Investigation of the rheological an‎d mechanical properties of polypropylene/polylactic acid alloy filled with aragonite calcium carbonate

10/20/2026 12:00:00 AM

In this research, the optimization of mechanical an‎d rheological properties of polypropylene (PP)/polylactic acid (PLA) alloy filled with precipitated aragonite calcium carbonate was conducted, focusing on determining the optimal composition of components an‎d comparing different filler grades. Initially, the optimal ratio of base polymers was determined by examining an‎d analyzing the results of mechanical tests including tensile strength, elastic modulus, an‎d impact strength of various PP an‎d PLA blends, where the composition of 70% PP an‎d 30% PLA was selec‎ted due to its superior mechanical properties (tensile strength an‎d toughness). In the next stage, the optimal amount of maleic anhydride (MAH) compatibilizer was investigated, an‎d 5% was identified as the optimum amount. Then, the optimal amount of uncoated precipitated aragonite calcium carbonate (grade 9021) was determined by adding different levels of this filler to the blend an‎d analyzing its mechanical an‎d structural behavior, where 30% of this mineral created a desirable balance between increased stiffness an‎d preservation of toughness an‎d ductility in the alloy. Finally, using the optimal formulation consisting of 70% PP, 30% PLA, 5% compatibilizer, an‎d the optimal 30% calcium carbonate, one ground calcium carbonate (GCC) grade an‎d four precipitated calcium carbonate (PCC) grades with different surface coatings (such as tetrabutyl titanate an‎d stearic acid) were compared with each other. By examining tensile an‎d impact properties, grade 543 with titanate coating, having a tensile strength of 29.2 MPa an‎d impact strength of 16 J/m, offers higher tensile strength an‎d toughness compared to the GCC grade an‎d uncoated PCC due to its finer particles an‎d more uniform dispersion. Additionally, thermal resistance results showed that grade 543 with a Vicat softening temperature of 156 °C has better thermal stability than grade 132, which is attributed to its uniform dispersion an‎d finer particle size. SEM images confirmed that grade 543, with the finest particle size an‎d the highest coating level, exhibits the least particle agglomeration, resulting in a denser an‎d stronger reinforcing network. Rheological analysis results indicated that the MFI value in grade 152 with stearic acid coating was 17.9 g/10 min, which is due to the stearic acid coating acting as an external lubricant. Furthermore, loss modulus results showed that grades 543 an‎d 132 exhibited a 75% increase compared to grade 152, demonstrating the superiority of titanate coating over stearic acid coating.

كربنات‌كلسيم آراگونيت , پلي‌لاكتيك اسيد , پلي‌پروپيلن , پركننده

Aragonite Calcium Carbonate , Polylactic Acid , Polypropylene , filler

Mohamad Naghiei

Dr. Fasihi