Abstract
A systematic study on the degradation and mechanism of composite materials based on polybutylenes succinate/ polycaprolactone (PBS/PCL) was conducted by putting composites of different ratios into the local soil culture solution and cured compost culture solution to observe the microbial reaction. The surface morphologies, crystallinities, and structures of the composites before and after degradation were characterized by FTIR, XRD, and SEM. The results revealed that the original functional groups of the composites were retained perfectly after the mixing and fusing of PBS and PCL, and hydrogen bonds were formed between these two phases. The composite based on PBS and PCL degraded well in the compost culture solution. The weight of this composite was reduced by 32.67% after 60 d. Degradation of the composite in the soil culture solution was indicated by a weight loss up to 8.76%. PCL degraded much faster than PBS did, while the PBS/PCL composite degraded even faster. Crystallinity was improved after degradation, and the non-crystalline area degraded first. The viscosity analysis showed that the degradation of the composite was achieved by the simultaneous processes of breaking big molecules into small molecules and by the degradation of small molecules.
Biodegradable and environmental friendly PBS that belongs to aliphatic series polyester is one of the most promising environmental-friendly and biodegradable polymer materials; PCL is a kind of thermal plastic crystalline polyester with good bio-degradability, drug permeability, and biocompatibility. Meanwhile, the raw materials for PCL preparation are cost-effective and accessible. Due to the wide application of bio-degradable materials, the relationship between the degrading rate and the molecule design of bio-degradable material is becoming a key research topic in the area of biodegradable materials1–10. Zhang et al. studied the relationship between the chemical structure of PBS and its degradable structure11–16; the influences of microorganism quantity, humidity, temperature, metal ions, and pH on the degradable property were also studied17–21. In addition to the factors mentioned above22–26, adding other materials also greatly influences degradation performance. In practical applications, the mechanical properties of biodegradable materials are not as good as conventional plastics; the uncontrollable degradation rate of the biodegradable materials is another issue that prevents their wider promotion.
In this project, PBS/PCL composites of different ratios were prepared. Good mechanical properties and good biodegradability were expected for these composites. A systematic study on the degradation of these composites is presented, which provides good reference for the controllable application of biodegradable plastics. Furthermore, the degradation mechanism of the composites is rationally inferred, which is well supported by reported data. This study facilitates further research on the controlling of degrading rate of PBS/PCL.