Effect of the thermoplastic types and ratios for the 3D printed thermoplastic natural rubber vulcanizates: Mechanical, dynamical, thermal, printed-structural properties

Since the crosslinked natural rubber (NR) products contain chemical crosslinks, the materials have loosened the biodegradable and environmentally friendly properties. Combination of NR and thermoplastic, so called thermoplastic natural rubber (TPNR), can be a proper approach for solving this evident through new technological processing. Therefore, the three-dimensional 3D printing TPNR based on polypropylene (PP) and high-density polyethylene (HDPE) thermoplastics were carried out. Blending ratios of 70:30 and 80:20 have investigated, while the dynamically cured system was applied to the blends. This aims to the NR applications and solves the end-cycled of NR waste which cannot be recycled. Relating the molecular structure of the blends, the crosslinked NR particles are dispersed and distributed in the PP phase, while the superior toughness of HDPE provides high elongation at break and impact strength. However, the high crystallinity of PP combined with its low toughness and high stickiness makes it a more broadly applicable 3D printing material than HDPE. It was found that the complexed 3D printing of PP/NR at 80:20 showed the highest compressive strength relative to pure PP. This indicates the improvement of the intrinsic properties of the blends. This improvement can be advantageous for the NR product platform when it is incorporated in PP and parts are produced by 3D printing.