(325d) High Speed Friction Grinding of Thermoplastics Assisted By Food Gums

High speed friction grinding (fibrillation technology) has been used to grind plant in water but never been explored for grinding of thermoplastics. Its most common use is for converting cellulose pulp into nanofibrillated cellulose. Thermoplastics like polylactic acid (PLA), low and high density polyethylene (LDPE and HDPE) and polypropylene (PP) are hydrophobic and elastic in nature that make them difficult to fracture into fine powders at room temperature. This study examines a new concept involving use of food gums for grinding of thermoplastics into finely ground particles in an environmental friendly and cost-effective way. Low concentrations of food gums (like 0.5% guar gum in water) made such grinding possible as they increased the viscosity of water which reduced the settling of plastics and increased the residence time through the grinder. Tensile, flexural and impact strengths of the plastics were studied and higher grinding efficiency of PLA could be explained by its low elongation-at-break compared to LDPE, HDPE and PP. The microplastics (2000-45 µm) were studied for mass and particle size distributions and by SEM, 13C CP/MAS NMR, FTIR, DSC and TGA. Viscosity of guar gum and contact angles were measured. This new technology can produce finely ground microplastics (710–45 µm) for a variety of applications such as additive manufacturing, plastic coating on metal substrates, biomedical devices, upcycling and recycling.

Reference:

Bhagia, S, Gallego, NC, Hiremath, N, et al. Fine grinding of thermoplastics by high speed friction grinding assisted by guar gum. J Appl Polym Sci. 2021;e50797. https://doi.org/10.1002/app.50797