Researchers in Slovakia have shown that the paper layer from used drink cartons can be milled into a cellulose powder and used as a partial replacement for carbon black in natural rubber. The work, published in the Journal of Materials Science, tested the material at five parts per hundred rubber and combined it with kaolin in hybrid formulations. Mixing torque dropped by more than 20 percent in one blend, and curing time fell by over 34 percent, both of which point to lower energy use in rubber processing. Mechanical properties shifted as expected: tensile strength dropped by 7 to 18 percent depending on the blend, while elongation at break improved, from about 258 percent to 311 percent in the best case. That makes the material more interesting for seals, hoses, and mats than for tires. The authors also used positron annihilation spectroscopy to show how the filler changed the polymer structure at the nanoscale. The broader point is that carton waste, which is hard to recycle because of its plastic and aluminium layers, can be processed with simple mechanical milling rather than chemical pretreatment. Every kilogram of carbon black displaced means less fossil feedstock and lower process emissions. The remaining hurdles are feedstock consistency, long-term durability, and cost validation at scale.
