Structure and performance properties of environmentally-friendly biocomposites based on poly(-caprolactone) modified with copper slag and shale drill cuttings wastes

Highlights: • Copper slag and shale drill cuttings wastes were applied as fillers for PCL matrix. • Structure-property relationships of biocomposites were examined. • TVOCs as function of waste filler characteristics and content were evaluated. • Biocomposites showed no toxic effect towards studied bacterial strains. • PCL modified with low-cost fillers can be considered as environmentally-friendly. The potential application of two types of industrial wastes, drill cuttings (DC) and copper slag (CS), as silica-rich modifiers of poly(-caprolactone) (PCL) was investigated. Chemical structure and physical properties of DC and CS fillers were characterized using X-ray diffractometer, X-ray fluorescence spectroscopy, particle size and density measurements. PCL/DC and PCL/CS composites with a variable content of filler (5 to 50 parts by weight) were prepared by melt compounding in an internal mixer. It was observed that lower particle size of DC filler enhanced processing of biocomposites comparing to CS filler. Smaller particles of DC filler and thus the higher specific surface area, enabled better encapsulation of filler by polymer chains, hence lower porosity and consequently higher tensile properties comparing to PCL/CS biocomposites. It was noticed, that the impact of waste filler characteristics on tensile properties became negligible at higher loadings. This indicates weak interactions between waste filler and PCL matrix, due to aggregation of filler particles and formulation of voids in phase boundary. This phenomenon was confirmed by scanning electron microscopy, headspace analysis and thermogravimetric analysis. Microbial tests revealed that prepared biocomposites show no toxic effect towards analyzed bacterial strains, therefore could be considered as environmentally-friendly.