Thermomechanical degradation of bio-composites based on polybutylene succinate and brewer spent grain

Polybutylene succinate (PBS) is a semi-crystalline, compostable and biodegradable thermoplastic biopolymer, obtainable from renewable sources. It is considered an excellent substitute for traditional fossil-based plastics such as polyethylene. It can be mixed with agro- food waste, such as spent brewer's grains (BSG), to produce new biocomposites (PBS/BSG) with the aim of reducing the consumption of virgin biomass, reducing the use of fossil-based polymers, using agro- food waste that must be disposed of anyway. BSG is in fact an unused, free and widely available resource. In this research, the resistance to thermomechanical degradation that occurs in thermoplastic polymers during melt transformation operations by extrusion, static mixing, thermoforming, etc. was evaluated. PBS and PBS/BSG were characterized by various physical and morphological tests during processing cycles. The results indicated that PBS is more stable than PBS/BSG and that both are recyclabl although with different numbers of possible cycles. More processing steps are needed to ensure optimal dispersion of BSG in the bio-polymer matrix.