-O) terms resilience strength. For example, elongation at break (31%–62%) much higher PS-O (7%). These can be several applications, sports military protective equipment.