Work

Comparative Study on the Rheological Properties of PS/PP–CaCO3 and PS/PP–Walnut Shell Blends

Year: 2025

Type: article

Abstract: This study presents a comparative rheological analysis of polystyrene/polypropylene (PS/PP 20/80) blends filled with either calcium carbonate (CaCO3) or walnut shell powder at 8 and 12 wt.% loadings. Rheological properties were investigated using a capillary rheometer at temperatures ranging from 190°C to 220°C. The results demonstrate that adding CaCO3 significantly increases shear stress, apparent viscosity, and flow activation energy (up to 12.9 kJ/mol), enhancing rigidity but impairing processability. In contrast, walnut shell composites exhibited a lubricating effect, reducing viscosity by 15–20%, increasing the melt flow index, and lowering the flow activation energy, thereby promoting easier flow. This is attributed to the thermal softening of lignocellulosic components. The optimal balance for processability was achieved with 8% walnut shell at 220°C, while 12% CaCO3 is recommended for applications requiring higher stiffness. These findings underscore the potential of walnut shell as a sustainable, processability-enhancing filler, presenting a clear trade-off between improved flow and mechanical reinforcement. KEYWORDS Agricultural waste, capillary rheometry, melt viscosity, polymer composites, processability enhancement, shear thinning

Source: Scientific Journal of King Faisal University Basic and Applied Sciences

DOI: 10.37575/b/sci/250033

Authors: Rama AL Jobarani, Douaa Alsaeed, Fawaz Deri, Mhd Alkurdi

Institution: Damascus University

Language: English

Topic: Natural Fiber Reinforced Composites

Subfield: Polymers and Plastics

Field: Materials Science

Domain: Physical Sciences

SDG: Responsible consumption and production

Open Access status: bronze

Funder: Damascus University