Impact of amber powdered waste on the processability and properties of PCL-based materials

It is the first comprehensive study showing the effect of amber particles in a biodegradable polymer matrix. The effect of amber powdered waste (AbW) on poly(epsilon-caprolactone) (PCL) processing was evaluated, along with the influence of different processing methods on the structure and properties of the PCL/AbW systems. AbW was melt-mixed with PCL in proportions of 1 %, 2.5 %, or 5 % wt, without the use of any compatibilizer. Following the twin-screw extrusion mixing, the composites were further processed using injection molding or cast-film extrusion. The materials obtained were tested for processing properties (melt flow rates, density), morphology (scanning electron microscopy), chemical composition (infrared spectroscopy), thermal properties (differential scanning calorimetry, thermogravimetry, Vicat softening temperature, and heat deflection temperature), strength (static tensile test, flexural test, hardness, and impact strength) and surface properties (contact angle). The addition of amber to PCL did not require changes to the parameters of subsequent processing. The interactions between the low-molecular weight compounds from AbW and the matrix appear more significant than any potential degradation of the polymeric chain during processing. Regardless of the processing method, the PCL/AbW system exhibited strong interfacial bonding while maintaining the ductile nature of the PCL matrix. The addition of 1 % and 2.5 % AbW enhanced the reinforcement and strengthening of the composites. Nevertheless, the addition of 5 % AbW resulted in lower mechanical performance and increased heterogeneity in thermal events. Amber powdered waste from the jewelry industry appears to be a promising sustainable filler and compatibilizer for PCL, while also potentially adding biological functionalities.