This study investigates the morphological and physical/end-use properties of corn cob powder-filled recycled polypropylene composites. The composites were prepared by incorporating corn cob powder of particle sizes 150 µm, 300 µm and 425 µm respectively at filler loadings of 5 to 25 wt%. The properties were determined according to standard test procedures. Results showed that the incorporation of corn cob powder as filler resulted to enhancement of water absorption and solvent sorption, which were found to increase with both increase in filler loading and increase in filler particle size, probably due to the hydrophilic nature of corn cob powder. It was also discovered that solvent sorption was most pronounced with benzene, followed by toluene and lastly xylene, in accordance with the relative proximity of their solubility parameters to that of polypropylene. Flame propagation rate was also found to improve by the incorporation of corn cob powder due to its high content of cellulose, a combustible organic matter. However, specific gravities of the composites were found to be lower than for the unfilled polypropylene, an implication that the composites produced are lighter in weight than the unfilled. Specific gravity increased with increase in filler loading but decreased with increase in particle size. The Morphological studies showed increase in the number of spherulites with increase in filler loading and increase in the size of the spherulites with increase in particle size. Further observation showed that the particle sizes and pores sizes detected increased with increase in filler particle size probably due to poor interaction and distribution of coarse particles. It is hoped that this present study will to help place the usefulness of corn cob as filler in the development of thermoplastic composites in future and develop its niche in the scientific record.

Abstract. This study investigates the morphological and physical/end-use properties of corn cob powder-filled recycled polypropylene composites. The composites were prepared by incorporating corn cob powder of particle sizes 150 µm, 300 µm and 425 µm respectively at filler loadings of 5 to 25 wt%. The properties were determined according to standard test procedures. Results showed that the incorporation of corn cob powder as filler resulted to enhancement of water absorption and solvent sorption, which were found to increase with both increase in filler loading and increase in filler particle size, probably due to the hydrophilic nature of corn cob powder. It was also discovered that solvent sorption was most pronounced with benzene, followed by toluene and lastly xylene, in accordance with the relative proximity of their solubility parameters to that of polypropylene. Flame propagation rate was also found to improve by the incorporation of corn cob powder due to its high content of cellulose, a combustible organic matter. However, specific gravities of the composites were found to be lower than for the unfilled polypropylene, an implication that the composites produced are lighter in weight than the unfilled. Specific gravity increased with increase in filler loading but decreased with increase in particle size. The Morphological studies showed increase in the number of spherulites with increase in filler loading and increase in the size of the spherulites with increase in particle size. Further observation showed that the particle sizes and pores sizes detected increased with increase in filler particle size probably due to poor interaction and distribution of coarse particles. It is hoped that this present study will to help place the usefulness of corn cob as filler in the development of thermoplastic composites in future and develop its niche in the scientific record.

This study modeled some mechanical properties of clay powder filled recycled low-density polyethylene, rLDPE (rLDPE composite). The rLDPE is commonly referred to as used sachet water bags. The clay powder (filler) was obtained by sun-drying, grinding, and sieving. Two particle sizes of clay powder were used: −90 µm and −425 µm to represent the passing sizes at different clay powder contents of 5, 10, 15 and 20 wt% which were thoroughly mixed with the recycled low-density polyethylene in an injection molding machine at 173˚C. The results showed that the tensile strength, tensile modulus, hardness, flexural strength, fatigue strength and hardness increased with increase in clay powder contents. However, there were decreases in strain-at-breakage and shear strength as clay powder content increased. Model equations showed that smaller particle size enhanced the mechanical properties and equations generated can be used to predict the properties of composites at predetermined clay contents. Standard deviations obtained for the various mechanical properties show that the model, in most cases had the lowest degree of scatter (dispersion) than those of −90 µm and −425 µm. Hence, these models are suitable to predict outcomes of the properties of the clay filled recycled low-density polyethylene composites.

Polymer composites are increasingly replacing metals in structures such as gears, wheels, clutches, housings, bushings and other areas where tribology is of great importance. Various ways are used to improve the tribological behaviour of neat polymers, and the most familiar method is the incorporation of fibres/fillers in the polymer to produce composites. In this present research, the tribological behaviour of periwinkle shell powder-filled recycled polypropylene composite was studied. Injection moulding was used for the preparation of the composites and the impact strength, wear resistance and fatigue strength were examined. SEM was utilized to support the discussion of the results. The results showed that the incorporation of periwinkle shell powder into polypropylene improved the wear resistance and fatigue strength but showed no improvement in impact strength.